CN115121841B

CN115121841B - Center hole determination device and center hole determination method

Info

Publication number: CN115121841B
Application number: CN202210140456.2A
Authority: CN
Inventors: 义本明广
Original assignee: Komatsu NTC Ltd
Current assignee: Komatsu NTC Ltd
Priority date: 2021-03-25
Filing date: 2022-02-16
Publication date: 2025-03-18
Anticipated expiration: 2042-02-16
Also published as: JP2022149982A; DE102022106511A1; JP7588015B2; CN115121841A

Abstract

Provided are a center hole determination device and a center hole determination method capable of determining whether or not blank surfaces remain on both end portions of a crank shaft blank after cutting. The center hole determination device (20) is provided with an inertial main shaft acquisition unit (24), a determination unit (25), and a center hole determination unit (26). An inertia main shaft acquisition unit (24) acquires the inertia main shaft of the crankshaft blank (1) on the basis of the actual shape of the weight (CW). A determination unit (25) determines whether or not the blank surface of the front shaft (E1) remains after the crankshaft blank (1) has been cut, based on the actual shape of the front shaft (E1) and the principal axis of inertia. When it is determined that the blank surface of the front axle (E1) does not remain, a center hole determination unit (26) determines the center hole of the crankshaft blank (1) based on the principal axis of inertia.

Description

Center hole determination device and center hole determination method

Technical Field

The present invention relates to a center hole determination device and a center hole determination method.

Background

After forming a center hole in both end surfaces of a crankshaft blank formed by forging or casting, a crankshaft incorporated in an engine is subjected to blank surface cutting processing on the crankshaft blank with the center hole as a reference.

Patent document 1 discloses a method of determining a center hole in a crankshaft blank using the shape of a weight. Specifically, in patent document 1, the design shape of the weight is divided into a plurality of regions around the geometric center, and the center hole is determined based on the expansion/contraction ratio when the shape of each region is matched with the actual shape of the weight.

Prior art literature

Patent literature

Patent document 1 Japanese patent application laid-open (Kokai) No. 2018-179044

Disclosure of Invention

Technical problem to be solved by the invention

However, in the method of patent document 1, since the center hole is defined only by the shape of the weight in the crankshaft blank, when the blank surface of the crankshaft blank is cut with reference to the center hole, blank surfaces of both end portions (specifically, the front shaft and the rear flange) of the crankshaft blank may remain.

Therefore, it is intended to determine whether or not the blank surface remains at both end portions of the crankshaft blank even when the center hole is determined after cutting.

The present invention provides a center hole determination device and a center hole determination method capable of determining whether the blank surface of both end portions remains after a crankshaft blank is cut.

Technical scheme for solving technical problems

The center hole determining device of the present invention determines a center hole of a crankshaft blank having a weight located between a first end portion and a second end portion. The center hole determination device includes an inertial main shaft acquisition unit, a determination unit, and a center Kong Queding unit. The inertia main shaft acquisition unit acquires the inertia main shaft of the crankshaft blank based on the actual shape of the weight. The determination unit determines whether or not the blank surface of the first end portion remains after the crankshaft blank is cut, based on the actual shape of the first end portion and the principal axis of inertia. When it is determined that the blank surface of the first end portion is not left, the center hole determination unit determines the center hole of the crankshaft blank based on the principal axis of inertia.

Effects of the invention

According to the present invention, it is possible to provide a center hole determination device and a center hole determination method capable of determining whether or not a blank surface remains at both end portions after a crankshaft blank is cut.

Drawings

Fig. 1 is a perspective view of a crankshaft blank.

Fig. 2 is a schematic view showing the structure of a processing system of a crankshaft blank.

Fig. 3 is a schematic view showing the structure of the center hole determination device.

Fig. 4 is a diagram showing the design shape and the actual shape of the weight.

Fig. 5 is a diagram for explaining fitting of the design shape of the weight to the actual shape.

Fig. 6 is a diagram for explaining expansion and contraction of each divided region of the weight.

Fig. 7 is a diagram showing the divided regions of the weight.

Fig. 8 is a diagram for explaining a step of determining whether or not the blank surface of the front axle remains.

Fig. 9 is a flowchart for explaining the center hole determination method.

Detailed Description

(Crankshaft blank 1)

Fig. 1 is a perspective view showing the structure of a crankshaft blank 1. The crankshaft blank 1 is formed, for example, by forging or casting. The crankshaft blank 1 of the present embodiment is a crankshaft blank for an in-line 4-cylinder engine.

In fig. 1, the Z axis is the central axis of the crankshaft blank 1, the X axis is an axis perpendicular to the Z axis, and the Y axis is an axis perpendicular to the Z axis and the X axis.

The crankshaft blank 1 has a front shaft E1, a rear flange E2, eight weights CW (CW 1 to CW 8), four main journals J (J1 to J5), and four connecting rod journals P (P1 to P4).

In the crankshaft blank 1, a front shaft E1, a main journal J1, a balance weight CW1, a connecting rod journal P1, a balance weight CW2, a main journal J2, a balance weight CW3, a connecting rod journal P2, a balance weight CW4, a main journal J3, a balance weight CW5, a connecting rod journal P3, a balance weight CW6, a main journal J4, a balance weight CW7, a connecting rod journal P4, a balance weight CW8, a main journal J5, and a rear flange E2 are arranged in this order in the Z-axis direction.

The front axle E1 and the rear flange E2 are located at both end portions of the crankshaft blank 1. The front axle E1 and the rear flange E2 are examples of the "first end portion" and the "second end portion" of the present invention, respectively.

The front axle E1 has a first end surface S1 that forms a center hole in a later process. The rear flange E2 has a second end surface S2 where a center hole is formed in a subsequent step.

It is noted that the structure of the crankshaft blank 1 is not limited to that shown in fig. 1. The crankshaft blank 1 may have at least one weight CW and at least one of the front shaft E1 and the rear flange E2.

(Crankshaft processing System 100)

Next, a crankshaft processing system 100 according to the present embodiment will be described with reference to fig. 2. Fig. 2 is a schematic diagram showing the structure of the crankshaft processing system 100.

The crankshaft machining system 100 includes a center hole machining machine 10, a center hole determining device 20, and a crankshaft machining machine 30.

The center hole processing machine 10 includes an actual shape measuring unit 11 and a center hole processing unit 12.

The actual shape measuring unit 11 is an example of a measuring mechanism for measuring the actual shape of the crankshaft blank 1.

The actual shape measuring unit 11 includes, for example, a noncontact displacement meter such as a laser displacement meter, an infrared displacement meter, an LED type displacement sensor, or a contact displacement meter such as a work transformer. The actual shape measuring unit 11 measures the actual shapes of the front shaft E1, the rear flange E2, and the eight weights CW in the crankshaft blank 1 based on the measurement values from the displacement meters. As described later, the actual shapes of the eight weights CW are used to determine the principal axes of inertia, and the actual shapes of the front axle E1 and the rear flange E2 are used to determine whether or not the blank surfaces of the front axle E1 and the rear flange E2 remain after cutting.

Examples of the method of measuring the actual shape using the displacement meter include, but are not limited to, a method of measuring the actual shape using a fixed displacement meter while rotating the crankshaft blank 1, a method of measuring the actual shape while rotating the displacement meter around the fixed crankshaft blank 1, and a method of measuring the actual shape while linearly moving the displacement meter disposed so as to sandwich the crankshaft blank 1 from the left and right.

The actual shape measuring unit 11 may be a three-dimensional digitizer (image scanner) that generates the actual shape of the entire crankshaft blank 1 as three-dimensional shape data by measuring the measurement object from a plurality of different positions.

The center hole processing portion 12 processes the center hole defined by the center hole defining means 20 on the first and second end surfaces S1, S2 of the crankshaft blank 1.

The center hole determining device 20 is a processing device for determining the position of the center hole machined in the first and second end surfaces S1, S2 of the crankshaft blank 1. The center hole determination device 20 has CPU (Central Processing Unit) a, ROM (Read Only Memory) 20b, and RAM (Random Access Memory) c.

The ROM20b stores various programs and various information executed by the CPU20 a. In the present embodiment, the ROM20b stores a program of processing for determining the position of the center hole of the crankshaft blank 1. The ROM20b stores design shape data showing the design shapes of the front shaft E1, the rear flange E2, and the eight weights CW in the crankshaft blank 1. The RAM20c is used as a storage area for storing programs and data, or a work area for storing processing data in the CPU20 a.

The crankshaft processing machine 30 cuts the blank surface of the crankshaft blank 1 having the center hole processed by the center hole processing unit 12. The crankshaft processing machine 30 mainly cuts the blank surfaces of the front shaft E1, the rear flange E2, the weights CW, the connecting rod journals P, and the main journals J based on the design shape.

(Central hole determination device 20)

Fig. 3 is a schematic diagram showing the structure of the center hole determination device 20. The center hole determination device 20 includes an actual shape data acquisition unit 21, a expansion/contraction ratio calculation unit 22, a correction unit 23, a principal axis of inertia acquisition unit 24, a determination unit 25, and a center hole determination unit 26.

< Actual shape data acquisition section 21>

The actual shape data acquisition unit 21 acquires actual shape data indicating the actual shapes of the front shaft E1, the rear flange E2, and the eight weights CW in the crankshaft blank 1 from the actual shape measurement unit 11.

The actual shape data acquisition unit 21 transmits the actual shape data showing the actual shapes of the eight weights CW to the expansion/contraction ratio calculation unit 22, and transmits the actual shape data showing the actual shapes of the front axle E1 and the rear flange E2 to the determination unit 25.

< Expansion/contraction Rate calculation portion 22>

The expansion/contraction ratio calculation unit 22 acquires actual shape data indicating the actual shape of each weight CW from the actual shape data acquisition unit 21. The expansion/contraction ratio calculation unit 22 acquires design shape data indicating the design shape of each weight CW of the crankshaft blank 1 from the ROM20 b.

Fig. 4 is a schematic diagram showing the design shape (solid line) and the actual shape (dot ∈) of the weight CW.

As shown in fig. 4, the position and angle of the actual shape are shifted with respect to the position and angle of the design shape. In fig. 4, the design shape is shown in solid lines, but the actual design shape is indicated by a plurality of pole shoes. The number of polar coordinates is not particularly limited, and 360 can be set at an equal angle (1 degree) around the center P1 of the weight CW, for example.

Here, as shown in fig. 4, in the design shape, a plurality of divided regions DR are set around the center P1 of the weight CW. Each divided region is substantially fan-shaped. The number of divided regions DR is not particularly limited, but in fig. 4, 32 regions are set around the center P1 of the weight CW at equal angles (11.25 degrees). The center P1 of the weight CW is the geometric center of the weight CW in plan view. The design shape includes coordinates (x, y, z) of the center of gravity Q1 (only one center of gravity Q1 is shown in fig. 4) of each divided region DR, and the volume V of each divided region R. The expansion/contraction ratio calculation unit 22 stores the coordinates (x, y, z) of the center of gravity Q1 and the volume V in association with each other for all the divided regions DR. It is noted that X, Y, and Z representing coordinates correspond to the X-axis, Y-axis, and Z-axis of fig. 1.

Next, as shown in fig. 5, the expansion/contraction ratio calculation unit 22 uses the optimal fitting method, and moves and/or rotates the design shape to fit the actual shape, thereby finding a position where the sum of squares of errors between the design shape and the actual shape is minimized. The expansion/contraction ratio calculation unit 22 compares the center P1 of the weight CW before the best fitting with the center P2 of the weight CW after the best fitting, and calculates the positional displacement M1 in the X-axis direction, the positional displacement M2 in the Y-axis direction, and the angular displacement M3 around the Z-axis.

Next, as shown in fig. 5, the expansion/contraction ratio calculation unit 22 obtains coordinates (x ', y', z) of the center of gravity Q2 of each of the divided regions DR after the best fitting, using the positional displacement M1, the positional displacement M2, and the angular displacement M3. The expansion/contraction ratio calculation unit 22 stores the coordinates (x ', y', z) of the center of gravity Q2 of each of the divided regions DR after the best fitting in association with the volume V. It is noted that the z-coordinates of the center of gravity Q2 of each divided region DR after the best fitting are the same as those of the center of gravity Q1 of each divided region DR before the best fitting. The volume V of each divided region DR after the best fitting is the same as the volume V of each divided region DR before the best fitting.

Note that, in fig. 5, in order to show the positional relationship between the center of gravity Q1 and the center of gravity Q2, only one divided region DR in the design shape after the best fitting is shown, and in the design shape after the best fitting, 32 divided regions DR as shown in fig. 4 are also set.

Next, as shown in fig. 6 (a) and (b), the expansion/contraction ratio calculation unit 22 compares the best-fit divided region DR with the actual shape, and obtains an error value a of both in the radial direction around the center P2 of the best-fit weight CW. As shown in fig. 6 (c), the expansion/contraction ratio calculation unit 22 obtains the sum T (=s+a) of the entire length S of the divided region DR in the radial direction and the error value a, and further obtains the expansion/contraction ratio U (=t/S) by dividing the sum T by the entire length S. As described later, the expansion/contraction ratio U is used to expand and contract each divided region DR in the radial direction so as to match the actual shape of the weight CW. In the examples shown in fig. 6 (a) to (c), the actual-shape point is located radially outside the divided region DR, and therefore the expansion/contraction ratio U is larger than 1, but in the case where the actual-shape point is located radially inside the divided region DR, the expansion/contraction ratio U is smaller than 1.

< Correction portion 23>

The correction unit 23 corrects the coordinates (x ', y', z) of the center of gravity Q2 of each of the divided regions DR after the best fitting based on the expansion/contraction ratio U. Specifically, the correction unit 23 obtains correction coordinates (x '×u, y' ×u, z) of the center of gravity Q2 of each of the divided regions DR after expansion and contraction. The z-coordinate of the center of gravity Q2 after expansion and contraction is the same as the z-coordinate of the center of gravity Q2 before expansion and contraction.

The correction unit 23 corrects the volume V of each of the divided regions DR after the best fitting based on the expansion/contraction ratio U. Specifically, the correction unit 23 obtains the correction volume v×u ² of each of the expanded and contracted divided regions DR. The correction of the volume V of each divided region DR means correction of the mass (product value of the volume V and the material density) of each divided region DR.

The correction unit 23 multiplies the correction volume v×u ² by the material density α of the weight CW to obtain the correction mass M (=v×u ² ×α) of each divided region DR.

As described above, by expanding and contracting the size of the divided region DR based on the expansion and contraction rate U (expanding in fig. 6 (a) to (c)), the entire divided region DR can be expanded and contracted to the point of the actual shape in an equal ratio. This means that the design shape of the weight CW matches the actual shape in each divided region DR. Therefore, the actual shape of the weight CW can be easily and accurately reproduced.

The correction unit 23 obtains 32 sets of correction coordinates (x '×u, y' ×u, z) and correction mass M for each weight CW. Therefore, the correction coordinates (x '×u, y' ×u, z) and the correction mass M are combined in 32×8=256 groups (each eight weights CW 32 groups) for each crankshaft blank.

< Principal axis of inertia acquisition section 24>

As shown in fig. 7, the principal axis of inertia obtaining unit 24 obtains principal axes of inertia of 256 particles by solving a three-dimensional linear equation using 256 corrected coordinates (x '×u, y' ×u, z) of all divided regions DR of all weights CW as particles of corrected mass M under the condition that the product of inertia around the principal axis of inertia is 0 (zero).

The principal axis of inertia acquisition unit 24 sends the acquired principal axis of inertia to the determination unit 25 as the principal axis of inertia of the crankshaft blank 1.

< Determination section 25>

The determination unit 25 acquires actual shape data indicating the actual shapes of the front axle E1 and the rear flange E2 from the actual shape data acquisition unit 21. The determination unit 25 acquires the principal axis of inertia of the crankshaft blank 1.

The determination unit 25 determines whether or not the blank surface of the front axle E1 remains after the blank surface of the crankshaft blank 1 is cut in the crankshaft processing machine 30, based on the actual shape of the front axle E1 and the principal axis of inertia.

Specifically, the determination unit 25 calculates the minimum distance Rmin between the principal axis of inertia and the blank surface of the front axis E1, and then determines whether or not the design dimension R1 represented by the design shape is larger than the minimum distance Rmin. As shown in fig. 8 (a), when the design dimension R1 is larger than the minimum distance Rmin, the determination unit 25 determines that the blank surface of the front shaft E1 remains after cutting in the crank processing machine 30. As shown in fig. 8 (b), when the design dimension R1 is equal to or smaller than the minimum distance Rmin, the determination unit 25 determines that the blank surface of the front shaft E1 after cutting in the crank processing machine 30 does not remain.

The determination unit 25 determines whether or not the blank surface of the rear flange E2 remains after the blank surface of the crankshaft blank 1 is cut in the crankshaft processing machine 30, based on the actual shape of the rear flange E2 and the principal axis of inertia, as in the front shaft E1.

< Center Kong Queding part 26>

When the determination unit 25 determines that the blank surfaces of the front shaft E1 and the rear flange E2 do not remain, the center Kong Queding unit 26 determines the center hole of the crankshaft blank 1 based on the principal axis of inertia.

Specifically, the center Kong Queding determines the position of the center hole in each of the first and second end surfaces S1, S2 by bringing the z coordinates of each of the first and second end surfaces S1, S2 of the crankshaft blank 1 into the x and y formulas of the principal axis of inertia. Thereafter, the center Kong Queding section 26 transmits position data indicating the center hole to the center hole processing section 12.

On the other hand, when the determination unit 25 determines that at least one of the front shaft E1 and the rear flange E2 remains on the blank surface, the center Kong Queding unit 26 does not determine the positions of the center holes in the first and second end surfaces S1, S2 because the crankshaft blank 1 becomes a defective product even when the crankshaft processing machine 30 cuts the blank. Thereafter, the center Kong Queding section 26 sends instruction data indicating that the crankshaft blank 1 is to be removed from the production line to the center hole processing section 12.

(Center hole determination method)

Fig. 9 is a flowchart for explaining the center hole determination method.

In step S1, the actual shape data acquisition unit 21 acquires actual shape data indicating the actual shapes of the front shaft E1, the rear flange E2, and the eight weights CW in the crankshaft blank 1.

In step S2, the principal axis of inertia acquisition unit 24 acquires the principal axis of inertia of the crankshaft blank 1 based on the actual shape of each weight CW. In the present embodiment, the principal axis of inertia acquisition unit 24 acquires principal axes of inertia based on a combination of correction coordinates (x '×u, y' ×u, z) of the shape of each divided region DR calculated from the expansion/contraction ratio U when the actual shape of the weight CW is matched with the mass point of the correction mass M.

In step S3, the determination unit 25 determines whether or not the blank surfaces of the front shaft E1 and the rear flange E2 remain after the blank surfaces of the crankshaft blank 1 are cut based on the actual shapes of the front shaft E1 and the rear flange E2 and the principal axes of inertia. If it is determined that the blank surface of either the front axle E1 or the rear flange E2 does not remain, the process proceeds to step S4. When it is determined that the blank surface of either the front axle E1 or the rear flange E2 remains, the process proceeds to step S5.

In step S4, the center Kong Queding portion 26 determines the center hole of the crankshaft blank 1 based on the principal axis of inertia.

In step S5, since the crankshaft blank 1 is cut into a defective product, the center hole determination portion 26 does not determine the center hole.

(Modification of embodiment)

< Modification 1>

In the above embodiment, the principal axis of inertia acquisition unit 24 acquires the principal axis of inertia based on the combination of the correction coordinates (x '×u, y' ×u, z) of the shape of each divided region DR calculated from the expansion/contraction ratio U when the actual shape of the weight CW is matched with the mass point of the correction mass M. However, the method of acquiring the principal axis of inertia in the principal axis of inertia acquiring section 24 is not limited thereto. The principal axis of inertia acquisition unit 24 may acquire the principal axis of inertia of the crankshaft blank 1 based on the actual shape of the weight CW.

For example, as another method for obtaining the principal axis of inertia, a method of applying the best fit of the least squares method is given. Specifically, the least square center in each weight CW is calculated by comparing the actual shape and the designed shape of each weight CW with each other so that the least square axis passing through the least square center points on average is the principal axis of inertia.

< Modification example 2>

In the above embodiment, the determination unit 25 determines whether or not the blank surfaces of the front shaft E1 and the rear flange E2 remain after the blank surfaces of the crankshaft blank 1 are cut based on the actual shapes of the front shaft E1 and the rear flange E2 and the principal axes of inertia. However, the determination unit 25 may determine whether or not the surface of the blank remains only on one of the front shaft E1 and the rear flange E2, which is determined empirically that the surface of the blank is likely to remain.

< Modification example 3>

In the above embodiment, when it is determined that at least one of the blank surfaces of the front shaft E1 and the rear flange E2 remains, the center Kong Queding portion 26 does not determine the positions of the center holes in the first and second end surfaces S1, S2. However, the principal axis of inertia may be corrected when it is determined that at least one of the front axis E1 and the rear flange E2 remains on the blank surface. For example, the determination unit 25 may perform the determination again after moving the principal axis of inertia slightly in the opposite direction of the blank surface remaining area in the front axis E1 and the rear flange E2.

< Modification 4>

In the above embodiment, the crank processing system 100 has the center hole processing machine 10, the center hole determining device 20, and the crank processing machine 30, but the functional parts included in these can be appropriately separated or combined. For example, the center hole processing machine 10 may be provided with the actual shape measuring unit 11 and the center hole processing unit 12, but may be provided with other devices for the actual shape measuring unit 11 and the center hole processing unit 12.

Description of the reference numerals

1, A crankshaft blank;

10, a center hole processing machine;

A central hole determining device;

an actual shape data acquisition unit 21;

a expansion ratio calculation unit 22;

23, a correction part;

24, an inertial main shaft acquiring part;

25, a judging part;

a center hole determining section 26;

30, a crankshaft processing machine;

100, a crankshaft machining system.

Claims

1. A center hole determining device for determining a center hole of a crankshaft blank having a balancing weight located between a first end and a second end, the center hole determining device comprising:

An inertia principal axis acquisition unit, which acquires the inertia principal axis of the crankshaft blank based on the actual shape of the balancing block;

a determination unit that determines whether a surface of the first end portion remains after the crankshaft blank is cut based on an actual shape of the first end portion and the principal axis of inertia;

A center hole identifying unit identifies the center hole of the crankshaft blank based on the inertia principal axis when it is determined that the blank surface of the first end portion does not remain.

2. The center hole determination device according to claim 1, wherein:

The determination unit determines whether the surfaces of the first end portion and the second end portion remain after the crankshaft blank is cut based on the actual shapes of the first end portion and the second end portion and the principal axis of inertia.

When it is determined that the raw material surface of each of the first end portion and the second end portion does not remain, the center hole identifying unit identifies the center hole of the raw material crankshaft based on the principal axis of inertia.

3. A method for determining a center hole of a crankshaft blank having a balancing weight located between a first end and a second end, comprising:

An acquisition step of acquiring the inertia principal axis of the crankshaft blank based on the actual shape of the balancing block;

a determination step of determining whether a surface of the first end portion remains after the crankshaft blank is cut based on an actual shape of the first end portion and the principal axis of inertia;

The center hole determining step determines the center hole of the crankshaft blank based on the inertia principal axis when it is determined that the blank surface of the first end portion does not remain.

4. The method for determining a center hole according to claim 3, wherein:

In the determination step, based on the actual shapes of the first end portion and the second end portion and the principal axis of inertia, it is determined whether the surfaces of the first end portion and the second end portion remain after the crankshaft blank is cut.

In the center hole determining step, when it is determined that the raw material surface of each of the first end portion and the second end portion does not remain, the center hole of the raw material crankshaft is determined based on the principal axis of inertia.