CN113147258A

CN113147258A - Hub inner ring and manufacturing method thereof, hub assembly and manufacturing method thereof

Info

Publication number: CN113147258A
Application number: CN202110384086.2A
Authority: CN
Inventors: 李先云
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2021-07-23
Anticipated expiration: 2041-04-09
Also published as: CN113147258B

Abstract

The invention provides a hub inner ring and a manufacturing method thereof, and a hub assembly and a manufacturing method thereof. The inner ring of the hub is a hollow cylinder and is provided with a plurality of convex structures. The convex structure protrudes outwards from the outer peripheral surface of the hollow cylinder of the inner ring of the hub and is obtained in the casting process. The joint surface of the hub and the inner ring of the hub is provided with a plurality of concave structures which are shaped outside the corresponding convex structures in a shape matching manner through the cast-in process. The hub is made of light alloy materials, and the inner ring of the hub is made of iron-carbon alloy, so that the weight of the hub can be reduced while the structural strength requirement of the hub is met.

Description

Hub inner ring and manufacturing method thereof, hub assembly and manufacturing method thereof

Technical Field

The invention relates to the field of vehicle manufacturing, in particular to a hub inner ring and a manufacturing method thereof, and a hub assembly and a manufacturing method thereof.

Background

Various vehicles are widely used in the transportation of people and goods, and the wheel hub is used as an important link for transferring force between a vehicle body and the ground, so that the bearing capacity of the whole vehicle is influenced by the structural strength of the wheel hub, and the oil consumption of the vehicle is influenced by the weight of the wheel hub. Considering the fuel economy index of the vehicle, the smaller the weight of the wheel hub is, the more advantageous the wheel hub is on the premise of meeting the requirement of the bearing capacity of the whole vehicle. Therefore, weight reduction is increasingly becoming one of the main indicators in the hub production process.

In order to meet the strength requirements of the vehicle for the wheel hub, the conventional wheel hub is mostly made of cast iron, and the wall surface is usually thick. In order to reduce the weight of the hub, some lower density lightweight metal materials are used to manufacture the hub, such as aluminum alloys. However, the light alloy has the disadvantages of low yield strength, large thermal expansion coefficient, remarkable heat fading and the like, and cannot reliably meet the structural strength requirement of the hub.

In order to solve the problems of heavy weight of iron alloy materials and insufficient strength of aluminum alloy materials, the related hubs are manufactured by composite materials made of steel and aluminum alloy. Take the chinese utility model patent of publication number CN207128439U as an example, this utility model discloses a lightweight steel aluminium combined material wheel hub for commercial car, wheel hub body wherein adopts aluminum alloy material to make, and the bearing hole cover of inside and outside then adopts steel material to make to compromise the technical effect that aluminum alloy material light in weight and steel material intensity are big.

However, the hub made of two alloy materials is easy to have the technical problems of insufficient bonding strength and insufficient close fitting among different materials. In view of the above, the utility model discloses a joint surface structure that the wheel hub body made of aluminum alloy and steel bearing hole cover improves bonding strength for latticed or echelonment nonplanar, but latticed or echelonment nonplanar promotes the bonding strength between the different material joint surfaces limitedly, and under the condition that wheel hub bears great work load, appears the mutual dislocation between the different material joint surfaces because of bonding strength is not enough easily, produces adverse effect to wheel hub's security performance. The mutual dislocation between the joint surfaces of different materials can generate larger gaps, thereby causing low heat transfer efficiency, leading the working temperature of the bearing or the hub to exceed an allowable value and influencing the service life of the hub.

Disclosure of Invention

In view of the above, the invention provides a hub inner ring and a manufacturing method thereof, and a hub assembly and a manufacturing method thereof, which can significantly improve the bonding strength and the heat conductivity coefficient between the hub and the hub inner ring in the hub assembly on the premise of satisfying the structural strength of the hub and reducing the weight of the hub.

In one aspect of the invention, a hub inner ring is provided, the hub inner ring is a hollow cylinder, and the hub inner ring is provided with a plurality of convex structures, and the convex structures protrude outwards from the outer peripheral surface of the hollow cylinder of the hub inner ring.

Preferably, the projection structure comprises a mushroom-shaped projection, and the mushroom-shaped projection meets the following requirements:

making a longitudinal section perpendicular to the axial direction on the inner ring of the hub, wherein the longitudinal section passes through a convex structure to form a longitudinal section graph of the convex structure, in the longitudinal section graph, a connecting line between the lowest points of two side boundaries of the convex structure is used as a convex root datum line, the boundary distance between the two side boundaries of the longitudinal section graph is measured along the direction parallel to the convex root datum line, then at least one boundary line parallel to the convex root datum line is used for dividing the longitudinal section graph of the convex structure into at least two areas, and the distance between the boundary line and the convex root datum line is between 1/3 and 2/3 of the height of the convex structure;

wherein a maximum boundary distance of the longitudinal profile of at least one region farther from the projection root reference line is greater than a minimum boundary distance of the longitudinal profile of at least one region closer to the projection root reference line.

Preferably, in the plurality of projection structures, the ratio of the fungiform projections is 35-95%.

Preferably, the projection structure further comprises a table-shaped projection, and the table-shaped projection meets the following requirements:

making a longitudinal section perpendicular to the axial direction on an inner ring of the hub, wherein the longitudinal section passes through the convex structure to form a longitudinal section graph of the convex structure, in the longitudinal section graph, a connecting line between the lowest points of two side boundaries of the convex structure is used as a convex root datum line, and the boundary distance between the two side boundaries of the longitudinal section graph is measured along a direction parallel to the convex root datum line;

wherein a boundary distance of the longitudinal profile is constant or gradually decreased as a distance from the protrusion root reference line is gradually increased.

Preferably, in the plurality of projection structures, a ratio of the mesa-shaped projection is 5% to 65%.

Preferably, the average value of the top surface area of the convex structure is between 0.1 and 3mm²And the surface of the top surface area is perpendicular to the radial direction of the hub inner ring.

Preferably, the height of the raised structures has an average value of between 0.3 and 1.0 mm.

Preferably, the average value of the distribution density of the plurality of the convex structures relative to the hub inner ring is between 15 and 50/cm²。

In another aspect of the present invention, there is provided a method for manufacturing a hub inner ring according to any one of the foregoing embodiments, including the steps of:

smelting the ingredients with the set proportion into molten iron, and carrying out molten iron treatment on the molten iron;

preheating and rotating a hub inner ring casting mold, and uniformly coating the coating on the inner wall of the hub inner ring casting mold;

after the coating is dried, pouring molten iron treated by molten iron into the hub inner ring casting mold;

keeping the hub inner ring casting mold rotating; and

and demolding after the molten iron is solidified and molded, and removing the coating layer on the surface of the demolded casting to obtain the hub inner ring casting with the convex structure.

Preferably, the coating comprises:

4 to 7 mass percent of sodium bentonite;

15-25% by mass of diatomite;

0-5% of 350-mesh quartz sand by mass percentage;

0.0005 to 0.01 mass percent of alkyl sulfate; and

the balance being water.

Preferably, when the coating is coated, the rotating speed of the hub inner ring mold is controlled to be 700-1200r/min, and the temperature of the hub inner ring mold is controlled to be 200-300 ℃; and when molten iron is poured into the hub inner ring casting mold, controlling the rotating speed of the hub inner ring casting mold to be 1000-1600 r/min.

Preferably, the material of the hub inner ring comprises nodular cast iron, and the temperature of the molten iron during casting is 1380-1450 ℃.

In another aspect of the present invention, there is provided a hub assembly comprising the inner ring according to any one of the preceding embodiments, the hub assembly further comprising:

the hub is positioned on the periphery of the inner ring of the hub and is provided with a bearing hole; and

the hub bearing is positioned in the hub inner ring, and the outer ring of the hub bearing is fixedly arranged on the inner peripheral surface of the hollow cylinder of the hub inner ring;

the hub is formed on the outer peripheral surface of the hollow cylinder of the hub inner ring through an insert casting process, so that a plurality of concave structures matched with the plurality of convex structures are arranged on the joint surface of the hub and the hub inner ring.

Preferably, the material of the hub comprises a light alloy, and the material of the hub inner ring comprises an iron-carbon alloy.

In another aspect of the invention, there is provided a method of manufacturing a hub assembly according to any of the preceding embodiments, comprising the steps of:

a) manufacturing the hub: arranging the manufactured hub inner ring at the position of a central hole of a hub casting mold, injecting the light alloy smelted into a liquid state into a cavity of the hub casting mold, injecting the light alloy smelted into the liquid state into the cavity of the hub casting mold in an embedding casting mode, and mechanically processing the hub to a target size after the light alloy is cooled and shaped in the hub casting mold to obtain the hub embedded with the hub inner ring;

b) assembling a hub bearing and a hub inner ring: the hub bearing is mounted to the inner peripheral surface of the hollow cylinder of the hub inner ring.

Preferably, the casting mode of injecting the light alloy melted into the cavity of the hub casting mold is pressure insert casting, and the liquid light alloy in the cavity of the hub casting mold is kept at the temperature and pressure during the pressure insert casting process until the liquid light alloy is completely solidified.

Therefore, according to the embodiment of the invention, different parts in the hub assembly are made of different materials, so that the structural strength requirement of the hub can be met, the weight of the hub can be reduced, and the fuel economy of an automobile can be improved. And, through the mutual cooperation between protruding structure and the sunk structure, can improve bonding strength and coefficient of heat conductivity between wheel hub inner circle and the wheel hub to increase the factor of safety and the life-span of wheel hub in the use.

Drawings

FIG. 1 is a schematic structural view of a hub assembly of the present invention;

FIG. 2 is a schematic view of the outer peripheral surface of the hollow cylinder of the inner ring of the hub and the structure of the upper protrusions thereof according to the present invention;

FIG. 3 is a schematic structural view showing a longitudinal sectional view of a mesa-shaped protrusion formed on the outer peripheral surface of a hollow cylinder of the inner ring of the hub in the present invention;

FIG. 4 is a schematic metallographic structure of a longitudinal sectional view of a mesa-shaped protrusion on the outer circumferential surface of a hollow cylinder of the hub inner ring according to the present invention;

FIG. 5 is a schematic metallographic structure of another vertical sectional view of a mesa-shaped protrusion on the outer circumferential surface of a hollow cylinder of the hub inner ring according to the present invention;

FIG. 6 is a schematic longitudinal sectional view of the mushroom-shaped protrusions formed on the outer circumferential surface of the hollow cylinder of the inner ring of the hub according to the present invention;

FIG. 7 is a schematic metallographic structure of longitudinal sectional views of some mushroom-shaped protrusions formed on the outer circumferential surface of a hollow cylinder of the inner ring of the hub according to the present invention;

FIG. 8 is a metallographic structure diagram showing a longitudinal cross-sectional view of some of the protrusions formed on the outer circumferential surface of the hollow cylinder of the inner ring of the hub according to the present invention;

FIG. 9 is a schematic metallographic structure at a top view angle of a plurality of raised structures on the outer circumferential surface of a hollow cylinder of the inner ring of the hub according to the present invention;

FIG. 10 is a schematic view of the distribution of the test sampling area between the inner ring and the hub;

FIG. 11 is a schematic view of the thermal conductivity test of the test sampling area in the present invention;

FIG. 12 is a schematic view of the bonding strength test of the test sampling area of the present invention;

FIG. 13 is a schematic diagram showing the relationship between the bonding strength of the bump structures in the test sampling area and the height of the bump structures according to the present invention;

FIG. 14 is a graph illustrating the variation of the bonding strength of the bump structures and the height of the bump structures in the test sample area according to the present invention;

FIG. 15 is a schematic diagram illustrating a relationship between a thermal conductivity of a bump structure in a test sampling area and a height of the bump structure according to the present invention;

FIG. 16 is a schematic diagram illustrating the variation trend of the thermal conductivity of the bump structures and the height of the bump structures in the test sampling area according to the present invention;

FIG. 17 is a schematic diagram illustrating the relationship between the bonding strength of the bump structures in the test sampling area and the distribution density of the bump structures according to the present invention;

FIG. 18 is a graph showing the variation of the bonding strength of the bump structures and the distribution density of the bump structures in the test sample area according to the present invention;

FIG. 19 is a schematic diagram showing the relationship between the thermal conductivity of the bump structures in the test sampling area and the distribution density of the bump structures according to the present invention;

FIG. 20 is a schematic diagram illustrating the variation trend of the thermal conductivity of the bump structures and the distribution density of the bump structures in the test sampling area according to the present invention;

FIG. 21 is a schematic view showing the shape of a complete mushroom-shaped protrusion when a longitudinal cross section is taken for the protrusion structure according to the present invention;

FIG. 22 is a schematic view showing the shape of a mushroom-shaped projection with its pileus removed when the projection structure is taken in a longitudinal section according to the present invention;

FIG. 23 is a schematic view of the shape of a mesa-like protrusion when the protrusion structure is taken in a longitudinal section in accordance with the present invention.

Description of reference numerals:

1-hub 11-bearing hole 2-hub bearing

3-hub inner ring 31-first positioning step 32-second positioning step

4-convex structure 41-mushroom-shaped convex 42-platform-shaped convex

51-first top surface area 52-second top surface area 53-third top surface area

54-fourth Top surface area 55-fifth Top surface area 61-first test sampling region

62-second test sampling area 63-bonding strength test tool 64-tensile force direction

q 1-first region q 2-second region q 3-third region

A-first lowest point B-second lowest point C-boundary distance

D-maximum boundary distance D-minimum boundary distance

Detailed Description

Various exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is not intended to limit the invention, its application, or uses. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be noted that: unless specifically stated otherwise, the relative positions of components, steps, compositions of materials, numerical expressions, and numerical values set forth in these embodiments are to be construed as merely illustrative, and not a limitation.

In a first aspect of the invention:

as shown in fig. 1 to 8, a hub inner ring 3 is provided, the hub inner ring 3 is a hollow cylinder, the hub inner ring 3 has a plurality of protruding structures 4, and the protruding structures 4 protrude outwards from the outer peripheral surface of the hollow cylinder of the hub inner ring 3.

As shown in fig. 2, the plane indicated by reference numeral 3 illustrates the outer peripheral surface of the hub inner ring 3. On the outer peripheral face of wheel hub inner circle 3, distribute a plurality of protruding structures 4, and a plurality of protruding structures 4 have different form types. In this regard, fig. 2 illustrates collectively several different types of projection structures 4.

Those skilled in the art will understand that: the different types of projection structures 4 should be irregularly distributed on the outer circumferential surface of the hub inner ring 3, and the sequence in fig. 2 does not limit the actual distribution of the different types of projection structures 4 on the outer circumferential surface of the hub inner ring 3: the different types of projection structures 4 may coexist on the outer peripheral surface of the one hub inner ring 3, or may exist independently on the outer peripheral surface of the one hub inner ring 3. Also, as shown in fig. 1, the outer peripheral surface of the hub inner ring 3 is substantially a cylindrical surface, and the cross section thereof in fig. 2 is correspondingly a circle, however, for convenience of illustration and description of the plurality of convex structures 4 on the outer peripheral surface of the hub inner ring 3, the outer peripheral surface of the hub inner ring 3 is drawn in a straight line in fig. 2.

Because the hub 1 is combined on the outer peripheral surface of the hollow cylinder of the hub inner ring 3 through the insert casting process, the convex structures 4 can improve the heat conduction performance and the combination strength between the hub 1 and the hub inner ring 3. As will be described in detail below.

For the heat conduction performance, the contact area of the hub inner ring 3 and the hub 1 can be increased by the convex structures 4, so that the heat conduction performance between the hub inner ring 3 and the hub 1 made of the light alloy is enhanced, heat generated by the hub bearing 2 in the operation process is rapidly transmitted to the hub 1 made of the light alloy through the hub inner ring 3, the operation temperature of the hub bearing 2 is reduced, the thermal deformation of the hub bearing is reduced, and the friction coefficient of the hub bearing is reduced.

Aiming at the bonding strength, in the process of inlaying and casting the hub 1 on the hub inner ring 3, the plurality of convex structures 4 on the outer peripheral surface of the hollow cylinder of the hub inner ring 3 can be mutually occluded with the concave structures on the hub 1 to form a mortise and tenon structure, so that the hub 1 and the hub inner ring 3 are tightly combined together, the circumferential torque transmission capacity of the hub 1 and the hub inner ring 3 is improved, and the relative displacement of the hub 1 and the hub inner ring 3 in the process of repeated expansion and contraction due to different materials is reduced.

In order to facilitate structural description of the hub inner ring 3 and the convex structure 4, a cylindrical coordinate system is established by taking the central axis of the hollow cylinder of the hub inner ring 3 as an axis for discussion. Based on the cylindrical coordinate system, it should be noted that:

first, limited by the manufacturing method, the outer circumferential surface of the hollow cylinder of the hub inner ring 3 has a plurality of convex structures 4, and the convex structures 4 and the concave regions between adjacent convex structures 4 will make the actual outer circumferential surface of the hollow cylinder of the hub inner ring 3 uneven. Therefore, when the position and the form of the convex structure 4 are defined by the outer peripheral surface of the hollow cylinder of the hub inner ring 3, in order to make the definition more accurate, the outer peripheral surface of the hollow cylinder of the hub inner ring 3 is referred to as a reference surface at the time of roughness measurement, which is a cylindrical surface configured by taking the axial height of the lowest point of the periphery of the bottom of each convex structure as a statistical object and taking the arithmetic mean value as a radius. When the lowest point around the bottom of each protruding structure is taken, the pit formed by the casting defect should be excluded from the selection range of the lowest point.

Secondly, the outer peripheral surface of the hollow cylinder of the hub inner ring 3 is a cylindrical surface, and the section of the hollow cylinder vertical to the axial direction is correspondingly circular. However, in order to compare morphological differences between different convex structures, the outer peripheral surface of the hub inner ring 3 is drawn as a straight line in fig. 2, 3, and 6, and each of the circular contour lines having the outer peripheral surface of the hollow cylinder of the hub inner ring 3 as a reference surface is also drawn as a straight line. In this regard, it will be understood by those skilled in the art that the outer peripheral surface of the hollow cylinder of the hub inner ring, here in a straight line, should in practice be a cylindrical surface and the individual contour lines in a straight line should in practice be circular contour lines.

Thirdly, the direction of the outward protrusion of the convex structure 4 is from the outer circumferential surface of the hollow cylinder of the hub inner ring 3 to the top end or top surface of the convex structure 4. Normally, the protruding direction of the protruding structure 4 is consistent with the radial direction of the hub inner ring, however, in consideration of the error that may occur in the manufacturing process, an included angle between the protruding direction of the protruding structure 4 and the radial direction of the hub inner ring in the range of less than 30 ° should also be considered as allowable.

Kind of the protruding structure

As shown in fig. 3-5, in a preferred embodiment, the bump structure 4 includes a mesa-shaped bump 42, and the mesa-shaped bump 42 satisfies the following requirements:

making a longitudinal section perpendicular to the axial direction of the hub inner ring 3, wherein the longitudinal section passes through the bulge structure to form a longitudinal section graph of the bulge structure, in the longitudinal section graph, a connecting line between the lowest points of the boundaries at the two sides of the bulge structure is used as a bulge root datum line, and the boundary distance between the boundaries at the two sides of the longitudinal section graph is measured along the direction parallel to the bulge root datum line;

wherein the boundary distance C of the longitudinal profile is constant or gradually decreased as the distance from the projection root reference line is gradually increased.

The following is illustrated by way of example in fig. 3-5: fig. 3-5 are longitudinal sections of the hub inner ring 3 perpendicular to the axial direction, which form longitudinal sectional patterns of the plurality of convex structures 4 through the plurality of convex structures 4. Fig. 4 and 5 are metallographic structure diagrams of a longitudinal section of a convex structure, and the edges of the longitudinal section in the metallographic structure diagrams are drawn to form the structural diagram of the longitudinal section of the convex structure shown in fig. 3. On the basis, if a projection structure is determined to be a mesa projection, it is determined whether the boundary distance C of the longitudinal-cut graph is not increased further away from the base line of the projection root.

Specifically, in fig. 3, a connection line AB is first formed between the lowest points (the first lowest point a and the second lowest point B) of the two side boundaries of the protruding structure, and the connection line AB is a protruding root reference line of the protruding structure. And secondly, measuring a plurality of boundary distances C when the height is higher than the connecting line AB. Finally, whether the length of the boundary distances C is not increased any more as the boundary distances C are farther away from the root datum line of each bump is judged for each bump structure. The longitudinal sectional views of the two projection structures shown in fig. 3 both satisfy the structural feature requirements of the mesa-like projection and therefore belong to the mesa-like projection 42.

In order to facilitate measurement of each protrusion structure, in fig. 3, a base line (connection line AB) of a circular arc-shaped protrusion root and a boundary distance C are both drawn as straight lines. However, it will be understood by those skilled in the art that the outer peripheral surface of the hollow cylindrical body of the hub inner ring has a circular cross-sectional shape perpendicular to the axial direction, and the projection root reference line of each projection structure is a small segment of the circular cross-sectional shape, so that the projection root reference line in fig. 3 should have a circular arc shape. Similarly, the boundary distance C of the vertical section pattern should also be the arc length at which a plurality of circular contours based on the circular sectional shape fall within the vertical section pattern.

The combination of the mesa-shaped protrusions 42 and the corresponding concave structures can increase the heat transfer area between the hub and the inner ring of the hub and the capability of transferring torque along the circumferential direction. Moreover, the boundary distance of the longitudinal section of the mesa-shaped protrusion 42 is gradually reduced along the radial direction of the hub inner ring 3, so that metal can be fully filled around the mesa-shaped protrusion 42 in the hub casting process.

In another preferred embodiment, as shown in fig. 6 and 7, the raised structure comprises a mushroom-shaped projection, which satisfies the following requirements:

and making a longitudinal section perpendicular to the axial direction of the hub inner ring 3, wherein the longitudinal section passes through the convex structure to form a longitudinal section pattern of the convex structure. In the longitudinal section graph, a connecting line between the lowest points of the boundaries at the two sides of the convex structure is used as a convex root datum line, the boundary distance between the boundaries at the two sides of the longitudinal section graph is measured along the direction parallel to the convex root datum line, then the longitudinal section graph of the convex structure 4 is divided into at least two areas by at least one dividing line parallel to the convex root datum line, and the distance between the dividing line and the convex root datum line is between 1/3 and 2/3 of the height of the convex structure;

wherein the maximum boundary distance D of the longitudinal profile in at least one region farther from the bump root reference line is greater than the minimum boundary distance D of the longitudinal profile in at least one region closer to the bump root reference line.

The following is illustrated by taking fig. 6 and 7 as an example: fig. 6 and 7 are longitudinal sections of the hub inner ring 3 perpendicular to the axial direction, and the longitudinal sections form longitudinal sectional patterns of the plurality of convex structures 4 through the plurality of convex structures 4. Fig. 7 is a metallographic structure diagram of a vertical section of the convex structure, and the structure diagram of the vertical section of the convex structure shown in fig. 6 is formed by drawing the edge of the vertical section in the metallographic structure diagram. On the basis, to judge whether a specific protrusion structure is a mushroom-shaped protrusion, it is necessary to compare whether the maximum boundary distance D of the longitudinal-cut figure in the region farther from the base line of the protrusion is greater than the minimum boundary distance D of the longitudinal-cut figure in the region closer to the base line of the protrusion.

Specifically, in fig. 6, a connection line between the lowest points of the boundaries on both sides of the projection structure is first set as a projection root reference line (connection line AB). Next, the vertical sectional pattern of the projection structure 4 was divided into 3 regions by 2 boundary lines parallel to the projection root reference line and having a distance from the projection root reference line between 1/3-2/3 of the height of the projection structure, and these 3 regions were named a first region q1, a second region q2 and a third region q3 in this order from the near to the far distance from the projection root reference line. On the basis of this, the maximum boundary distance D and the minimum boundary distance D are measured for the longitudinal profile of the relief structure in each region. Finally, whether the maximum boundary distance D of one area is larger than the minimum boundary distance D of the other area exists in each protruding structure is judged, and the area where the maximum boundary distance D is located is farther away from the protruding root datum line (connecting line AB) than the area where the minimum boundary distance D is located.

For the sectional pattern of the first bulge structure from the left, the maximum boundary distance D of the third area is greater than the minimum boundary distance D of the second area, and the third area is farther away from the bulge root datum line than the second area, and the size relationship meets the requirement of the fungiform bulge, so that the bulge structure is considered as the fungiform bulge. The second to sixth convex structures from the left can be judged to be mushroom-shaped convex structures in the same way as the second convex structure from the left.

Similarly to fig. 3, the outer peripheral surface of the hollow cylinder of the hub inner ring is also circular in cross-sectional shape in fig. 6, and the maximum boundary distance D and the minimum boundary distance D of each of the projection structures are also obtained by the circular contour lines falling within the range of the longitudinal sectional pattern. In fig. 6, the projection root reference line (connection line AB), the maximum boundary distance D, and the minimum boundary distance D are also plotted as straight lines to facilitate measurement of the respective projection structures.

The mushroom-shaped projection has a feature that "the maximum boundary distance D of the longitudinal-section pattern of at least one region farther from the projection root reference line is greater than the minimum boundary distance D of the longitudinal-section pattern of at least one region closer to the projection root reference line", so that the mushroom-shaped projection forms a structural feature that the position where the boundary distance is greater is farther from the projection root reference line and the position where the boundary distance is smaller is closer to the projection root reference line between at least one combination of two different regions (for example, a combination of a third region and a second region), and thereby an improvement in structural strength and thermal conductivity is obtained.

Specifically, considering that the angular difference between the height direction of the projection structure and the radial direction of the hub inner ring has a reasonable range, the distance from the projection root reference line is equal to the distance in the radial direction, and therefore, for a mushroom-shaped projection having a structural feature that a position with a large boundary distance is located outward and a position with a small boundary distance is located inward, the hub forms a recessed structure corresponding to the structural feature of the mushroom-shaped projection on the joint surface with the hub inner ring: the recessed structures corresponding to the locations of the mushroom-shaped protrusions having smaller boundary distances will form hole regions having the same smaller boundary distances, while the recessed structures corresponding to the locations of the mushroom-shaped protrusions having larger boundary distances will form hole regions having the same larger boundary distances. Therefore, if the joint surface of the hub and the hub inner ring bears radial load, the position with larger boundary distance in the mushroom-shaped bulge is mutually hooked with the hole area with smaller boundary distance in the concave structure, and the hub inner ring are prevented from being separated from each other in the radial direction, so that the bonding strength between the hub inner ring and the hub is improved.

Taking the mushroom-shaped protrusions 41 shown in fig. 6 as an example, the cross-sectional pattern of the mushroom-shaped protrusions forms a first change of the boundary distance between the first region and the second region, and forms a second change of the boundary distance between the second region and the third region, and the two changes of the boundary distances make the mushroom-shaped protrusions 41 have a larger specific surface area (surface area/volume) within the same height range, so that the heat conduction performance between the hub inner ring 3 and the hub 1 of light alloy can be improved.

The occupation ratio of different types of convex structures.

In a preferred embodiment, the ratio of the mushroom-shaped protrusions 41 in the plurality of protrusion structures 4 is 35% to 95%.

The ratio of the mushroom-shaped protrusions 41 is higher than 35%, and the combination strength and the heat conductivity coefficient between the hub inner ring and the hub can be improved by utilizing the mushroom-shaped protrusions. Specifically, the method comprises the following steps: the mushroom-shaped protrusions can improve the size of mutual occlusion in the tenon-and-mortise fit relation between the protrusion structures and the depression structures, and especially can form radial occlusion between the protrusion structures and the depression structures, so that the combination strength between the hub and the inner ring of the hub is improved. In addition, on the longitudinal section graph of the mushroom-shaped bulges perpendicular to the axial direction, the boundary distance of the mushroom-shaped bulges is changed along the radial direction of the hub inner ring 3, so that the mushroom-shaped bulges 41 have larger specific surface area in the same height range, the heat transfer area of the mushroom-shaped bulges and the corresponding concave structures is increased, and the heat conductivity coefficient between the hub and the hub inner ring is improved.

The proportion of the mushroom-shaped protrusions 41 is lower than 95%, so that the metal fluidity of the hub in the casting process can be guaranteed, and the filling of the concave structure is fuller. Specifically, the method comprises the following steps: in the process of casting-in the hub, the liquid light alloy for manufacturing the hub needs to flow through the region, far away from the datum line of the root of the protrusion, of the protrusion structure first, and then can be filled into the region, near the datum line of the root of the protrusion, of the protrusion structure. The region with larger boundary distance in the longitudinal section pattern of the mushroom-shaped protrusion 41 is far away from the base line of the root of the protrusion, so that the liquid light alloy is difficult to bypass the region with larger boundary distance in the longitudinal section pattern of the mushroom-shaped protrusion and fill the region with smaller boundary distance to the periphery of the region with smaller boundary distance in the imbedding process, the shape of the concave structure is not full, and micro pores are easily generated between the protrusion structure and the hub. The small gaps influence the proportion of the effective heat transfer area between the convex structures and the concave structures to the total contact area, and further influence the heat transfer performance between the hub and the hub inner ring.

In another preferred embodiment, the proportion of the mesa-shaped projections 42 in the plurality of projection structures 4 is 5% to 65%.

The proportion of the table-shaped bulges 42 is limited to be not more than 65%, and the plurality of bulge structures 4 can be ensured to comprise the fungiform bulges with sufficient proportion, so that the heat conductivity coefficient and the bonding strength between the hub and the hub inner ring are ensured by the fungiform bulges with more heat transfer area, larger tenon-mortise matched occlusion size and radial occlusion capacity. And the ratio of the limiting platform-shaped bulge 42 is not lower than 5%, the enough ratio of the platform-shaped bulge 42 can ensure the metal fluidity of the hub in the casting process, particularly the pressure insert casting or gravity insert casting process, so that the filling of the concave structure is fuller.

In another preferred embodiment, in the plurality of projection structures 4, the proportion of the mushroom-shaped projections 41 is 35% to 95%, and the proportion of the mesa-shaped projections 42 is 5% to 65%.

Therefore, by simultaneously controlling the occupation ratio of the fungiform protrusions 41 and the occupation ratio of the platform-shaped protrusions 42, the metal fluidity is better in the casting process and the filling of the concave structure is fuller while the bonding strength and the heat conduction performance between the hub inner ring 3 and the hub 1 are ensured to meet the requirements.

The statistical method of the types of the convex structures has the following influence on the proportion of the types:

when a vertical section of a convex structure is taken as an object in the statistical convex structure category, it is noted that: for the mesa-shaped protrusion, the position of the longitudinal section hardly affects the shape of the longitudinal section of the mesa-shaped protrusion, that is, at most of the positions of the longitudinal section, the longitudinal section of the mesa-shaped protrusion has a trapezoidal shape with a lower base close to the base line of the protrusion root and an upper base far away from the base line of the protrusion root.

However, as shown in fig. 21, the longitudinal section of the mushroom-shaped protrusion can be made to have a complete mushroom-shaped protrusion shape as shown in fig. 21 only when the longitudinal section is distributed between L2-L3, a mushroom-shaped protrusion shape with the pileus removed as shown in fig. 22 when the longitudinal section is distributed between L1-L2 or L3-L4, and a truncated protrusion shape as shown in fig. 23 when the longitudinal section is distributed outside L1 or outside L4.

In which the sectional shape shown in fig. 21 and 22 can be obtained only when the projection structure is a mushroom-shaped projection, and therefore statistical deviation does not occur in counting the projection structure into the mushroom-shaped projection, but it is difficult to distinguish whether the shape of the mesa-shaped projection shown in fig. 23 is obtained by cutting the mushroom-shaped projection or the mesa-shaped projection.

As shown in fig. 8, the sectional pattern of the second complete protrusion structure from the left is low in height, and it is difficult to determine whether the cross-sectional pattern is obtained by cutting the mushroom-shaped protrusion or the mesa-shaped protrusion. In contrast, in the process of statistics, the convex structure with the height lower than 0.3mm is not considered, so that the statistical deviation generated by 'misjudging the shape of part of the truncated convex obtained by cutting the fungiform convex as the shape of the truncated convex' is eliminated.

As can be seen from table five, when the number of the projection structures in one detection region is small, the ratio deviation of the mushroom-shaped projections or the mesa-shaped projections is large, and when the statistical results of the plurality of detection regions are summarized, the ratio of each of the mushroom-shaped projections and the mesa-shaped projections is stably distributed at about 60% and about 40%, respectively.

Considering the deviation of the statistical method and the deviation of the sample amount of the bulge structure in the detection area, the ratio of the mushroom-shaped bulge in the present invention is preferably 35-95%, and the ratio of the mesa-shaped bulge is preferably 5-65%.

Top surface area of bump structure

In a good priorityIn a preferred embodiment, the average of the top surface areas of the raised structures 4 is between 0.1 and 3mm²The surface of the top surface area is perpendicular to the radial direction of the hub inner ring 3.

The average value of the top surface area of the convex structures 4 is between 0.1 and 3mm²On the basis of ensuring the complete forming of the convex structure, the technical effects of enhancing the heat conductivity coefficient and increasing the bonding strength brought by the convex structure can be realized as much as possible.

Specifically, the larger the area of the top surface of the protruding structure is, the larger the heat transfer area between the hub inner ring and the hub, which is increased by the protruding structure and the recessed structure, is, and the larger the engagement size of the mortise-tenon joint between the protruding structure and the corresponding recessed structure is. However, the forming difficulty of the convex structure is increased by the excessively large area of the top surface, and in the process of insert casting of the hub, the liquid light alloy is difficult to bypass the top of the convex structure and fill between the top of the convex structure and the outer peripheral surface of the hollow cylinder of the hub inner ring, so that micro pores are easily generated between the convex structure and the hub, and further, the gap between the convex structure and the concave structure is increased in the repeated expansion and contraction process, and the heat transfer performance and the bonding strength between the hub and the hub inner ring are affected.

Example of calculation of the area of the top surface of the protruding structure:

taking the outer peripheral surface of the hollow cylinder of the hub inner ring as a reference surface, cutting a transverse section of the convex structure at a set radial height along a direction vertical to the radial direction of the hub inner ring, and calculating the area of the transverse section, namely the area of the top surface of the convex structure.

Considering that there is a certain difference in the height of each of the convex structures, the radial height when the lateral section is taken is set as: and calculating an arithmetic mean value by taking the radial heights of the top highest points of all the convex structures in the sampling area as a statistical object, and subtracting 0.1mm from the calculated arithmetic mean value so as to intercept as many convex structures as possible by the transverse section.

For example: one area of each of 4 equal areas 10mm away from the upper end surface and the lower end surface of the inner ring of the hub along the circumferential direction is 100mm²Area (10mm square) as a samplingA sample area. In each sampling area, the transverse section of the convex structure is cut by taking the outer peripheral surface of the hollow cylinder of the hub inner ring as a reference and taking the set radial height. And (4) counting the areas of the transverse sections of all the intercepted convex structures, and averaging to obtain the area of the top surface of the convex structure.

Of course, considering the number of the convex structures on the outer peripheral surface of the hollow cylinder of the hub inner ring is large, it is preferable to select one convex structure in the lateral cross section at each of the four corners (corresponding to the first top area 51, the second top area 52, the fourth top area 54, and the fifth top area 55 shown in fig. 9) and the center (corresponding to the third top area 53) of the sampling region by the five-point method. The average value of the areas of the transverse cross sections of all five convex structures is the average value of the areas of the top surfaces of the convex structures in the sampling area.

Height of the bump structure

In a preferred embodiment, the height of the raised structures 4 has an average value of between 0.3 and 1.0 mm.

The height of the raised structure 4 affects the thermal conductivity and bonding strength of the hub and the hub inner ring.

Specifically, when the height of the protruding structure is less than 0.3mm, the protruding structure is often in a bulge shape, and it is difficult to form a mushroom-shaped protrusion or a mesa-shaped protrusion having a complete structural feature in the height direction, resulting in a low bonding strength between the protruding structure and the recessed structure. And the too low protruding structure is also very limited in the increase of the heat conduction area, so that the heat conduction coefficient of the hub and the hub inner ring is not obviously increased.

When the height of the convex structure is higher than 1.0mm, the high height of the convex structure can increase the insert casting forming difficulty of the convex structure and the concave structure matched with the convex structure, the shape filling is not full, the gap between the hub and the hub inner ring is easily increased in the process of repeated thermal barrier cold contraction, and the heat conductivity coefficient from the hub inner ring to the hub is reduced. In addition, the rigidity of the overhigh convex structure is poor, and the overhigh convex structure is easy to deform or even break when being subjected to radial load and circumferential load, so that the bonding strength between the hub and the hub inner ring is influenced.

Selecting the average value of the heights of the convex structures:

with reference to table one, fig. 13 and fig. 14, as the average height of the protrusion structures increases, the bonding strength between the hub and the inner ring of the hub tends to increase first and then decrease. Wherein the bump structure has a maximum bonding strength in the range of 0.69mm to 0.72mm in height, a high bonding strength in the range of 0.51mm to 0.95mm, substantially greater than 17MPa, a low bonding strength in the range of 0.4mm or less, and a bonding strength of less than 10 MPa.

With reference to table two, fig. 15 and fig. 16, as the average height of the protrusion structures increases, the heat conductivity from the inner ring of the hub to the hub also tends to increase first and then decrease. Wherein the maximum value of the thermal conductivity coefficient is obtained when the height of the convex structure is about 0.72mm, the thermal conductivity coefficient in the interval of 0.22mm-0.9mm is higher and is basically larger than 40W/m.k, and the thermal conductivity coefficient is basically not changed along with the increase of the height of the convex structure in the interval of more than 0.9 mm.

Considering the effect of the height of the protruding structure on the bonding strength and the thermal conductivity, the height of the protruding structure is preferably greater than 0.4mm and less than 0.9mm, so as to ensure sufficient bonding strength and efficient thermal conductivity between the hub and the hub inner ring. Considering again the errors during the experiment and the influence of the extreme values during the calculation of the mean value on the mean result, the mean value of the height of the relief structures 4 is preferably between 0.3 and 1.0 mm.

Height measurement example of bump structure:

one area of each of 4 equal areas 10mm away from the upper end surface and the lower end surface of the inner ring of the hub along the circumferential direction is 100mm²The area (10mm by 10mm square) served as the sampling area. And scanning the sampling area by adopting industrial CT to obtain a three-dimensional image containing the convex structures in the sampling area, and calculating the radial distance between the top or top surface of each convex structure and the reference surface by taking the outer peripheral surface of the hollow cylinder of the inner ring of the hub as the reference surface, namely the height of each convex structure.

Of course, the height measurement of the convex structures may also be performed by using a five-point method as shown in fig. 9, and one convex structure is selected from each of the four corners and the center of the sampling region for the height measurement.

When the height of the bump structure is measured by taking fig. 7 and 8 as an example, a connection line may be made between the left lowest point of the bump structure located at the leftmost side of the vertical section and the right lowest point of the bump structure located at the rightmost side of the vertical section, and then the vertical distance between the top point (or top surface) of the bump structure and the connection line is measured, which is the height of the bump structure.

Because the protruding structure is an as-cast structure, the size deviation of the protruding structure is large, and the height detection precision of the protruding structure is generally controlled to be 0.1 mm.

Distribution density of bump structure

In a preferred embodiment, the average value of the distribution density of the plurality of convex structures 4 relative to the hub inner ring 3 is between 15 and 50/cm²。

The distribution density of the convex structures 4 can also influence the heat conductivity coefficient and the bonding strength of the hub and the inner ring of the hub at the same time:

when the average value of the distribution density of the convex structures 4 is less than 15/cm²When the wheel hub is used, the raised structures in a unit area are distributed sparsely, so that the heat conduction area increased by the raised structures and the recessed structures and the mortise-tenon matched occlusion area are limited, and the heat conduction coefficient and the bonding strength of the wheel hub and the wheel hub inner ring are not obviously increased.

When the average value of the distribution density of the convex structures 4 is more than 50/cm²In the meantime, the protruding structures distributed too densely holdThe forming difficulty of the convex structure and the concave structure is increased easily, so that the convex structure and the concave structure generate gaps in the repeated thermal barrier cold contraction process due to insufficient full shapes, and the bonding strength and the heat conductivity coefficient of the hub and the inner ring of the hub are influenced.

Selecting the average value of the distribution density of the convex structures:

with reference to table three, fig. 17 and fig. 18, as the average value of the distribution density of the convex structures increases, the bonding strength between the hub inner ring and the hub tends to increase first and then decrease. Wherein the distribution density of the convex structures is 30/cm²The maximum value of the bonding strength was obtained in a region near the center of the specimen at 8 pieces/cm²-40/cm²Has a high bonding strength of substantially more than 15MPa and in the range of 48/cm²The bonding strength in the above interval is low and is substantially less than 1 MPa.

With reference to table four, fig. 19 and fig. 20, as the average value of the distribution density of the convex structures increases, the heat conductivity coefficient from the hub inner ring to the hub tends to increase first and then decrease. Wherein the distribution density of the convex structures is 32/cm²The maximum value of the thermal conductivity coefficient is obtained in the adjacent interval and is 22/cm²-50 mm²The thermal conductivity in the above interval is high, basically more than 35W/m.k, and 16/cm²The thermal conductivity is low and is substantially less than 25W/m.k in the following distribution density.

Considering the influence of the distribution density on the bonding strength and the thermal conductivity, the distribution density is preferably more than 16/cm²And at the same timeLess than 48 pieces/cm²To ensure sufficient bonding strength and thermal conductivity. Considering the error in the experimental process and the influence of the extreme value on the average result in the average value calculation process, the average distribution density of the convex structures is between 15 and 50/cm²。

Measurement of distribution density of the bump structure:

one area of each of 4 equal areas 10mm away from the upper end surface and the lower end surface of the inner ring of the hub along the circumferential direction is 100mm²The area (10mm by 10mm square) served as the sampling area. Counting the protruding structures with complete structures in the sampling area, counting the protruding structures on the upper boundary (or the lower boundary) and the right boundary (or the left boundary) of the sampling area, adding the results of the two counting to obtain the total number of the protruding structures in the sampling area, and dividing the total number by the area of the sampling area to obtain the distribution density of the protruding structures.

Examples of measurements of bond strength and thermal conductivity

Regarding the measurement of thermal conductivity:

as shown in fig. 10, the test sample block is cut along the radial direction on the joint surface of the hub and the hub inner ring, and the total thickness of the test sample block and the thickness occupied by the hub inner ring are limited in the cutting process: when the total thickness of the experimental sample block is a +/-0.05 mm, the thickness occupied by the hub inner ring is required to be 1/4 a +/-0.05 mm.

In the sampling process, 4-6 angles are uniformly taken along the circumferential direction to cut the experimental sample blocks, and under each circumferential angle, one experimental sample block is respectively cut at the position where the bearing is arranged on the inner ring of the hub along the axial direction, namely a first test sampling area 61 and a second test sampling area 62 shown in fig. 10.

In view of the small size, especially the thin thickness, of the test piece, the thermal conductivity of the test piece is preferably measured by a laser flash method after the test piece is cut out, as shown in fig. 11: under the condition of constant temperature, a laser lamp or a flash xenon lamp instantly emits light pulses from one side of an inner ring of a hub cut from an experimental sample block, the light pulses are uniformly irradiated on the surface of the one side of the inner ring of the hub cut from the experimental sample block, so that the temperature of the surface layer of the experimental sample block is instantly increased after the surface layer absorbs light energy, the surface layer is used as a hot end to transmit the energy to the surface of the one side of the hub cut from the experimental sample block in a one-dimensional heat conduction mode, the temperature rise process of the one side of the hub cut from the experimental sample block is measured, and the heat conductivity coefficient of the experimental sample block is calculated according to a relation curve of the temperature rise corresponding to time.

The heat conductivity coefficient represents the heat transfer speed of the experimental sample block from the inner ring of the hub to the hub, the higher the heat conductivity coefficient is, the better the heat conduction effect from the inner ring of the hub to the hub is, the faster the heat can be transmitted, and the running temperature of the bearing is reduced.

For the measurement of the bond strength:

the experimental sample block is cut by the method for measuring the same heat-conducting property, but the cutting process has no special size requirement on the thickness of the experimental sample block, and only two parts of the experimental sample block cut from the inner ring of the hub and the hub are required to be respectively fixed and clamped.

After the experiment sample block is cut out, as shown in fig. 12, two parts cut from the hub inner ring and the hub are respectively clamped on corresponding bonding strength testing tools 63, a tensile force is applied to the bonding strength testing tools through a material testing machine, and then the tensile force is gradually loaded along with the tensile force, so that the bonding strength of the hub inner ring and the hub is obtained by dividing the tensile force generated when the bonding surface between the hub inner ring and the hub of the experiment sample block is separated by the area of the bonding surface in the experiment sample block.

In order to avoid the influence of random errors in a single number of experiments on the accuracy of the measurement result, the average value of the data of the experiments is obtained in the process of obtaining the measurement result of the heat-conducting property and the bonding strength. And. The maximum and minimum values for each experiment were also recorded to discuss the effect of range on the mean calculation.

The measurement of the thermal conductivity with an average height of the projections of 0.22mm is illustrated as an example: the heat conductivity test was conducted on five sample blocks having an average height of 0.22mm in total, and the test results (W/m.k) were 33.49, 35.46, 36.47, 37.53 and 39.86, respectively, and the maximum value, the minimum value and the average value of these data were 39.86, 33.49 and 36.56, respectively, and they were included in the statistical tables.

Considering that a plurality of convex structures are usually included on a joint surface between two parts of an experimental sample block cut from a hub and an inner ring cut from the hub, in the experiment of the bonding strength and the heat conductivity coefficient, products obtained under different production conditions need to be selected for the experiment, for example, 10 experimental sample blocks with the average value of the heights of the convex structures being 0.22mm have the distribution density (one/cm)²) Respectively as follows: three of 38, one of 39, two of 40, two of 41, one of 42, one of 44, thus at 2/cm²For spacing, the density of 38, 40, 42 and 44 pieces/cm are selected respectively²The sample block is subjected to heat conductivity coefficient and bonding strength experiments, so that the distribution density of the convex structures is used as the selection point of experimental data of independent variables, and the points are more uniform.

In a second aspect of the invention:

the invention also provides a manufacturing method of the hub inner ring, which comprises the following steps: smelting the ingredients with the set proportion into molten iron, and carrying out molten iron treatment on the molten iron; preheating and rotating the hub inner ring casting mold, and uniformly coating the prepared coating on the inner wall of the hub inner ring casting mold; after the coating is dried, pouring molten iron treated by molten iron in a hub inner ring casting mold; keeping the hub inner ring casting mold rotating; and demolding after the molten iron is solidified and molded, and removing the coating layer on the surface of the demolded casting to obtain the hub inner ring casting with the convex structure.

In a preferred embodiment, the coating comprises: 4 to 7 mass percent of sodium bentonite; 15-25% by mass of diatomite; 0-5% of 350-mesh quartz sand by mass percentage; 0.0005 to 0.01 mass percent of alkyl sulfate; and the balance being water.

The formation process of the convex structure on the outer peripheral surface of the hollow cylinder of the inner ring of the hub is described as follows: the water-based coating added with the surfactant is coated on the inner surface of a hub inner ring casting mold which is heated and kept rotating, so that a casting coating layer is formed, water in the casting coating layer is vaporized under the preheating effect to generate bubbles, the surfactant in the casting coating layer is applied to each bubble, the surface tension of the bubble is increased, adjacent small bubbles are gradually fused, the volume is increased to form large bubbles, and simultaneously the uncured casting coating layer extrudes the bubbles under the centrifugal force effect.

Because the distribution state of the diatomite and the quartz sand in the coating is difficult to achieve absolute uniformity, the pressure born by the periphery of each large bubble is different, and various shapes of the large bubbles are generated, which correspond to different shapes of thicker and larger pileus parts in the fungiform protrusions. As the coating partially cures, the pressure within the large bubble continues to increase, and the bubble collapses as the internal pressure of the large bubble becomes greater than the centrifugal force of the coating on top of it. The broken channel forms a shape corresponding to the finer stipe in the mushroom-shaped bulge. And the inner surface of the casting coating layer is flushed to the periphery by the impact force generated when the bubbles are broken, so that a mycorrhiza part thicker than a stipe in the fungiform protrusions is formed. And then, pouring molten iron into the hub inner ring casting mold with the dried casting coating layer, so as to produce the hub inner ring with a plurality of convex structures.

For large bubbles which are distributed around and have higher uniformity and higher internal pressure, the breaking time is earlier, so that a channel generated by the breaking of the large bubbles and a mycorrhiza part formed by the fact that the inner surface of a coating layer of a casting is flushed to the periphery by the impact force generated during the breaking tend to fade away along with the action of a longer-time centrifugal force in the casting process, the side wall of the large bubbles is close to a smoother conical surface, and a table-shaped bulge in a bulge structure is correspondingly formed.

The function of the individual components of the coating is explained below:

the water is used as a solvent and has the functions of mixing all components and generating bubbles by vaporization on the preheated inner surface of the hub inner ring casting mold;

the sodium bentonite is used as a suspending agent and has the function of ensuring that the heat-insulating aggregate and the refractory aggregate are suspended in aqueous solution and cannot be precipitated and accumulated;

the diatomite is used as a thermal insulation aggregate, so that the heat energy is isolated, and the high temperature of liquid molten iron is prevented from being transferred to the mold, so that the temperature of the mold is prevented from being increased and deformed;

the quartz sand is used as refractory aggregate, plays a supporting role, is similar to a steel bar in concrete, is used for enhancing the strength of the coating and avoids holes generated by the surfactant from being washed away by molten iron and burnt;

the alkyl sulfate is used as a surfactant for enhancing the surface tension of water in the coating, so that when the coating contacts a high-temperature mold, water vapor formed by water in the coating is gathered together to form bubbles, and the bubbles are broken at the inner circular surface of the coating layer to a certain extent (when the internal pressure is greater than the surface tension).

Wherein if the diatomaceous earth is less than 15% by weight, the thermal insulation effect of the coating layer will be reduced, and if the diatomaceous earth is more than 25% by weight, the coating layer will have a higher viscosity and will not flow as desired. If the sodium bentonite is less than 4% by weight, the diatomaceous earth and quartz sand in the coating layer are easily precipitated and stacked, resulting in a decrease in the thermal insulation and heat retention properties of the coating layer. And if the sodium bentonite is more than 7% by weight, the swelling index and water absorption rate of the coating stratification are decreased.

In another preferred embodiment, when coating the coating, the rotating speed of the hub inner ring mold is controlled to be 700-1200r/min, and the temperature of the hub inner ring mold is controlled to be 200-300 ℃; and further, the coating is more uniformly distributed on the surface of the hub inner ring casting mold and is not easy to fall off.

When molten iron is poured into the hub inner ring casting mold, the rotating speed of the hub inner ring casting mold is 1000-1600r/min, so that the molten iron is attached to the inner wall of the coating under the action of centrifugal force to form a hollow pipe fitting. Under the action of centrifugal force, the hub inner ring casting mold can be well filled with molten iron along the radial direction, so that the convex structures 4 on the outer peripheral surface of the hollow cylinder of the hub inner ring 3 are more full. In addition, centrifugal force also helps to remove gas and impurities in the liquid metal, influences the crystallization process of the metal, and improves the mechanical properties and physical properties of castings.

In another preferred embodiment, the material of the hub inner ring comprises nodular cast iron, and the temperature when molten iron is poured is 1380-1450 ℃, so that the casting has better tensile strength and Brinell hardness, the energy consumption in the casting process can be relatively saved, and the manufacturing cost is reduced.

Specifically, when the material of the hub inner ring 3 includes nodular cast iron, the following relationship is provided between the molten iron temperature and the strength and hardness: within the range of 1300-1460 ℃, the tensile strength and the Brinell hardness value are increased along with the increase of the temperature of molten iron; within the range of 1460-1500 ℃, the tensile strength continues to increase along with the increase of the temperature of molten iron, but the Brinell hardness changes little; and in the range of 1500-1600 ℃, the tensile strength is increased along with the increase of the temperature of the molten iron, but the Brinell hardness is reduced. Furthermore, the wall thickness of the cast part also has a quantitative relationship with the pouring temperature: the greater the wall thickness of the casting, the lower the pouring temperature should be.

Therefore, when the temperature of molten iron is 1380-1450 ℃, the inner ring of the hub has higher Brinell hardness, meets the requirement of high hardness required by the contact of the inner ring of the hub and the outer ring of the bearing, and has enough tensile strength. In addition, the temperature of the 1380-1450 ℃ molten iron is lower than that of the 1300-1600 ℃ cast iron molten iron, so that the energy consumption in the casting process can be saved, and the manufacturing cost is reduced.

In a third aspect of the invention:

as shown in fig. 1, a hub assembly is provided, comprising the hub inner ring 3 of any of the previous embodiments, the hub assembly further comprising a hub 1 and a hub bearing 2. Wherein, the hub 1 is positioned at the periphery of the hub inner ring 3, and the hub 1 is provided with a bearing hole 11; the hub bearing 2 is positioned inside the hub inner ring 3, and the outer ring of the hub bearing 2 is fixedly arranged on the inner circumferential surface of the hollow cylinder of the hub inner ring 3; and, the hub 1 is formed on the outer peripheral surface of the hollow cylinder of the hub inner ring 3 by insert casting process, so that the joint surface of the hub 1 and the hub inner ring 3 has a plurality of concave structures matching with the plurality of convex structures.

By adding the hub inner ring 3 between the hub 1 and the hub bearing 2, the assembly precision of the hub bearing 2 can be improved through the matching connection between the hub inner ring 3 and the hub bearing 2; and through the mutual laminating of hub inner race 3 and bearing hole 11 on the wheel hub 1, can improve the surface rigidity of wheel hub bearing hole department, avoid the wheel hub bearing 2 directly to assemble the wearing and tearing that cause wheel hub 1 when inside in bearing hole 11 simultaneously.

And as described in the first aspect of the present invention, the convex structures and the concave structures can improve the thermal conductivity and the bonding strength between the hub and the hub inner ring.

In a preferred embodiment, the material of the hub 1 comprises a light alloy and the material of the hub inner ring 3 comprises an iron-carbon alloy. The hub 1 and the hub inner ring 3 in the invention are made of different materials, and compared with a hub component made of the same material, the hub component can be designed in a light weight mode, and specifically:

the hub 1 is mainly used to transmit loads between the wheel and the axle, and therefore has certain requirements on the strength and rigidity of the material. And the hub 1 is of a large size, having a large impact on the overall weight of the hub assembly. In general terms, the hub 1 should be made of light metal with high strength and rigidity, such as aluminum alloy, magnesium alloy, titanium alloy, etc. In view of manufacturing difficulty and cost, aluminum alloy is a preferred material.

The hub inner ring 3 is mainly used for installing and arranging the hub bearing 2 in the bearing hole 11, needs to bear acting force, friction force and heat dissipation of the hub bearing 2, is small in size, and has small influence on the total weight of the hub assembly, so that the density of materials can not be paid much attention, and more materials with high surface rigidity and excellent wear resistance, such as cast iron or alloy steel, can be considered.

In addition, the working temperature variation range of the hub bearing 2 is large, and the thermal deformation coordination problem of the matching surfaces of the hub bearing 2 and the hub inner ring 3 needs to be considered, so that the hub inner ring 3 can select a material with the same or similar thermal expansion coefficient as the outer ring material of the hub bearing 2, and the transition of the material performance between the hub bearing 2 and the hub bearing hole is realized.

In a fourth aspect of the invention:

a method of manufacturing a hub assembly is provided, comprising the steps of:

a) manufacturing the hub: arranging the manufactured hub inner ring at the position of a central hole of a hub casting mold, injecting the light alloy which is smelted into a liquid state into a cavity of the hub casting mold in an insert casting mode, and mechanically processing the hub to a target size after the light alloy is cooled and shaped in the hub casting mold and is demoulded to obtain the hub with the hub inner ring insert cast;

According to the hub assembly provided by the invention, different parts in the hub assembly are made of different materials, so that the structural strength requirement of the hub 1 is met, the weight of the hub 1 is reduced, and the fuel economy of the hub 1 is improved. In addition, the convex structures 4 and the concave structures are matched with each other through the insert casting process, the bonding strength and the bonding tightness among the parts in the hub assembly can be improved, and the working temperature of the hub bearing 2 is reduced.

In the process of embedding the hub into the inner ring of the hub, pressure is applied to the liquid light alloy in the cavity of the hub casting mold, the flow of the liquid light alloy can be promoted, the embedding effect is improved, the shape of the concave structure on the hub is fuller, and then the gap formed between the convex structure and the concave structure is reduced.

Thus, various embodiments of the present invention have been described in detail. It will be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that various changes may be made in the above embodiments or equivalents may be substituted for elements thereof without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. The utility model provides a hub inner circle, its characterized in that, hub inner circle (3) are hollow cylinder, hub inner circle (3) have a plurality of protruding structures (4), protruding structure (4) are followed the outer peripheral face of the hollow cylinder of hub inner circle (3) is outside protrusion.

2. The hub inner ring according to claim 1, characterized in that the protrusion structure (4) comprises a mushroom-shaped protrusion (41), and the mushroom-shaped protrusion (41) meets the following requirements:

the method comprises the following steps that a longitudinal section perpendicular to the axial direction is made on a hub inner ring (3), the longitudinal section passes through a convex structure (4) to form a longitudinal section graph of the convex structure (4), in the longitudinal section graph, a connecting line between the lowest points of two side boundaries of the convex structure is used as a convex root datum line (AB), the boundary distance between the two side boundaries of the longitudinal section graph is measured along the direction parallel to the convex root datum line (AB), the longitudinal section graph of the convex structure (4) is divided into at least two areas by at least one dividing line parallel to the convex root datum line, and the distance between the dividing line and the convex root datum line is between 1/3 and 2/3 of the height of the convex structure;

wherein a maximum boundary distance (D) of the longitudinal profile in at least one region farther from the protrusion root reference line (AB) is greater than a minimum boundary distance (D) of the longitudinal profile in at least one region closer to the protrusion root reference line (AB).

3. The hub inner ring according to claim 2, characterized in that the proportion of the mushroom-shaped projections (41) in the plurality of projection structures (4) is 35-95%.

4. The hub inner ring according to claim 2 or 3, characterized in that the projection structure (4) further comprises a mesa-shaped projection (42), the mesa-shaped projection (42) satisfying the following requirements:

the method comprises the following steps that a longitudinal section perpendicular to the axial direction is made on a hub inner ring (3), the longitudinal section passes through a convex structure (4) to form a longitudinal section graph of the convex structure (4), in the longitudinal section graph, a connecting line between the lowest points of two side boundaries of the convex structure is used as a convex root datum line (AB), and a boundary distance (C) between the two side boundaries of the longitudinal section graph is measured along a direction parallel to the convex root datum line;

wherein a boundary distance (C) of the longitudinal profile is constant or gradually decreased as a distance from the protrusion root reference line is gradually increased.

5. The hub inner ring according to claim 4, characterized in that the proportion of the mesa-shaped projections (42) in the plurality of projection structures (4) is 5% -65%.

6. The hub inner ring according to claim 1, characterized in that the average of the top surface areas of the raised structures (4) is between 0.1 and 3mm²And the surface of the top surface area is perpendicular to the radial direction of the hub inner ring (3).

7. The hub inner ring according to claim 1, characterized in that the height of the raised structures (4) has an average value of 0.3-1.0 mm.

8. The hub inner ring according to claim 1, characterized in that the average value of the distribution density of the plurality of raised structures (4) relative to the hub inner ring (3) is between 15 and 50/cm²。

9. A method for manufacturing an inner ring of a hub according to any one of claims 1 to 8, comprising the steps of:

keeping the hub inner ring casting mold rotating; and

10. The method of claim 9, wherein the coating comprises:

4 to 7 mass percent of sodium bentonite;

15-25% by mass of diatomite;

0-5% of 350-mesh quartz sand by mass percentage;

0.0005 to 0.01 mass percent of alkyl sulfate; and

the balance being water.

11. The method for manufacturing a hub inner ring according to claim 9, wherein when the coating material is coated, the rotation speed of the hub inner ring mold is controlled to be 700-1200r/min, and the temperature of the hub inner ring mold is controlled to be 200-300 ℃; and when molten iron is poured into the hub inner ring casting mold, controlling the rotating speed of the hub inner ring casting mold to be 1000-1600 r/min.

12. The method as claimed in claim 9, wherein the material of the hub inner ring comprises ductile iron, and the temperature of the molten iron is 1380-1450 ℃.

13. A hub assembly, comprising a hub inner ring (3) according to any one of claims 1-8, the hub assembly further comprising:

the hub (1) is positioned on the periphery of the hub inner ring (3), and the hub (1) is provided with a bearing hole (11); and

the hub bearing (2) is positioned in the hub inner ring (3), and the outer ring of the hub bearing (2) is fixedly arranged on the inner circumferential surface of the hollow cylinder of the hub inner ring (3);

the hub (1) is formed on the outer peripheral surface of the hollow cylinder of the hub inner ring (3) through an insert casting process, so that a plurality of concave structures matched with the plurality of convex structures are formed on the joint surface of the hub (1) and the hub inner ring (3).

14. A hub assembly according to claim 13, characterized in that the material of the hub (1) comprises a light alloy and the material of the hub inner ring (3) comprises an iron-carbon alloy.

15. A method of manufacturing a hub assembly according to any of claims 13-14, comprising the steps of:

a) manufacturing the hub: arranging the manufactured hub inner ring at the position of a central hole of a hub casting mold, injecting light alloy which is smelted into a liquid state into a cavity of the hub casting mold in an insert casting mode, and mechanically processing the hub to a target size after the light alloy is cooled and shaped in the hub casting mold and is demoulded to obtain the hub with the hub inner ring insert cast;

16. The method of manufacturing a hub assembly of claim 15, wherein the light alloy melted to a liquid state is injected into the cavity of the hub mold by pressure insert casting, and the liquid light alloy in the cavity of the hub mold is maintained at a constant temperature and pressure during the pressure insert casting until the liquid light alloy is completely solidified.