Metal powder metallurgy heat treatment jig

Abstract

The utility model discloses a kind of metal powder metallurgy heat treatment fixtures, the utility model makes the deformation amount control in the range of design requirement in the heat treatment process of product by the specific size of upper and lower cover plate and base in combination with the deformation of product, product can also be guaranteed in heat treatment process not to be interfered by external force to indirectly eliminate the heat treatment stress of product, to reduce product cracking risk. Different cooling water tank is set up on jig simultaneously, product performance uneven situation caused by product each part cooling uneven in heat treatment process is also effectively avoided, and deformation and cracking risk of product also avoid. The heat treatment fixture structure disclosed in the utility model is simple, and it plays the role of fixing and correcting shaping for the heat treatment piece of MIM piece and machining piece of abnormal complex structure.

Description

Technical Field

[0001] This utility model relates to the field of metal powder metallurgy technology, and more specifically, to a metal powder metallurgy heat treatment fixture. Background Technology

[0002] MIM (Metal Injection Molding) is a high-tech process that mixes metal powder with an organic binder and then uses plastic injection molding to create near-net-shape metal parts. It combines the material property advantages of powder metallurgy with the high precision and complex shape forming capabilities of plastic injection molding, making it the mainstream technology for manufacturing small, precision metal parts.

[0003] However, in the MIM (Metal Injection Molding) production process, more complex products are more prone to deformation, including sintering deformation and heat treatment deformation. Among these, heat treatment deformation is the most difficult to manage. Reasons for this include: fluctuations in the binder system, powder and binder segregation, improper temperature and heating rate, inadequate cooling methods, carbon content, part structural complexity, lack of preheating and staged cooling, etc. Heat treatment is generally the final step in the product manufacturing process, and the deformation that occurs during heat treatment is the most critical, as it cannot be improved by subsequent actions and directly affects the product's performance and production yield. Utility Model Content

[0004] This invention overcomes the shortcomings of existing technologies in heat treatment steps and provides a metal powder metallurgy heat treatment fixture, which is expected to solve the above-mentioned problems.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A metal powder metallurgy heat treatment fixture includes a fixture base and a fixing clamp.

[0007] The fixture base is provided with a fixing clip, and the heat-treated product is installed on the fixture base through the fixing clip;

[0008] The fixture base is provided with a compensation surface. During the heat treatment process, the product is fixed to the fixture base by a fixing clip, and the compensation surface compensates for the deformation of the product during heat treatment.

[0009] By fixing the MIM part with a clamp during the heat treatment process, the stress deformation caused by rapid cooling during the heat treatment process can be improved, and the product accuracy of heat treatment and shaping can be improved. After testing, it has been confirmed that by using this process, the deformation amount in the deformation direction can be controlled within 0.05mm on the fixture.

[0010] A further technical solution is that the fixture base is provided with cooling water channels, which are evenly distributed on the fixture base.

[0011] A further technical solution is that the cooling water path includes a cooling water tank disposed on the compensation surface, wherein the cooling water tank forms a protruding surface and a water tank surface on the compensation surface;

[0012] The fixing clips are located on both sides of the compensation surface, and the two ends of the product are fixed to the fixing clips on both sides of the compensation surface.

[0013] A further technical solution is that the fixing clip includes a columnar clip and / or an insertion clip.

[0014] A further technical solution is that the metal powder metallurgy heat treatment fixture also includes a fixture mold;

[0015] The fixture mold and fixture base are assembled and fixed by fasteners;

[0016] After installation and fixing, the jig mold closing surface mates with the jig base compensation surface, and there is a gap between the jig mold closing surface and the jig base compensation surface, the cross-sectional shape of the gap matching the product shape.

[0017] Although the product is already secured by clamps, by adding a jig and using the jig and base to compensate for the product shape, the product shape can be defined from both the front and back, resulting in a better compensation and shaping effect.

[0018] A further technical solution is that the fixing element is a screw;

[0019] The fixture mold is provided with a fixing screw hole that penetrates the fixture mold, and the fixture base is provided with a base screw hole at the position where it mates with the fixing screw hole.

[0020] A further technical solution is that the jig is provided with water passage holes on the mold closing surface;

[0021] The water passage includes an inlet and an outlet, which are evenly arranged on the mold assembly.

[0022] A further technical solution is that the fixture base is provided with a water passage connection channel;

[0023] The fixture base is provided with cooling water channels, and the water channel connecting channels connect the cooling water channels.

[0024] The position of the upper hole of the water passage corresponds to the position of the water inlet hole, and the position of the lower hole of the water passage corresponds to the position of the water outlet hole.

[0025] A further technical solution is that the fixture mold assembly includes a left fixture mold assembly and a right fixture mold assembly;

[0026] The fixture base is provided with a compensation surface and a fixing clip on its symmetrical sides;

[0027] The surfaces of the left and right molds of the fixture mate with the compensation surfaces on the left and right sides of the fixture base, respectively.

[0028] A further technical solution is that an extraction gap is provided between the left mold and the right mold of the fixture;

[0029] The fixture base is provided with a fixture removal groove at the clearance fit position between it and the removal position.

[0030] Compared with existing technologies, this utility model has at least the following beneficial effects: The heat treatment fixture disclosed in this utility model has a simple structure and plays a role in fixing and correcting the shape of heat-treated MIM parts and machined parts with abnormally complex structures. In practical applications, products with irregular thin-walled structures are installed on the fixture base by fixing clips, which plays a corrective and fixing role in the heat treatment process of products with irregular thin-walled structures. By combining the specific dimensions of the fixture base and the fixture mold with the deformation of the product, the deformation of the product during the heat treatment process is controlled within the design requirements. It also ensures that the product is not interfered with by external forces during the heat treatment process, thereby indirectly eliminating the heat treatment stress of the product and reducing the risk of product cracking. At the same time, different cooling water tanks are opened on the fixture, which also effectively avoids uneven product performance caused by uneven cooling of different parts of the product during the heat treatment process, and also avoids the risk of product deformation and cracking. The fixture has been tested and can significantly improve the first-pass yield of the product and effectively reduce the risk of product cracking, achieving the goal of cost reduction and efficiency improvement, and effectively solving the problem of heat treatment deformation of MIM and machined thin-walled products. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall installation structure of this utility model;

[0032] Figure 2 A schematic diagram of the product structure for installation;

[0033] Figure 3 This is a schematic diagram of the upper left cover structure of the fixture;

[0034] Figure 4 This is a schematic diagram of the upper right cover structure of the fixture;

[0035] Figure 5 This is a schematic diagram of the structure of a heat-treated product.

[0036] In the figure, 1- jig base, 11- first cooling water tank, 12- second cooling water tank, 13- third cooling water tank, 14- first protruding arc surface, 15- second protruding arc surface, 16- third protruding arc surface, 2- jig mold closing, 21- jig left mold closing, 22- jig right mold closing, 23- jig removal slot, 24- fixing screw, 25- water passage hole, 3- fixing clip, 31- columnar buckle, 41- ring buckle, 42- insertion buckle. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0038] A metal powder metallurgy heat treatment fixture includes a fixture base 1 and a fixing clip 3.

[0039] The fixture base 1 is provided with a fixing clip 3, and the heat-treated product is installed on the fixture base 1 through the fixing clip 3;

[0040] The fixture base 1 is provided with a compensation surface. During the heat treatment process, the product is fixed to the fixture base 1 by the fixing clip 3. The compensation surface compensates for the deformation of the product during the heat treatment.

[0041] It is understandable that the function of the compensation surface is to limit the deformation of the product during heat treatment, thereby compensating for the deformation. In this embodiment, the product shape reference... Figure 5 The cross-sectional shape of the middle part is an easily deformable arc surface. Therefore, the compensation surface is an arc surface that matches the bending shape of the product. This arc surface can limit the deformation of the middle part of the product during heat treatment.

[0042] In a preferred embodiment, the fixture base 1 is provided with cooling water channels, which are evenly distributed on the fixture base 1.

[0043] It should be noted that the cooling water channels can be embedded inside the fixture base 1 or grooved on the surface of the fixture. During the fixture design phase, it is necessary to ensure that the product is cooled uniformly during the cooling process. Therefore, more and more uniform cooling channels are required, such as horizontal and vertical cooling grooves, to prevent the following problems:

[0044] 1. Thermal stress caused by temperature gradient leads to deformation;

[0045] 2. Excessive cooling rate exacerbates deformation caused by stress concentration;

[0046] 3. The occurrence of problems such as volume changes and non-synchronicity of phase transitions.

[0047] In this embodiment, the cooling water path includes cooling water tanks disposed on the compensation surface. The shape and number of cooling water tanks are symmetrical from left to right, and there are 4 cooling water tanks on one side, namely the first cooling water tank 11, the second cooling water tank 12, the third cooling water tank 13, and the fourth cooling water tank.

[0048] The cooling water tank opening is located on the compensation surface, forming a protruding surface and a water tank surface on the compensation surface;

[0049] In this embodiment, four protruding arc surfaces are cut out from the above four cooling water tanks, namely the first protruding arc surface 14, the second protruding arc surface 15, the third protruding arc surface 16, and the fourth protruding arc surface;

[0050] It should be noted that, generally speaking, the width of the cooling water tank should not exceed 8mm, and the depth should be as deep as possible without affecting the strength of the fixture.

[0051] The protruding arc surface is used in conjunction with the actual arc surface of the product and the amount of product deformation to achieve the effect of the above-mentioned compensation surface. The specific amount of product compensation depends on the actual deformation of the product. In this embodiment, the compensation amount is between 0.05mm and 1mm.

[0052] The fixing clips 3 are disposed on both sides of the compensation surface. The two ends of the product are fixed to the fixing clips 3 on both sides of the compensation surface, and the middle part of the product is limited by the protruding surface.

[0053] The fixing clip 3 includes a columnar clip 31 and / or an insertion clip.

[0054] In this embodiment, the fixing clips 3 are disposed on the upper and lower sides of the compensation surface, with a columnar buckle 31 on the upper side of the compensation surface and an insertion buckle on the lower side of the compensation surface.

[0055] It is understood that the above settings are adapted to the structure of the product. In this embodiment, the upper part of the product is provided with a ring-shaped buckle 41, and the ring-shaped buckle has 4 snap fasteners inside, which can be securely fastened to the columnar snap fastener 31. The lower part of the product is designed with 3 insertion buckles 42, see [link to documentation]. Figure 5 .

[0056] It should be noted that during production and use, fixing the product to the fixture base with the fixing clips can enable the product to achieve heat exchange and shape compensation during heat treatment by adhering to the surface of the fixture. In other words, the technical effect of this application can still be achieved even without using a fixture for mold closing.

[0057] In a preferred embodiment, the metal powder metallurgy heat treatment fixture further includes a fixture mold 2.

[0058] The jig mold 2 and the jig base 1 are assembled and fixed by fasteners;

[0059] After installation and fixing, the jig mold 2 and the jig base 1 compensation surface are engaged, and there is a gap between the jig mold 2 and the jig base 1 compensation surface, and the cross-sectional shape of the gap matches the product shape.

[0060] In this embodiment, the fastener is a screw;

[0061] The fixture mold 2 is provided with a fixing screw hole that penetrates the fixture mold 2, and the fixture base 1 is provided with a base screw hole at the position where it mates with the fixing screw hole.

[0062] The main function of the jig mold 2 is to further define the position of the product heat treatment process and to cooperate with the jig base 1 for cooling.

[0063] In order to achieve better cooling effect, in a preferred embodiment, the jig mold 2 is provided with water passage holes 25;

[0064] The water passage 25 includes a water inlet and a water outlet, which are evenly arranged on the jig mold 2.

[0065] In this embodiment, the diameter of the water passage holes 25 is maintained at 4-6 mm and is evenly distributed on the jig mold 2. For example, the upper part of the jig mold 2 has a water inlet hole and the lower part has a water outlet hole. The water passage holes 25 are kept at equal distance from the product, thereby achieving uniform cooling.

[0066] In a preferred embodiment, a water passage is provided on the fixture base;

[0067] The fixture base is provided with cooling water channels, and the water channel connecting channels connect the cooling water channels.

[0068] It should be noted that the function of the water passage connection channel is to introduce external cooling water into the cooling water passage. In this embodiment, the cooling water passage on one side consists of four cooling water tanks. The water passage connection channel is buried in the fixture base 1 and connects the four cooling water tanks.

[0069] In a preferred embodiment, the position of the upper hole of the water passage corresponds to the position of the water inlet hole, and the position of the lower hole of the water passage corresponds to the position of the water outlet hole.

[0070] In actual use, water enters directly into the water passage through the inlet hole and flows sequentially from the water passage to the first cooling water tank 11, the second cooling water tank 12, the third cooling water tank 13, and the fourth cooling water tank, and finally flows out through the outlet hole.

[0071] In a preferred embodiment, the jig mold 2 includes a left jig mold 21 and a right jig mold 22;

[0072] The fixture base 1 is provided with a compensation surface and a fixing clip 3 on its symmetrical sides;

[0073] The surfaces of the left mold 21 and the right mold 22 of the fixture respectively mate with the compensation surfaces on the left and right sides of the fixture base 1.

[0074] A take-out gap is provided between the left mold 21 and the right mold 22 of the fixture;

[0075] The fixture base 1 is provided with a fixture removal groove 23 at the clearance fit position between it and the removal position.

[0076] In this embodiment, the width of the jig removal slot 23 should ensure that the product has sufficient clearance, and should not be too large to cause product deformation. The size should be set at 10mm-12mm, and the height should be as deep as possible without affecting the strength.

[0077] By setting the left mold 21 and the right mold 22 of the fixture, a gap can be set between the molds to facilitate the installation and removal of the product.

[0078] The heat treatment fixture described in this patent has a simple structure and can fix and correct the shape of heat-treated MIM parts and machined parts with exceptionally complex structures. In the embodiment, the arc shape of the fixture base is determined by the shape of the product. Using this method to heat-treat and shape MIM products and machined products (including but not limited to shape memory alloys) can improve the stress deformation caused by rapid cooling during heat treatment.

[0079] Testing showed that, using the process described in this application, the deformation in the deformation direction can be controlled within 0.05 mm. For example, the fixture can be made of steel with better hardenability, such as CrWMn / 1.2767 /

[0080] GS-436 / X50CrMoW9-1-1 / CM8 / SKD11 etc.;

[0081] Currently, the heat treatment methods used for existing MIM parts in non-liquid heat treatment are basically no different from those used for other parts. They are generally laid flat or stacked in the working area of ​​the heat treatment equipment. The deformation of the product is completely free. The product is prone to deformation during heat treatment and needs to be corrected by mechanical or other machining methods in the later stage.

[0082] For some products with high requirements, ornaments are fixed to refractory bricks with specific structures for auxiliary control, heat treatment and cooling treatment. However, this method is difficult to achieve mass production and has limited precision. In the later stage, it is still necessary to correct the deformation of the product material through shaping or other methods.

[0083] Currently, liquid heat treatment mainly uses unrestricted frame stacking for cooling, and product deformation is completely uncontrolled. Deformation correction is mainly achieved through shaping and machining before and after heat treatment.

[0084] In summary, regardless of the heat treatment method used, the product requires two shaping processes, one before and one after heat treatment. These processes are complex, resulting in high processing costs. Furthermore, the shaping process after heat treatment carries an increased risk of breakage.

[0085] This application discloses a fixture for fixing and correcting products during heat treatment. Therefore, this concept was proposed and related verification and testing were conducted. Figure 5 Taking the product shown as an example, the yield rate of the product after ordinary heat treatment and quenching is 0. It mainly relies on the subsequent correction of the product contour by hydraulic press and the CNC machining refinement of the hook position dimensions. The product has high processing cost, long production cycle and low yield.

[0086] The aforementioned products, after being fixed in the aforementioned fixture and then subjected to heat treatment, achieve a yield rate of over 95%. Furthermore, the previous CNC machining process is directly eliminated, achieving cost reduction and efficiency improvement. Simultaneously, this solution was validated by applying vacuum heat treatment to some MIM parts. The yield rate after a single heat treatment was verified to be over 80%, far exceeding the yield rate of the original process. Moreover, the fixture is easily replicated and readily mass-produced, enabling automated product clamping and improving product turnover efficiency.

[0087] Although the present invention has been described herein with reference to illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and improvements can be made to the components and / or layout of the subject matter combination within the scope of the present application. Besides variations and improvements to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A heat treatment fixture for metal powder metallurgy, characterized in that, Includes a fixture base and a fixing clip; The fixture base is provided with a fixing clip, and the heat-treated product is installed on the fixture base through the fixing clip; The fixture base is provided with a compensation surface. During the heat treatment process, the product is fixed to the fixture base by a fixing clip, and the compensation surface compensates for the deformation of the product during heat treatment.

2. The metal powder metallurgy heat treatment fixture as described in claim 1, characterized in that, The fixture base is provided with cooling water channels, which are evenly distributed on the fixture base.

3. The metal powder metallurgy heat treatment fixture as described in claim 2, characterized in that, The cooling water path includes a cooling water tank disposed on the compensation surface, wherein the cooling water tank forms a protruding surface and a water tank surface on the compensation surface; The fixing clips are located on both sides of the compensation surface, and the two ends of the product are fixed to the fixing clips on both sides of the compensation surface.

4. A metal powder metallurgy heat treatment fixture as described in claim 3, characterized in that, The fixing clip includes a columnar clip and / or an insert clip.

5. A metal powder metallurgy heat treatment fixture as described in any one of claims 1-4, characterized in that, It also includes jig fitting; The fixture mold and fixture base are assembled and fixed by fasteners; After installation and fixing, the jig mold closing surface mates with the jig base compensation surface, and there is a gap between the jig mold closing surface and the jig base compensation surface, the cross-sectional shape of the gap matching the product shape.

6. A metal powder metallurgy heat treatment fixture as described in claim 5, characterized in that, The fastener is a screw; The fixture mold is provided with a fixing screw hole that penetrates the fixture mold, and the fixture base is provided with a base screw hole at the position where it mates with the fixing screw hole.

7. A metal powder metallurgy heat treatment fixture as described in claim 5, characterized in that, The fixture is provided with a water passage hole; The water passage includes an inlet and an outlet, which are evenly arranged on the mold assembly.

8. A metal powder metallurgy heat treatment fixture as described in claim 7, characterized in that, The fixture base is provided with a water passageway; The fixture base is provided with cooling water channels, and the water channel connecting channels connect the cooling water channels. The position of the upper hole of the water passage corresponds to the position of the water inlet hole, and the position of the lower hole of the water passage corresponds to the position of the water outlet hole.

9. A metal powder metallurgy heat treatment fixture as described in claim 5, characterized in that, The clamping of the fixture includes clamping the left mold of the fixture and closing the mold of the right fixture; The fixture base is provided with a compensation surface and a fixing clip on its symmetrical sides; The surfaces of the left and right molds of the fixture mate with the compensation surfaces on the left and right sides of the fixture base, respectively.

10. A metal powder metallurgy heat treatment fixture as described in claim 9, characterized in that, A take-out gap is provided between the left mold and the right mold of the fixture; The fixture base is provided with a fixture removal groove at the clearance fit position between it and the removal position.

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