CN117943514B - Small sand mould additive manufacturing device and manufacturing method - Google Patents

Abstract

The invention relates to the technical field of sand mould additive manufacturing, in particular to a small sand mould additive manufacturing device and a manufacturing method. Spreading a layer of basic sand grains on a printing platform by a sand spreading head, spraying an adhesive according to the overall structural shape of the sand mold of the layer by a glue spraying device, forming an initial printing layer after solidification, cutting and crushing areas needing to be replaced with different sand grains on the initial printing layer by a milling cutter on a fixed-point milling device, sucking away the cut crushed grains by the fixed-point sand sucking device, spreading the corresponding types of sand grains again in the corresponding areas according to design requirements, spraying the adhesive matched with the newly-spread sand grains according to the sand grain types by the glue spraying device, forming a final printing layer after solidification, and leveling the boundaries of the areas of the newly-spread sand grains by the fixed-point milling device. And printing layer by layer until the whole sand mould is finished.

Description

Small sand mould additive manufacturing device and manufacturing method

Technical Field

The invention relates to the technical field of sand mould additive manufacturing, in particular to a small sand mould additive manufacturing device and a manufacturing method.

Background

The self-adaptive casting sand mould (composite sand mould) can realize the self-adaptation of the casting mould to the casting cooling solidification process, and promote the whole casting to be uniformly solidified and transformed. The self-adaptive casting sand mould is characterized in that different modeling materials are selected for different parts of the casting, the modeling materials comprise sand grains and binding agents, wherein the sand grains mainly comprise four main sand varieties of silica sand, zircon sand, chromite sand and steel shot sand mixing, and the binding agents comprise four typical binding agents of furan resin, alkaline phenolic resin, urethane resin and fat hardening modified water glass. Different sand grains can be used for the self-adaptive sand mold, for example, chromite sand (high refractoriness and strong chilling capability) can be used for hot joints, corners and parts with poor heat dissipation conditions; the steel shot sand mixing is used for controlling the solidification process of the casting, so that the uniform shrinkage rate of a casting mould unit is achieved, the whole casting uniformly shrinks, and the self-adaption of the casting mould to the solidification process of the casting is achieved.

The self-adaptive casting sand mould manufactured by the traditional method needs to be firstly processed in blocks according to the sand types, then sand blocks are combined, and then modeling processing combination is carried out, so that the production period is long, the manufacturing process is complex, the sand mould error is large, the subsequent casting processing is influenced, the optimal processing path cannot be optimized, and the processing flexibility and intelligence are lacked. Particularly for small sand types, the dicing process is more difficult.

In view of the above problems, the present inventors have finally achieved the present invention through long-time studies and practices.

Disclosure of Invention

In order to solve the technical problems, the invention provides a small sand mould additive manufacturing device and a manufacturing method, which improve the precision and the production efficiency.

The invention adopts the technical scheme that:

In one aspect, a small sand mold additive manufacturing apparatus is provided, comprising: the device comprises a printing platform, a sanding beam, a printing beam and a sand changing beam;

The printing platform is horizontally arranged and used for receiving and bearing sand grains to form a sand mold; the sand spreading beam is arranged above the printing platform and can move along the longitudinal direction and the horizontal direction, and a sand spreading head is arranged on the sand spreading beam and is used for spreading basic sand grains layer by layer on the printing platform; the printing beam is arranged above the printing platform and can move along the horizontal direction, and a glue spraying device is arranged on the printing beam and is used for spraying a binder in a first preset area of a single basic sand grain layer so as to form an initial printing layer; the sand changing beam is arranged above the printing platform and can move along the horizontal direction, a fixed-point milling device and a fixed-point sand sucking and spreading device are arranged on the sand changing beam, the fixed-point milling device is used for smashing at least one second preset area on the initial printing layer, and the fixed-point sand sucking and spreading device is used for sucking away smashed particles in the second preset area and spreading sand grains different from basic sand grains in the second preset area;

The glue spraying device is also used for spraying an adhesive in the second preset area so as to form a final printing layer containing different types of sand grains.

Further, the fixed-point milling device is further configured to mill along an outline outside a second preset area of the upper surface of the final printed layer, so as to ensure that the upper surface of the final printed layer is planar.

Further, the fixed-point sand sucking and paving device comprises a gas circuit box and a sand sucking and paving head; the sand sucking and spreading head is arranged at the lower end of the air channel box, and the air channel box is connected to the sand exchanging beam and can drive the sand sucking and spreading head to longitudinally move relative to the sand exchanging beam.

Further, the sand sucking and spreading head comprises a mouth changing rotary table and a plurality of sucking and spreading nozzles with different sizes and/or shapes;

the mouth changing turntable comprises a circular truncated cone-shaped base body and a motor driving mechanism, wherein the circular truncated cone-shaped base body is provided with a main body support and an annular conical surface surrounding the main body support, the annular conical surface can rotate relative to the main body support, the motor driving mechanism is arranged on the main body support, and the motor driving mechanism is used for driving the annular conical surface to rotate; the suction nozzles are arranged on the annular conical surface at intervals.

Further, an air channel in the air channel box is respectively connected with the sand sucking pneumatic system and the sand paving pneumatic system in a second preset area, and a nozzle is arranged at the bottom of the air channel box; the side surface of the gas circuit box is longitudinally provided with a cylinder and a guide rail, the mouth changing turntable is hinged with a telescopic rod of the cylinder through a connecting rod, a guide wheel is arranged on the mouth changing turntable, and a reset spring is connected between the mouth changing turntable and the gas circuit box;

When the telescopic rod of the air cylinder is positioned at the first position, one suction laying nozzle on the annular conical surface is in sealing fit with the nozzle opening; when the telescopic rod of the air cylinder extends downwards to a second position, the reset spring is stretched, and the suction laying nozzle and the nozzle opening are completely separated; when the telescopic rod of the air cylinder continues to extend downwards to a third position, the reset spring is further stretched, the mouth changing rotary disc is overturned outwards under the cooperation of the guide wheel and the guide rail, and the motor driving mechanism drives the annular conical surface to rotate, so that the sucking and spreading mouth on the mouth changing rotary disc is subjected to transposition.

Further, a sand blocking groove is formed in the main body support of the mouth changing turntable, and an openable bottom plate is arranged at the bottom of the sand blocking groove; a spiral wind gathering groove line is formed on the inner wall of the air channel in the air channel box;

When the telescopic rod of the air cylinder stretches out to a third position, the sand blocking groove is positioned right below the air joint opening and is in a horizontal state, at the moment, the air joint opening of the air circuit is exhausted downwards, residual sand in the air circuit is cleaned, and blown sand is collected by the sand blocking groove.

Further, the sand suction pneumatic system comprises a sand suction electromagnetic control valve, a high-pressure sand suction pump and a sand collecting box which are sequentially connected in series; the second preset area sand paving pneumatic system comprises a plurality of parallel sand paving air circuits, each sand paving air circuit comprises a sand paving electromagnetic control valve, a high-pressure sand paving pump and a sand paving box which are sequentially connected in series, and different types of sand grains are filled in each sand paving box; the glue spraying device is connected with a plurality of binder sources, and adapted binders are sprayed according to different sand grains.

Further, two sides of the printing platform are respectively provided with a movable beam rail;

Two ends of the sand spreading beam are respectively connected with the two first upright posts in a sliding manner, two ends of the sand changing beam are respectively and fixedly connected with the two second upright posts, and two ends of the printing beam are respectively and fixedly connected with the two third upright posts;

the bottoms of the first upright post, the second upright post and the third upright post are respectively connected with the movable beam rail in a sliding manner.

Further, the small sand mould additive manufacturing device also comprises a sand mould loading and unloading rail which is in an I-shaped structure and comprises a longitudinal rail and two transverse rails; the bottom of the printing platform is in sliding connection with the sand mold loading and unloading rail; the printing platform comprises a drying platform, an air blowing cleaning platform and a common platform, wherein an electric heating rod is arranged in the drying platform, and an air blowing device is arranged on one side of the table top of the air blowing cleaning platform;

And (3) selecting one of a drying platform, a blowing cleaning platform and a common platform according to the property of the sand mould, feeding the sand mould into the longitudinal rail, entering a printing position for printing, stopping the other platforms on the transverse rail, and moving the platform carrying sand mould after printing from the longitudinal rail to the transverse rail for stopping.

On the other hand, the invention provides a sand mould additive manufacturing method, which adopts the small sand mould additive manufacturing device and comprises the following steps:

step 1: designing a sand mold three-dimensional model according to the geometric characteristics of the casting; carrying out block design on the designed sand mould three-dimensional model according to the performance requirement of the casting; wherein each divided sand block adopts one modeling sand grain, the whole sand mould adopts at least two modeling sand grains, and one modeling sand grain with the largest use amount in the whole sand mould is taken as a base sand grain;

Step 2: carrying out layering treatment on the three-dimensional modeling of the sand mold designed in a partitioning way, wherein the heights of all layers are the same, so that sand mold data of all layers are obtained, and the sand mold data of all layers comprise first preset area data and second preset area data;

step 3: paving a layer of basic sand grains on the printing platform through the height of the sand paving head of the sand paving Liang Diaojie;

Step 4: the glue spraying device uniformly sprays a binder in a first preset area on the paved base sand layer, and an initial printing layer is formed after solidification;

Step 5: the fixed-point milling device cuts and crushes a second preset area of the initial printing layer, wherein the second preset area is positioned in the first preset area;

Step 6: the fixed-point sand sucking and spreading device sucks all the crushed particles in the second preset area, and then spreads a layer of sand different from the basic sand in the second preset area;

Step 7: the glue spraying device sprays a binder in a second preset area, and a final printing layer is formed after solidification;

Step 8: the fixed-point milling device mills along the outline outside the second preset area on the upper surface of the final printing layer to ensure that the upper surface of the final printing layer is a plane;

Step 9: and (3) lifting the sanding head by one layer, and repeating the steps 3-8 until the sand mold is completed.

Compared with the prior art, the invention has the beneficial effects that:

1. the manufacturing device of the invention realizes the printing of various sand grain structures of the self-adaptive casting sand mold by cutting and changing the sand on the initial printing layer at fixed points.

2. The glue spraying device can automatically spray the corresponding adhesive according to the sand type.

3. The fixed-point sand sucking and paving device with the unique structure can be used for quickly replacing the sucking and paving nozzle, so that the production efficiency is greatly improved, and the processing precision is improved.

4. The sand blocking structure on the mouth changing turntable can prevent sand particles sprayed out during the cleaning of the air passage from polluting the printing layer.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view showing the overall structure of a small sand mold additive manufacturing apparatus according to an embodiment of the present invention;

FIG. 2 shows a schematic structural view of a sanding beam portion of an embodiment of the present invention;

FIG. 3 shows a schematic structural view of a sand changing beam portion of an embodiment of the present invention;

fig. 4 shows a schematic structural view of a print beam portion of an embodiment of the present invention;

FIG. 5 shows a structural state diagram of the fixed point sand sucking and paving device according to the embodiment of the invention when the cylinder telescopic rod is positioned at the first position;

FIG. 6 shows a structural state diagram of the fixed point sand sucking and paving device according to the embodiment of the invention when the cylinder telescopic rod is positioned at the second position;

FIG. 7 shows a structural state diagram of the fixed point sand sucking and paving device according to the embodiment of the present invention when the cylinder expansion link is located at the third position;

Fig. 8 illustrates a schematic structural view of a drying platform according to an embodiment of the present invention;

Fig. 9 shows a schematic structural view of an air-blowing cleaning platform according to an embodiment of the present invention.

Detailed Description

The above and further technical features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. indicate or are based on the orientation or positional relationship shown in the drawings, merely for convenience of description of the present invention, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" is at least two unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature "above," "over" and "on" a second feature may be a first feature directly above or obliquely above the second feature, or simply indicate that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

Each of the adaptive sand molds will use a different combination of sand and binder to make the mold, and such adaptive sand molds typically consist of three to four types of sand depending on the mold requirements. The small sand type manufacturing device is a manufacturing device with a working table ranging from 1000mm×1000mm to 1500mm×2000mm, and the manufacturing device of the present invention is suitable for small sand type.

As shown in fig. 1 to 4, in the present embodiment, the printing platform is horizontally disposed for receiving and carrying sand grains to construct a sand mold. The sand-spreading beam 1 is arranged above the printing platform and can be displaced along the longitudinal direction and the horizontal direction, and is provided with a sand-spreading head 11, wherein the sand-spreading head 11 is used for spreading basic sand grains layer by layer on the printing platform. The printing beam 3 is arranged above the printing platform and can be displaced in the horizontal direction, and the glue spraying device 31 is arranged on the printing beam, and the glue spraying device 31 is used for spraying an adhesive in a first preset area of the single basic sand grain layer so as to form an initial printing layer. The sand changing beam 2 is arranged above the printing platform and can move along the horizontal direction, a fixed-point milling device 21 and a fixed-point sand sucking and paving device 22 are arranged on the sand changing beam, the fixed-point milling device 21 is used for smashing at least one second preset area on an initial printing layer, and the fixed-point sand sucking and paving device 22 is used for sucking away smashed particles in the second preset area and paving sand different from basic sand in the second preset area. The glue spraying device 31 is also used to spray adhesive in a second predetermined area to form a final printed layer containing different types of sand grains.

In other words, the sanding head 11 lays a layer of base sand on the printing platform; the glue spraying device 31 sprays the adhesive according to the overall structure shape of the sand mould of the layer, and forms an initial printing layer after solidification; the milling cutter 211 on the fixed-point milling device 21 cuts and pulverizes the areas on the initial printing layer, which need to be replaced by different types of sand grains, and the fixed-point sand sucking and spreading device 22 sucks away the cut broken grains and spreads the corresponding types of sand grains again in the corresponding areas according to the design requirement; the glue spraying device 31 sprays an adhesive adapted thereto on newly laid sand grains according to the sand grain type, and after curing, a final printing layer is formed, which contains a plurality of sand grains and adhesive. In order to ensure the flatness of the printed layer, the fixed-point milling device 21 can level the boundary of the areas where different sand grains are re-paved, so that the occurrence of sand accumulation protrusions is avoided. And then each working head is lifted by one layer to print the next layer when working. Thus, according to the sand mould data of each printing layer, printing is carried out layer by layer until the whole sand mould is completed.

Referring to fig. 2 to 4, two sides of the printing platform are respectively provided with a movable beam track 4, two ends of the sanding beam 1 are respectively in sliding connection with two first upright posts 10, two ends of the sand changing beam 2 are respectively in fixed connection with two second upright posts 20, and two ends of the printing beam 3 are respectively in fixed connection with two third upright posts 30. The bottoms of the first upright post 10, the second upright post 20 and the third upright post 30 are respectively in sliding connection with the movable beam rail 4, and then the upright posts can horizontally displace along the sliding rail, so that the beams are driven to horizontally move. Wherein, the sanding roof beam 1 can carry out elevating movement along first stand 10, trades sand roof beam 2 and prints roof beam 3 and fix respectively on second stand 20 and third stand 30, can't go up and down, and fixed point milling device 21, fixed point inhale sanding device 22 and spouts mucilage binding and put 31 self and can adjust the working height of its working head.

As shown in fig. 1, 8 and 9, in some embodiments, the bottom of the printing platform is slidably connected to a sand mold loading and unloading rail 5, which is in an i-shaped structure and includes one longitudinal rail 51 and two transverse rails 52, and the longitudinal rail 51 is disposed between the two movable beam rails 4. The printing platform is divided into a plurality of types, including a drying platform 100, an air blowing cleaning platform 300 and a common platform 200, wherein an electric heating rod 101 is arranged in the drying platform 100, and an air blowing device 301 is arranged on one side of the table top of the air blowing cleaning platform 300. One of the drying platform 100, the blowing cleaning platform 300 and the common platform 200 is selected according to the property of the sand mould, and is sent into the longitudinal rail 51, enters a printing position for printing, the rest platforms are stopped on the transverse rail, and the platform carrying sand mould after printing is moved from the longitudinal rail 51 to the transverse rail 52 for stopping.

As shown in fig. 3 and 5 to 7, the fixed-point sand sucking and spreading device 22 includes a gas path box and a sand sucking and spreading head 221. The sand sucking and spreading head 221 is installed at the lower end of the air channel box. The air channel box is connected to the sand changing beam 2 and can drive the sand sucking and spreading head 221 to longitudinally move relative to the sand changing beam 2. The sanding head 221 includes a mouth changing carousel, a plurality of different sized and/or shaped sanding nozzles 225. The size and shape of the region (second preset region) to be changed are different, and different suction nozzles 225 are required to suck and lay the region, such as a corner, according to actual situations. How to quickly change ports is a critical issue.

The mouth changing turntable comprises a truncated cone-shaped substrate and a motor driving mechanism, wherein the truncated cone-shaped substrate is provided with a main body support and an annular conical surface 2213 surrounding the main body support, the annular conical surface 2213 can rotate relative to the main body support, the motor driving mechanism is arranged on the main body support, and the motor driving mechanism is used for driving the annular conical surface 2213 to rotate. A plurality of suction nozzles 225 are arranged on the annular conical surface at intervals. The bottom of the air channel 229 of the air channel box is provided with a nozzle opening for sealing and abutting with the suction laying nozzle 225. The side of the air channel box is longitudinally provided with an air cylinder 222 and a guide rail 228, the mouth changing turntable is hinged with the telescopic rods of the air cylinder 222 through connecting rods 223 and 224, a guide wheel 226 is arranged on the mouth changing turntable, and a reset spring 227 is connected between the mouth changing turntable and the air channel box.

As shown in fig. 5, when the telescopic rod of the air cylinder 222 is in the first position, under the combined action of the air cylinder 222 and the return spring 227, a suction nozzle 225 on the annular conical surface 2213 is in sealing engagement with the nozzle opening.

As shown in fig. 6, when the telescopic rod of the air cylinder 222 is extended downward to the second position, the whole mouth changing turntable is moved downward, the return spring 227 is stretched, and the suction nozzle 225 is completely separated from the mouthpiece.

As shown in fig. 7, when the telescopic rod of the air cylinder 222 continues to extend downwards to the third position, the guide wheel 226 is located at the protrusion of the guide rail 228, the return spring is further stretched, the mouth changing turntable is turned outwards under the cooperation of the guide wheel and the guide rail, and the motor driving mechanism drives the annular conical surface 2213 to rotate, so that the suction laying nozzle 225 on the mouth changing turntable is changed. The cylinder 222 is then raised, the port changing turntable is turned inwards and raised for resetting, so that the different suction paving nozzles 225 are in sealing engagement with the nozzle ports, and quick port changing is completed.

It should be noted that, because the sand replacement needs higher precision, in order to make the action point of the fixed-point sand sucking and spreading device 22 more concentrated during sand sucking and spreading, a spiral wind gathering groove line 2291 is formed on the inner wall of the air channel 229, which makes the formation of a rotating air flow therein more beneficial to sand sucking and spreading, but also makes the sand remaining on the inner wall of the air channel 229 easy, and makes the sand to be spread easily mixed with other sand during sand replacement, thereby affecting the performance of the self-adaptive sand mold. The air circuit 229 needs to be cleaned during the exchange of the suction nozzle 225.

Specifically, the main body support of the mouth changing turntable comprises an outer bottom plate 2211 and an inner conical ring 2212 which are connected, and an annular conical surface 2213 is positioned between the outer bottom plate 2211 and the inner conical ring 2212. The annular tapered surface 2213 may rotate and the outer base 2211 and inner tapered ring 2212 may not. The lower end of the inner cone 2212 is provided with a sand blocking groove, and the bottom of the sand blocking groove is provided with a bottom plate 2214 which can be opened and closed. When the telescopic rod of the air cylinder 222 extends to the third position, the sand blocking groove is positioned right below the nozzle opening and is in a horizontal state, the nozzle opening of the air circuit is exhausted downwards at the moment, residual sand in the air circuit is cleaned, and blown sand is collected by the sand blocking groove. The bottom plate 2214 may be opened to remove sand when too much sand is present in the sand trap.

The gas circuit 229 in the gas circuit box is respectively connected with a sand sucking pneumatic system and a second preset area sand paving pneumatic system, the sand sucking pneumatic system is used for providing power for sucking away cut particles, and the second preset area sand paving pneumatic system is used for providing power for paving different sand grains in the second preset area and switching different sand sources. Specifically, the sand suction pneumatic system comprises a sand suction electromagnetic control valve, a high-pressure sand suction pump and a sand collecting box which are sequentially connected in series. The second preset area sand paving pneumatic system comprises a plurality of parallel sand paving air circuits, each sand paving air circuit comprises a sand paving electromagnetic control valve, a high-pressure sand paving pump and a sand paving box which are sequentially connected in series, and different types of sand grains are filled in each sand paving box. It will be appreciated that the glue spray device is also connected to a plurality of sources of adhesive, with the adhesive being adapted to be sprayed according to the sand grain.

In another embodiment, a sand additive manufacturing method adopting the device is provided, which comprises the following steps:

1: designing a sand mold three-dimensional model according to the geometric characteristics of the casting; carrying out block design on the designed sand mould three-dimensional model according to the performance requirement of the casting; wherein each divided sand block adopts one modeling sand grain, the whole sand mould adopts at least two modeling sand grains, and one modeling sand grain with the largest use amount in the whole sand mould is taken as a base sand grain;

2: carrying out layering treatment on the three-dimensional modeling of the sand mold designed in a partitioning way, wherein the heights of all layers are the same, so that sand mold data of all layers are obtained, and the sand mold data of all layers comprise first preset area data and second preset area data;

3: adjusting the height of a sand spreading head through a sand spreading beam, and spreading a layer of basic sand grains on a printing platform;

4: the glue spraying device is adjusted to a proper height, the glue spraying device uniformly sprays a binder in a first preset area on the paved base sand grain layer, and an initial printing layer is formed after solidification;

5: cutting and crushing a second preset area of the initial printing layer by the fixed-point milling device, wherein the second preset area is positioned in the first preset area;

6: the fixed-point sand sucking and spreading device is adjusted to a proper height, firstly, the fixed-point sand sucking and spreading device sucks all the crushed particles in the second preset area, and then a layer of sand grains different from the basic sand grains are paved in the second preset area;

7: the glue spraying device sprays a binder in a second preset area, and a final printing layer is formed after solidification;

8: milling along the outline outside the second preset area of the upper surface of the final printing layer by a fixed-point milling device, so as to ensure that the upper surface of the final printing layer is a plane;

9: and (3) raising the sand laying head by one layer of height, and repeating the steps 3-8 until the sand mould is completed.

The foregoing description of the preferred embodiment of the invention is merely illustrative of the invention, and is not intended to be limiting. The structure, connection mode and the like of each component in the invention can be changed, and all equivalent changes and improvements performed on the basis of the technical scheme of the invention are not excluded from the protection scope of the invention.

Claims (7)

1. A small-size sand mould additive manufacturing device, characterized by comprising: the device comprises a printing platform, a sanding beam, a printing beam and a sand changing beam;

The printing platform is horizontally arranged and used for receiving and bearing sand grains to form a sand mold; the sand spreading beam is arranged above the printing platform and can move along the longitudinal direction and the horizontal direction, and a sand spreading head is arranged on the sand spreading beam and is used for spreading basic sand grains layer by layer on the printing platform; the printing beam is arranged above the printing platform and can move along the horizontal direction, and a glue spraying device is arranged on the printing beam and is used for spraying a binder in a first preset area of a single basic sand grain layer so as to form an initial printing layer; the sand changing beam is arranged above the printing platform and can move along the horizontal direction, a fixed-point milling device and a fixed-point sand sucking and spreading device are arranged on the sand changing beam, the fixed-point milling device is used for smashing at least one second preset area on the initial printing layer, and the fixed-point sand sucking and spreading device is used for sucking away smashed particles in the second preset area and spreading sand grains different from basic sand grains in the second preset area;

The glue spraying device is also used for spraying a binder in the second preset area so as to form a final printing layer containing sand grains of different types;

The fixed-point sand sucking and paving device comprises a gas circuit box and a sand sucking and paving head; the sand sucking and spreading head is arranged at the lower end of the air channel box, and the air channel box is connected to the sand exchanging beam and can drive the sand sucking and spreading head to longitudinally move relative to the sand exchanging beam; the sand sucking and spreading head comprises a mouth changing rotary table and a plurality of sucking and spreading nozzles with different sizes and/or shapes; the mouth changing turntable comprises a circular truncated cone-shaped base body and a motor driving mechanism, wherein the circular truncated cone-shaped base body is provided with a main body support and an annular conical surface surrounding the main body support, the annular conical surface can rotate relative to the main body support, the motor driving mechanism is arranged on the main body support, and the motor driving mechanism is used for driving the annular conical surface to rotate; the suction nozzles are arranged on the annular conical surface at intervals;

The air channel in the air channel box is respectively connected with the sand sucking pneumatic system and the sand paving pneumatic system in a second preset area, and the bottom of the air channel box is provided with a nozzle; the side surface of the gas circuit box is longitudinally provided with a cylinder and a guide rail, the mouth changing turntable is hinged with a telescopic rod of the cylinder through a connecting rod, a guide wheel is arranged on the mouth changing turntable, and a reset spring is connected between the mouth changing turntable and the gas circuit box; when the telescopic rod of the air cylinder is positioned at the first position, one suction laying nozzle on the annular conical surface is in sealing fit with the nozzle opening; when the telescopic rod of the air cylinder extends downwards to a second position, the reset spring is stretched, and the suction laying nozzle and the nozzle opening are completely separated; when the telescopic rod of the air cylinder continues to extend downwards to a third position, the reset spring is further stretched, the mouth changing rotary disc is overturned outwards under the cooperation of the guide wheel and the guide rail, and the motor driving mechanism drives the annular conical surface to rotate, so that the sucking and spreading mouth on the mouth changing rotary disc is subjected to transposition.

2. A small sand mould additive manufacturing apparatus as claimed in claim 1, wherein the fixed point milling means is further arranged to mill along a contour outside a second predetermined area of the upper surface of the final printed layer to ensure that the upper surface of the final printed layer is planar.

3. The small sand mould additive manufacturing device according to claim 2, wherein a sand blocking groove is formed in a main body support of the port changing turntable, and an openable bottom plate is arranged at the bottom of the sand blocking groove; a spiral wind gathering groove line is formed on the inner wall of the air channel in the air channel box;

When the telescopic rod of the air cylinder stretches out to a third position, the sand blocking groove is positioned right below the air joint opening and is in a horizontal state, at the moment, the air joint opening of the air circuit is exhausted downwards, residual sand in the air circuit is cleaned, and blown sand is collected by the sand blocking groove.

4. A small sand mould additive manufacturing device as claimed in claim 3, wherein the sand sucking pneumatic system comprises a sand sucking electromagnetic control valve, a high-pressure sand sucking pump and a sand collecting box which are sequentially connected in series; the second preset area sand paving pneumatic system comprises a plurality of parallel sand paving air circuits, each sand paving air circuit comprises a sand paving electromagnetic control valve, a high-pressure sand paving pump and a sand paving box which are sequentially connected in series, and different types of sand grains are filled in each sand paving box; the glue spraying device is connected with a plurality of binder sources, and adapted binders are sprayed according to different sand grains.

5. A small sand mould additive manufacturing apparatus as claimed in any one of claims 2-4,

Two sides of the printing platform are respectively provided with a movable beam track;

Two ends of the sand spreading beam are respectively connected with the two first upright posts in a sliding manner, two ends of the sand changing beam are respectively and fixedly connected with the two second upright posts, and two ends of the printing beam are respectively and fixedly connected with the two third upright posts;

the bottoms of the first upright post, the second upright post and the third upright post are respectively connected with the movable beam rail in a sliding manner.

6. A small sand mould additive manufacturing device as claimed in claim 5, further comprising a sand mould loading and unloading rail, wherein the sand mould loading and unloading rail is in an i-shaped structure and comprises a longitudinal rail and two transverse rails; the bottom of the printing platform is in sliding connection with the sand mold loading and unloading rail; the printing platform is divided into a drying platform, an air blowing cleaning platform and a common platform, wherein an electric heating rod is arranged in the drying platform, and an air blowing device is arranged on one side of the table top of the air blowing cleaning platform;

And (3) selecting one of a drying platform, a blowing cleaning platform and a common platform according to the property of the sand mould, feeding the sand mould into the longitudinal rail, entering a printing position for printing, stopping the other platforms on the transverse rail, and moving the platform carrying sand mould after printing from the longitudinal rail to the transverse rail for stopping.

7. A sand mould additive manufacturing method, characterized in that a small sand mould additive manufacturing device according to claim 2 is adopted, comprising the following steps:

step 1: designing a sand mold three-dimensional model according to the geometric characteristics of the casting; carrying out block design on the designed sand mould three-dimensional model according to the performance requirement of the casting; wherein each divided sand block adopts one modeling sand grain, the whole sand mould adopts at least two modeling sand grains, and one modeling sand grain with the largest use amount in the whole sand mould is taken as a base sand grain;

Step 2: carrying out layering treatment on the three-dimensional modeling of the sand mold designed in a partitioning way, wherein the heights of all layers are the same, so that sand mold data of all layers are obtained, and the sand mold data of all layers comprise first preset area data and second preset area data;

step 3: paving a layer of basic sand grains on the printing platform through the height of the sand paving head of the sand paving Liang Diaojie;

step 4: the glue spraying device is adjusted to a proper height, a binding agent is uniformly sprayed in a first preset area on the paved base sand grain layer, and an initial printing layer is formed after solidification;

Step 5: the fixed-point milling device cuts and crushes a second preset area of the initial printing layer, wherein the second preset area is positioned in the first preset area;

step 6: the fixed-point sand sucking and spreading device is adjusted to a proper height, firstly, all the crushed particles in the second preset area are sucked away, and then a layer of sand grains different from the basic sand grains are paved in the second preset area;

Step 7: the glue spraying device sprays a binder in a second preset area, and a final printing layer is formed after solidification;

Step 8: the fixed-point milling device mills along the outline outside the second preset area on the upper surface of the final printing layer to ensure that the upper surface of the final printing layer is a plane;

Step 9: and (3) lifting the sanding head by one layer, and repeating the steps 3-8 until the sand mold is completed.