CN115533026A

CN115533026A - Method for casting sand mold by laser processing and laser processing device

Info

Publication number: CN115533026A
Application number: CN202211165517.7A
Authority: CN
Inventors: 李锋军; 苏建新; 常云朋; 李菲; 许海铎; 张杰琼; 王世杰; 张益博; 张淑霞; 李平; 任凤章
Original assignee: First Tractor Co Ltd
Current assignee: First Tractor Co Ltd
Priority date: 2022-09-23
Filing date: 2022-09-23
Publication date: 2022-12-30

Abstract

A method for processing and casting sand mould by laser and a laser processing device are provided, the device comprises a control system, a workbench, a laser generator and a scanning mirror, after raw sand and binder are mixed and made into sand blocks, the control system controls the scanning mirror to operate based on data information of the sand mould, laser is utilized to irradiate processing areas needing to be removed on the sand blocks, the binder in the processing areas is heated to lose efficacy, and molding sand scattered due to the failure of the binder is removed to form the required casting sand mould. The time for processing the casting mold is shorter, the cost is lower, the efficiency is higher, the step problem of the layering position of the additive manufacturing sand mold such as 3D printing can be effectively avoided, the processing precision of the casting mold is higher, and the subsequent finishing work is reduced. The used molding sand can be common molding sand, can be selected and adjusted according to casting materials and process parameters, ensures that the casting sand mold is the same as the casting process parameters, can improve the finished product rate of castings, and reduces the production cost.

Description

Method for casting sand mold by laser processing and laser processing device

Technical Field

The invention relates to a casting mold processing technology, in particular to a method for processing a casting sand mold by laser and a laser processing device.

Background

The traditional casting technology is that a casting mold for casting is manufactured by utilizing a mold, liquid metal is poured into the casting mold, and a metal part is obtained after solidification.

With the development of intelligent manufacturing technology, revolutionary changes are brought to casting technology, and various methods for manufacturing casting molds without using molds, such as 3D printing casting molds, digital milling casting molds and the like, appear. The digital milling processing speed is slow, the efficiency is low, a scheme of milling processing after the molding sand is frozen is proposed, and the prior art is immature and difficult to be practically applied.

The 3D printing casting mold adopts an additive manufacturing method of laying the molding sand materials layer by layer and connecting and solidifying the molding sand materials. The method can form steps between the sand layers, and the manufactured casting mold has uneven surface, lower precision and large subsequent processing amount. Moreover, the 3D printing mold requires special molding sand, and the mold material cannot be flexibly adjusted according to casting process parameters, which may result in a decrease in the yield of the casting.

The existing methods can be used for trial production or small-batch production of prototype parts, but still have the problems of long manufacturing time, high cost, low efficiency and the like.

Disclosure of Invention

The invention aims to provide a method for processing a casting sand mould by laser and a laser processing device, so as to improve the processing efficiency and quality of a casting mould.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for processing casting sand mould by laser includes such steps as mixing raw sand with adhesive to obtain sand block, laser irradiating the area to be removed on the sand block to make the adhesive in the area to be processed become invalid, and removing the sand mould.

And mixing the raw sand with a binder, and hardening to obtain the sand block.

The hardening process is to stand for 3 to 4 hours under natural conditions or to dry for 1.5 to 2.5 hours at the temperature of 110 ℃.

The binder is one or more of synthetic resin, tung oil or starch which can lose or reduce the binding performance by heating.

And further, measuring the three-dimensional data of the sand block to obtain a current three-dimensional data model, and comparing the current three-dimensional data model with the required casting sand mold three-dimensional data model to determine a processing area required to be removed.

And further, controlling a laser beam to carry out laser scanning on a processing area needing to be removed on the sand block, and after the collapsed molding sand is removed, repeating the three-dimensional data measurement and the laser scanning operation until the current three-dimensional data model is matched with the required casting sand mold three-dimensional data model.

The invention also provides a laser processing device which comprises a control system, a workbench, a laser generator and a scanning mirror, wherein the control system controls the scanning mirror to operate based on the sand mold data information, and the scanning mirror is used for controlling the laser beam emitted by the laser generator to scan and irradiate the area to be processed of the sand block on the workbench, so that the binder in the processing area is heated and loses efficacy, and the material reduction processing is realized.

Furthermore, a 3D measuring device for measuring three-dimensional data of the sand block is further arranged, and the 3D measuring device is arranged on the workbench through the three-axis moving mechanism and is connected with the control system.

Further, a sand blowing device for removing the sand collapsing due to the binder failure is also provided.

The sand block clamping device is characterized in that a clamping mechanism used for positioning and fixing the sand block is arranged on the workbench, the clamping mechanism comprises a positioning element and a clamping device, the positioning element is of an L-shaped structure which is horizontally arranged, and the clamping device is opposite to the L-shaped long edge of the positioning element so as to clamp the sand block.

The invention has the beneficial effects that: because the moving speed of the laser beam greatly exceeds the speed of the printing nozzle when the 3D printing sand mold is printed, the processing speed of the invention exceeds the 3D printing sand mold in terms of a dieless casting method, the processing efficiency is greatly improved, and the processing time is shortened. In addition, as additive manufacturing methods such as 3D printing sand mould layering sanding and the like are not adopted, the step problem at the sand mould layering position can be effectively avoided, the casting mould processing precision is higher, and the subsequent finishing work is reduced. In addition, the molding sand used by the method can be common molding sand, can be selected and adjusted according to casting materials and process parameters, ensures that the casting sand mold is the same as the casting process parameters, can improve the yield of castings, and reduces the production cost.

On the basis, the sand block is scanned and processed in a laser scanning mode, and compared with a 3D printing casting mold and a digital milling casting mold in the prior art, the method has the advantages of shorter casting mold processing time, lower cost and higher efficiency, and is more suitable for mass production.

The laser processing device of the invention adopts the scanning mirror to control the laser beam path emitted by the laser generator, so that the laser generator can be fixedly installed, and the danger can be avoided when a laser generator with higher power is used. The device need not to adjust laser beam route by a wide margin, only need to scan the mirror carry out programming control can, convenient safety.

Drawings

FIG. 1 is a schematic diagram of the method of the present invention for laser machining a foundry sand mold.

Fig. 2 is a schematic structural view of the laser processing apparatus of the present invention.

The labels in the figure are: 1. a control system; 2. a work table; 3. a clamping mechanism; 301. a positioning element; 302. a clamping device; 4. a gantry; 5. an X-axis slide rail pair; 6. a Y-axis slide rail pair; 7. a Z-axis slide rail pair; 8. a 3D measurement device; 9. a laser generator; 10. a scanning mirror; 11. a sand blowing device; 12. and an air supply device.

Detailed Description

The technical scheme of the invention is clearly and completely explained in the following by combining the attached drawings and the detailed description. The specific contents listed in the following examples are not limited to the technical features necessary for solving the technical problems described in the claims. Meanwhile, the list is that the embodiment is only a part of the present invention, and not all embodiments.

The processing method adopted by the invention is essentially material reduction processing, raw sand and a binder are mixed to prepare a sand block according to the size of a required casting mould, then the part of the sand block which needs to be removed is irradiated by laser, and the temperature of the part is raised by utilizing the energy of the laser. The binder used for making the sand block is selected from binders which can be failed at high temperature, such as furan resin which can be decomposed at high temperature. In the processing area irradiated by laser, the binder mixed in the sand block is heated to lose efficacy, so that the molding sand is collapsed due to the reduction of the binding effect, and the laser processing is continued after the collapsed molding sand is removed until the required casting sand mold is obtained.

FIG. 1 is a flow chart of one embodiment of the process of the present invention. The processing steps comprise:

a. establishing a three-dimensional data model of a casting;

b. establishing a casting three-dimensional data model according to the casting three-dimensional data model;

c. manufacturing a sand block according to the size of the casting mold;

d. three-dimensional measurement is carried out to obtain sand block point cloud data;

e. comparing the point cloud data with the casting three-dimensional data model, and obtaining a region to be processed;

f. according to the comparison result in the step e, laser scanning and processing;

g. cleaning loose sand; according to the requirement, loose sand can be cleaned in a blowing or air suction mode;

h. and d, repeating the steps d-g until a required casting mold is obtained, wherein the structure of the required casting mold is matched with the three-dimensional data model of the casting mold.

And b, sequentially establishing the required data models through modeling software, or directly establishing the three-dimensional data model of the casting mold to be processed through the modeling software.

In the step c, the raw sand used for preparing the sand block is selected according to the requirement of the casting process, and one or more of quartz sand, magnesia, zircon sand, olivine sand, chromite sand, corundum sand, ceramsite sand or jewel sand can be selected.

The raw sand and the binder are fully mixed to prepare a sand block, and the shape of the sand block is determined according to the requirement. The sand block can be manufactured by using simple moulds, such as a square box. And stirring and mixing the raw sand and the binder to form loose molding sand, filling the loose molding sand into a square frame with a required size, and performing an over-hardening process to obtain a hardened sand block. The required hardening process is determined according to the selected binder, for example, standing for 3-4 hours under natural conditions or drying for 1.5-2.5 hours at 110 ℃.

The binder can be one or more of synthetic resin, tung oil or starch, or other similar binders which can lose or reduce the binding performance under heat.

For example, adding a certain amount of quartz sand with the particle size distribution of 50/100 meshes into a sand mixer, simultaneously adding liquid furan resin accounting for 1.2 percent of the weight of the quartz sand, mixing for 1 minute, then adding a benzenesulfonic acid curing agent, wherein the adding amount of the curing agent is 40 percent of the weight of the furan resin, mixing for 1 minute, discharging sand from the sand mixer, filling the mixed self-hardening resin sand into a prepared frame, automatically hardening the molding sand after a period of time, and removing the frame to obtain a solidified sand block; the sand block has the advantages of high strength and good manufacturability.

For example, a certain amount of chromite sand with 70/140 meshes of particle size distribution is added into a sand mixer, 3 percent of alpha starch accounting for the weight of the sand is added at the same time, after the alpha starch is uniformly mixed, 3 percent of water accounting for the weight of the sand is added for mixing and rolling for 3 minutes, then the mixed molding sand is filled into a prepared square frame, the molding sand and the square frame are put into a drying furnace together, the drying is carried out for 2 hours at the temperature of 110 ℃, after the drying furnace is taken out and cooled, the square frame is removed, and then a solidified sand block can be obtained.

In actual production, a plurality of sand blocks can be manufactured at one time for standby.

In the steps d and e, before the laser processing of the sand block, the three-dimensional point cloud data of the sand block can be measured by using the measuring device, a current three-dimensional data model of the sand block is constructed, the current three-dimensional data model of the sand block is compared with a previously established casting sand mould three-dimensional data model, a difference value between the current three-dimensional data model and the previously established casting sand mould three-dimensional data model is obtained, and then the curved surface data of the processing area needing to be removed is determined and is transmitted to the control system to be used as a basis for controlling the laser processing.

And f, controlling the laser to process the processing area of the sand block according to the processing data obtained by comparison. The laser processing can adopt a scanning mode, and the laser beam is controlled to carry out laser scanning on a processing area needing to be removed on the sand block, so that the sand mold binder in a scanning range is heated to lose efficacy. For example, a sand block prepared by mixing quartz sand, furan resin and benzenesulfonic acid curing agent is adopted, the laser scanning is carried out on the area to be processed to raise the temperature of the area, and when the temperature of the area scanned by the laser exceeds 300 ℃, the furan resin starts to decompose, so that the molding sand in the area is completely dispersed.

And g, when the processing surface of the sand block faces upwards, blowing away the loose sand by means of air blowing or sucking out the loose sand by means of air suction. If the side surface of the sand block is processed or the bottom surface of the sand block is processed by suspending the sand block, the sand block can naturally fall and be removed by using the dead weight of the loose sand.

Step h is a repeat of steps d-g above. And after the scattered molding sand is removed, measuring the three-dimensional point cloud data of the sand block again through a measuring device, if the current three-dimensional data of the sand block meets the requirement of the required three-dimensional data of the casting sand mold, continuing to use laser processing, and repeating the steps until the current three-dimensional data model is matched with the required three-dimensional data model of the casting sand mold.

In the process, the three-dimensional data of the sand block is measured, the laser processing and the sand scattering removal are not required to be carried out until the previous operation is completely finished, for example, while the laser scanning processing is carried out, the sand cleaning operation can be started in the scanned area, and the measurement can be carried out in the sand cleaned area.

Fig. 2 is a schematic view showing an embodiment of the laser processing apparatus of the present invention. The processing device comprises a control system 1, a workbench 2, a laser generator 9 and a scanning mirror 10. The table 2 is used for placing sand blocks and installing related components. The scanning mirror 10 is used for controlling the laser beam emitted by the laser generator 9 to scan and process the sand block.

The worktable 2 is provided with a clamping mechanism 3 which can position and fix the sand block on the surface of the worktable 2. For example, the clamping mechanism comprises a positioning element 301 and a clamping device 302. The positioning elements 301 and the clamping devices 302 are arranged at intervals along the width direction of the workbench 2 and are matched with each other to clamp and fix the sand block. The positioning element is in a horizontally arranged L-shaped structure, and the inner side surfaces of the long sides of the positioning element 301 are opposite to the clamping surfaces of the clamping device 302. The clamping device 302 may be a horizontally arranged telescopic device, such as a pneumatic cylinder, an electric telescopic rod, etc. The clamping device is opposite to the long L-shaped edge of the positioning element so as to clamp the sand block.

A portal frame 4 is arranged in the middle of the table top of the workbench 2, an X-axis slide rail pair 5 is arranged on the top surface of the portal frame 4 along the axial direction of the portal frame, a Y-axis slide rail pair 6 is arranged at the sliding end of the X-axis slide rail pair 5, a Z-axis slide rail pair 7 is arranged at the sliding end of the Y-axis slide rail pair 6, a 3D measuring device 8 capable of measuring the shape of the sand block is arranged at the sliding end of the Z-axis slide rail pair 7, and an imaging element and a light-emitting element are arranged in the 3D measuring device. The X-axis slide rail pair 5, the Y-axis slide rail pair 6 and the Z-axis slide rail pair 7 form a three-axis moving mechanism, so that the 3D measuring device 8 can move in all directions, and the sand block can be comprehensively measured.

The slide rail pair can be a motor and a transmission device, and the transmission device can comprise a slide rail, a slide block in sliding fit with the slide rail, a lead screw in transmission fit with the slide block and a motor output shaft or a structure with similar functions according to needs.

The inner top surface of the gantry 4 is provided with a laser generator 9 and a scanning mirror 10 at intervals along the axial direction. The 3D measuring device 8 is connected to the control system 1, and the control system 1 controls the operation of the scanning mirror 10 according to the measurement result and the compared processing data.

In an embodiment not shown in the drawings, the scanning mirror 10 includes a scanning mirror body and an adjusting device for adjusting the angle of the scanning mirror body, and the adjusting device may be a mechanical arm, an angle adjuster, or the like, which can adjust the angle of the scanning mirror 10 and change the path of the laser beam emitted by the laser generator 9. During specific machining, laser beams emitted by the laser generator 9 irradiate the scanning mirror 10, the scanning mirror 10 enables the laser beams to be reflected to a machining area of the sand block, the binder of the machining area is heated to be invalid, and material reduction machining is carried out on the machining area of the sand block.

The invention adopts the arrangement of the scanning mirror 10, so that the laser generator 9 can be fixedly arranged and is always relatively fixed with the worktable 2, thereby having the following advantages: a. a higher power laser generator 9 can be used and danger can be avoided; b. the position of the laser generator 9 does not need to be adjusted, so that the laser generator 9 can stably output, and only the scanning mirror 10 needs to be programmed and controlled, thereby being convenient and safe

In this embodiment, the sand blower 11 is used to remove the scattered sand from the sand pool. The sand blowing device 11 is arranged on the table top of the workbench 1 and is connected with an air supply device 12 for providing air flow. The gas supply 12 may be an air compressor or a tank with pressurized gas in the inner chamber. The sand blowing device 11 comprises a flexible air pipe, one end of the flexible air pipe is correspondingly communicated with the air outlet of the air supply device 12, the air blowing position and angle can be adjusted according to needs, and an air blowing nozzle is arranged at the other end of the flexible air pipe. An electromagnetic valve is arranged between the flexible air pipe and the air outlet of the air supply device 12 according to requirements.

As shown in fig. 2, two sand blowing devices 11 are provided, and the two sand blowing devices 11 are respectively correspondingly arranged at two sides of the positioning element 301. If desired, the sand-blasting device 11 may be located on the side of the positioning element 301 facing away from the clamping device 302.

By utilizing the method and the device, the moving speed of the laser beam greatly exceeds the speed of the printing nozzle during 3D printing of the sand mold, so that the processing speed of the dieless casting method exceeds that of the 3D printing of the sand mold, the processing efficiency is greatly improved, and the processing time is shortened; because no additive manufacturing method of layering and sanding of a 3D printing sand mold is adopted, the problem of layering steps of the sand mold is effectively solved, and the processing precision can be improved; in addition, the used molding sand is common molding sand, and has the same parameters as the current casting process, thereby improving the finished product rate of castings and reducing the production cost.

The above description of the specific embodiments is only for the purpose of helping understanding the technical idea of the present invention and the core idea thereof, and although the technical solution is described and illustrated herein using the specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and detail may be made therein by those skilled in the art without departing from the technical spirit of the present invention. Such modifications and substitutions are intended to be included within the scope of the present invention.

Claims

1. A method for processing and casting sand mould by laser is characterized in that: mixing raw sand and a binder and preparing the mixture into a sand block, irradiating a processing area needing to be removed on the sand block by using laser to ensure that the binder in the processing area is heated to lose efficacy, and removing the molding sand collapsed due to the failure of the binder to form the required casting sand mold.

2. A method of laser machining a casting sand mold according to claim 1, wherein: the binder is one or more of synthetic resin, tung oil or starch which can lose or reduce the binding performance by heating.

3. A method of laser machining a casting sand mold according to claim 1, wherein: and measuring the three-dimensional data of the sand block to obtain a current three-dimensional data model, and comparing the current three-dimensional data model with the required casting sand mold three-dimensional data model to determine a processing area required to be removed.

4. A method of laser machining a casting sand mold according to claim 3, wherein: and controlling a laser beam to carry out laser scanning on a processing area needing to be removed on the sand block, and after the scattered molding sand is removed, repeating the three-dimensional data measurement and the laser scanning operation until the current three-dimensional data model is matched with the required casting sand mold three-dimensional data model.

5. A method of laser machining a casting sand mold according to claim 1, wherein: and mixing the raw sand with a binder, and hardening to obtain the sand block.

6. A method of laser machining a casting sand mould according to claim 5, wherein: the hardening process is to stand for 3 to 4 hours under natural conditions or to dry for 1.5 to 2.5 hours at the temperature of 110 ℃.

7. A laser processing apparatus for use in the method of laser processing a casting sand mold according to claims 1 to 6, characterized in that: including control system (1), workstation (2), laser generator (9) and scanning mirror (10), control system (1) based on sand mould data information control scanning mirror (10) function, scanning mirror (10) are used for controlling the laser beam of laser generator (9) transmission and scan the district to be processed of sand block on the workstation and shine, make the regional binder of processing be heated inefficacy to realize subtracting material processing.

8. The laser processing apparatus according to claim 7, wherein: and a 3D measuring device (8) for measuring three-dimensional data of the sand block is further arranged, and the 3D measuring device is arranged on the workbench (2) through a three-axis moving mechanism and is connected with the control system (1).

9. The laser processing apparatus according to claim 7, wherein: a sand blowing device (11) for removing sand collapsing due to binder failure is also provided.

10. The laser processing apparatus according to claim 7, wherein: the sand block clamping device is characterized in that a clamping mechanism (3) used for positioning and fixing a sand block is arranged on the workbench, the clamping mechanism comprises a positioning element (301) and a clamping device (302), the positioning element is of an L-shaped structure horizontally arranged, and the clamping device is opposite to the L-shaped long edge of the positioning element so as to clamp the sand block.