Die and method for controlling sintering deformation of hard alloy
By designing molds with multiple splicing plates and conical hole sections, applying pressure to constrain the cemented carbide workpieces, the sintering deformation problem is solved and the product pass rate is improved.
Patent Information
- Application Number
- CN202411370746.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2025-01-07
AI Technical Summary
During the sintering process, cemented carbide workpieces that are prone to deformity are prone to problems such as the outer frame and the inner holes of the outer circle, and the size is difficult to control, resulting in the product pass rate being less than 70%.
A mold including multiple splicing plates is designed. By forming an interference fit and pre-sintered workpiece set, the workpiece is applied to impose pressure to restrain the workpiece and reduce the probability of deformation by using gradually enlarged conical hole sections and conical-like molds.
It effectively reduces the probability of sintering deformation of cemented carbide, improves the product's pass rate, and ensures the dimensional regularity of the workpiece.
Smart Images
Figure CN119260001A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of cemented carbide preparation, and in particular to a mold and a method for controlling the sintering deformation of cemented carbide. Background Art
[0002] Small cemented carbide products shrink and are not easily deformed during the sintering process, and their product qualification rate is high. However, some easily deformed cemented carbide workpieces are prone to various sintering deformations, such as cemented carbide workpieces with high bonding phase (for example, bonding phase greater than 25wt%) and cemented carbide workpieces with high height dimensions (greater than 150mm). The above-mentioned easily deformed cemented carbide workpieces are prone to bulging in the lower and middle parts of the outer circle, enlarged inner holes, and difficult to control dimensions, resulting in a product qualification rate of less than 70%. Summary of the invention
[0003] The main purpose of the present invention is to provide a die and method for controlling the sintering deformation of cemented carbide, so as to solve the technical problem of low qualified rate of cemented carbide workpieces which are easy to deform.
[0004] To achieve the above object, the present invention provides a die for controlling the sintering deformation of cemented carbide, comprising:
[0005] The first mold includes a plurality of splicing plates, and the plurality of splicing plates can be respectively surrounded along the width direction of each splicing plate and spaced between two adjacent splicing plates to form a first structure. The first structure has a first space. The first space can form an interference fit with the pre-sintered workpiece, and the interference is 0.5 to 3.0 mm. The pre-sintered workpiece is a workpiece corresponding to the target workpiece, and the blank is sintered until the linear shrinkage rate reaches more than 95%.
[0006] The second mold has a through mounting hole, and the mounting hole includes a tapered hole section with a diameter gradually increasing from bottom to top. The second mold is sleeved on the first structure through the mounting hole, and the first structure is constrained by the tapered hole section to follow the changes of the pre-sintered workpiece and fit the pre-sintered workpiece.
[0007] According to an embodiment of the present application, the first structure is a cone-like structure that gradually shrinks from bottom to top. The cone hole section matches the cone-like structure.
[0008] According to an embodiment of the present application, the cone angles of the cone hole section and the cone-like cylinder structure are both 75° to 85°.
[0009] According to an embodiment of the present application, the mounting hole further comprises a cylindrical hole section coaxially arranged with the small end of the tapered hole section, and the diameter of the cylindrical hole section and the diameter of the small end of the tapered hole section are the same as the diameter of the small end of the cone-like cylinder.
[0010] According to an implementation manner of the present application, the number of the splicing plates is 3 to 4, and the splicing plates are identical.
[0011] According to an embodiment of the present application, the edges of the splicing plate in the width direction are non-linear edges.
[0012] The present application also provides a method for controlling the sintering deformation of cemented carbide, using the above-mentioned mold for controlling the sintering deformation of cemented carbide, the method for controlling the sintering deformation of cemented carbide includes:
[0013] The green body corresponding to the target workpiece is sintered until the linear shrinkage rate reaches more than 95% to obtain a pre-sintered workpiece.
[0014] The plurality of splicing plates of the first mold are respectively attached to the pre-sintered workpiece, surrounded along the width direction of each splicing plate and spaced between two adjacent splicing plates to form a first structure; the first structure forms an interference fit with the pre-sintered workpiece, and the interference is 0.5-3.0mm.
[0015] The second mold is sleeved on the first structure through the mounting hole, and sintering is continued until the pre-sintered workpiece is formed.
[0016] According to an embodiment of the present application, the step of sintering a green body corresponding to a target workpiece until a linear shrinkage rate reaches more than 95% to obtain a pre-sintered workpiece includes:
[0017] The green body is sintered at 1300° C. to 1350° C. until the linear shrinkage rate reaches 95%, thereby obtaining a pre-sintered workpiece.
[0018] According to an embodiment of the present application, in the step of continuing sintering until the pre-sintered workpiece is formed, the sintering temperature is 1350-1500° C., and the sintering time is 60-75 minutes.
[0019] According to an embodiment of the present application, the target workpiece satisfies at least one of the following conditions: height ≥ 150 mm, binder phase ≥ 25 wt%, and ring shape.
[0020] In the above-mentioned mold for controlling the sintering deformation of cemented carbide, the first structure formed by the multiple splicing plates is constrained by the tapered hole section in the second mold and is sleeved outside the pre-sintered workpiece. The first structure is interference fit with the pre-sintered workpiece, thereby applying pressure to constrain the pre-sintered workpiece. After the pre-sintered workpiece continues to sinter and shrink, the second mold moves downward under the action of its own gravity, compressing the gaps between the splicing plates to reduce, so that the multiple splicing plates shrink inward to follow the changes of the pre-sintered workpiece, always locking the outer surface of the pre-sintered workpiece, and reducing the probability of its deformation. The above-mentioned mold for controlling the sintering deformation of cemented carbide can effectively reduce the probability of sintering deformation of cemented carbide and improve the qualified rate of cemented carbide. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.
[0022] Figure 1 is a top view of a mold for controlling sintering deformation of cemented carbide according to an embodiment of the present application;
[0023] Figure 2 is a cross-sectional schematic diagram of a first mold according to an embodiment of the present application;
[0024] Figure 3 It is a cross-sectional schematic diagram of the second mold according to one embodiment of the present application.
[0025] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings.
[0026] Description of reference numerals:
[0027] 100, first mold; 200, second mold;
[0028] 110, splicing plate; 120, first space; 210, mounting hole; 211, tapered hole section; 212, cylindrical hole section. DETAILED DESCRIPTION
[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0030] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0031] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.
[0032] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.
[0033] To achieve the above object, the present invention provides a die for controlling the sintering deformation of cemented carbide. Figures 1 to 3 , including a first mold 100 and a second mold 200.
[0034] The mold for controlling the sintering deformation of cemented carbide is used for sintering workpieces. Therefore, the materials of the first mold 100 and the second mold 200 are high temperature resistant materials, such as graphite, silicon carbide, silicon nitride, molybdenum carbide, etc. The specific material types are not limited, and one or more of them can be selected. The materials of the first mold 100 and the second mold 200 can be the same, for example, both are made of graphite materials, or they can be made of different materials.
[0035] The first mold 100 includes a plurality of splicing plates 110. The plurality of splicing plates 110 can be respectively surrounded along the width direction of each splicing plate 110 and spaced between two adjacent splicing plates 110 to form a first structure. The first structure has a first space 120. The first space 120 can form an interference fit with the pre-sintered workpiece, and the interference is 0.5 to 3.0 mm. The pre-sintered workpiece is a workpiece corresponding to the target workpiece, and the blank is sintered to a linear shrinkage rate of more than 95%.
[0036] Each splicing board 110 is spliced along its width direction, and a certain interval is reserved in the width direction of two adjacent splicing boards 110 to form a first structure. In other words, the height of each part of the first structure is the height of the corresponding splicing board 110, and there is no situation in the first structure where two splicing boards 110 are completely spliced vertically along their own height direction.
[0037] There is no specific requirement for the number of the splicing plates 110, as long as they can be spliced to form the first structure according to the aforementioned splicing requirements. For example, the number of the splicing plates 110 is 2, 3, 4, 5, 6 or more.
[0038] Likewise, the shapes and sizes of the splicing plates 110 may be completely identical, partially identical, or completely different, and there are no specific requirements. As long as they can be spliced to form the first structure according to the aforementioned splicing requirements, it will be fine.
[0039] Likewise, the spacings between the splicing plates 110 in the width direction may be completely the same, partially the same, or completely different, and there is no specific requirement, as long as they can be spliced to form the first structure in accordance with the aforementioned splicing requirements.
[0040] The inner cavity of the first structure is the first space 120. The pre-sintered workpiece is a workpiece in which the green body corresponding to the target workpiece is sintered until the linear shrinkage rate reaches more than 95%. During the process of continuing to sinter the pre-sintered workpiece to the target workpiece, the linear shrinkage is relatively small and controllable. The size of the pre-sintered workpiece is slightly larger than the target workpiece.
[0041] The shape of the first space 120 corresponds to the shape of the outside of the pre-sintered workpiece. For example, if the pre-sintered workpiece is in the shape of a ring, the shape of the first space 120 is in the shape of a cylinder. If the pre-sintered workpiece is in the shape of a cuboid, the shape of the first space 120 is in the shape of a cuboid. The inner cavity size of the first structure is slightly smaller than the size of the pre-sintered workpiece, so that when the first structure is wrapped around the pre-sintered workpiece, an interference fit is formed. According to the above analysis, the linear shrinkage of the continued sintering of the pre-sintered workpiece is relatively small and controllable. Therefore, the subsequent adjustment space of the first space 120 is also correspondingly small, and the setting of the gap between any two adjacent splicing plates 110 and the interference between the first space 120 and the pre-sintered workpiece can meet the adjustment requirements.
[0042] The second mold 200 has a through mounting hole 210. The mounting hole 210 includes a tapered hole section 211 whose aperture gradually increases from bottom to top. The second mold 200 is sleeved on the first structure through the mounting hole 210, and the first structure is constrained by the tapered hole section 211 to follow the changes of the pre-sintered workpiece and fit the pre-sintered workpiece.
[0043] The second mold 200 is sleeved on the first structure through the mounting hole 210. The tapered hole section 211 gradually increases from bottom to top. When the first structure is sleeved outside the pre-sintered workpiece and sintering has not begun, the second mold 200 compresses and constrains the first structure through the tapered hole section 211 so that it compresses and locks the pre-sintered workpiece.
[0044] As sintering continues, the pre-sintered workpiece shrinks inward. Since there is a spacing between the splicing plates 110 of the first structure, there is an adjustment space for inward contraction. The spacing between the splicing plates 110 is reduced, and the corresponding first space 120 is reduced to continue to fit on the shrunk pre-sintered workpiece. The second mold 200 slides downward relative to the first structure using the adjustment function of the tapered hole section 211, and the tapered hole section 211, which is narrower than the initial position, contacts the first structure, continues to press the first structure to be in close contact with the shrunk pre-sintered workpiece, locks the outer surface of the pre-sintered workpiece, and reduces the probability of its deformation. In this process, the tapered hole section 211 constrains the first structure to follow the changes of the pre-sintered workpiece and fit the pre-sintered workpiece.
[0045] In the above-mentioned mold for controlling the sintering deformation of cemented carbide, the first structure formed by the multiple splicing plates 110 is constrained by the tapered hole section 211 in the second mold 200 and is sleeved outside the pre-sintered workpiece. The first structure is interference fit with the pre-sintered workpiece, thereby applying pressure to constrain the pre-sintered workpiece. After the pre-sintered workpiece continues to sinter and shrink, the second mold 200 moves downward under the action of its own gravity, compressing the gaps between the splicing plates 110 to reduce, so that the multiple splicing plates 110 shrink inward to follow the changes of the pre-sintered workpiece, always locking the outer surface of the pre-sintered workpiece, and reducing the probability of its deformation. The above-mentioned mold for controlling the sintering deformation of cemented carbide can effectively reduce the probability of sintering deformation of cemented carbide and improve the qualified rate of cemented carbide.
[0046] In some embodiments, reference Figures 2 to 3 The first structure is a cone-like structure that gradually shrinks from bottom to top. The cone hole section 211 matches the cone-like structure.
[0047] The contact area between the first structure and the second mold 200 is relatively large. The second mold 200 can provide uniform inward compression pressure to the first structure in both the circumferential and height directions, so that the first structure provides uniform pressure to the pre-sintered workpiece in both the circumferential and height directions, reducing the probability of sintering deformation of the workpiece as a whole.
[0048] In some embodiments, reference Figures 2 to 3 The cone angles of the cone hole section 211 and the cone-like cylinder structure are both 75° to 85°. Under this condition, it is easy for the second mold 200 to be inserted into the first structure, and the sliding is also relatively smooth.
[0049] In some embodiments, reference Figures 2 to 3 The mounting hole 210 further includes a cylindrical hole section 212 coaxially arranged with the small end of the tapered hole section 211. The diameter of the cylindrical hole section 212 and the diameter of the small end of the tapered hole section 211 are the same as the diameter of the small end of the cone-like cylinder.
[0050] The cylindrical hole section 212 increases the deadweight of the second mold 200 , especially the weight of the upper portion of the second mold 200 . Therefore, the pressure of the first mold 100 on the pre-sintered workpiece is increased, further reducing the probability of sintering deformation of the entire workpiece.
[0051] In some embodiments, reference Figures 1 to 3 The number of the splicing plates 110 is 3 to 4, and each of the splicing plates 110 is the same.
[0052] This method has an appropriate number of splicing plates 110, which can ensure that the first structure forms a good fit with the pre-sintered workpiece and the pre-sintered workpiece after sintering at each stage, and there is a large contact area between the two, thereby increasing the effect of preventing sintering deformation; it can also ensure that splicing the first structure is relatively simple.
[0053] Taking the pre-sintered workpiece as an annular shape as an example, the shape of the first space 120 is cylindrical. The number of the splicing plates 110 is 3 to 4. For example, the number is 3, and the three splicing plates 110 are spliced to form the first space 120 with a cylindrical inner diameter. The three splicing plates 110 are divided into three equal parts at about 120 degrees.
[0054] In some embodiments, the edges of the splicing plate 110 in the width direction are non-linear edges.
[0055] The edge of the splicing plate 110 in the width direction is a broken line, a curve, etc. For example, the splicing plate 110 is an S-shaped curve. The edge of the splicing plate 110 in the width direction is a non-linear edge, so that the edge of the splicing plate 110 in the width direction has a larger contact length with the pre-sintered workpiece or the pre-sintered workpiece after sintering in the width direction, which is more conducive to making the workpiece surface smooth.
[0056] The present application also provides a method for controlling the sintering deformation of cemented carbide, using the above-mentioned mold for controlling the sintering deformation of cemented carbide, the method for controlling the sintering deformation of cemented carbide includes:
[0057] S100: Sintering a green body corresponding to a target workpiece until a linear shrinkage rate reaches more than 95% to obtain a pre-sintered workpiece.
[0058] S200: attaching multiple splicing plates of the first mold to the pre-sintered workpiece respectively, surrounding each splicing plate in the width direction and arranging two adjacent splicing plates at intervals to form a first structure. The first structure forms an interference fit with the pre-sintered workpiece, and the interference is 0.5-3.0 mm.
[0059] S300: The second mold is mounted outside the first structure through the mounting hole, and sintering is continued until the pre-sintered workpiece is formed.
[0060] Since the method for controlling the sintering deformation of cemented carbide adopts the above-mentioned die for controlling the sintering deformation of cemented carbide, it also has the corresponding beneficial effects of the die for controlling the sintering deformation of cemented carbide, which will not be described in detail.
[0061] In some embodiments, the step of sintering a green body corresponding to a target workpiece until a linear shrinkage rate reaches more than 95% to obtain a pre-sintered workpiece comprises:
[0062] The green body is sintered at 1300° C. to 1350° C. until the linear shrinkage rate reaches 95%, thereby obtaining a pre-sintered workpiece.
[0063] The specific pre-sintering time varies according to the size of the workpiece. The sintering temperature can be set, and the pre-sintering time can be set as needed. Generally speaking, the specific pre-sintering time can be determined according to the complete sintering time of the target workpiece. The pre-sintering time is shorter than the complete sintering time, and the control line shrinkage rate can reach 95%. In some specific embodiments, the control line shrinkage rate reaches more than 99%.
[0064] At this sintering temperature, a pre-sintered workpiece with high sintering quality can be obtained.
[0065] In some embodiments, in the step of continuing sintering until the pre-sintered workpiece is formed, the sintering temperature is 1350-1500° C. and the sintering time is 60-75 minutes, that is, the sintering temperature is kept at the above sintering temperature for 60-75 minutes. Under this condition, a target workpiece with high sintering quality can be obtained.
[0066] In some embodiments, the target workpiece satisfies at least one of the following conditions: height ≥ 150 mm, binder phase ≥ 25 wt %, and ring shape.
[0067] The target workpiece that meets any one of the conditions of height ≥150mm, binder phase ≥25wt%, and ring shape is prone to sintering deformation in a general sintering process. Therefore, the method for controlling sintering deformation of cemented carbide of the present application can be used for sintering.
[0068] It is understandable that target workpieces with other structures that are relatively less prone to sintering deformation can also be sintered using the method for controlling sintering deformation of cemented carbide.
[0069] The technical solution of the present application is described below in conjunction with specific embodiments.
[0070] Example 1
[0071] The target workpiece in this Example 1 is a cemented carbide roller ring with a binder phase of 28.5 wt% and a height of 170 mm.
[0072] The cemented carbide roller ring is affected by the height and deadweight of the workpiece, and will have deformation problems such as bulging in the middle and lower part of the outer circle, enlarged inner hole, and shorter height. The size is difficult to control and the product qualification rate is less than 70%.
[0073] The method for controlling the sintering deformation of cemented carbide comprises the following steps:
[0074] 1. After removing the forming agent from the target part, pre-sinter it at 1320℃ and keep it warm for 60 minutes. At this time, the linear shrinkage rate of the workpiece reaches more than 99%, and a pre-sintered workpiece is obtained. At this time, the outer diameter of the roller ring is 354mm, the inner diameter is 236mm, and the height is 175mm.
[0075] Second, a mold for controlling the sintering deformation of cemented carbide is made according to the size of the pre-sintered workpiece, and the mold is a graphite kit.
[0076] The mold for controlling the sintering deformation of cemented carbide includes a first mold (Part B) and a second mold (Part A). Figure 1 , wherein the B part has three identical arc-shaped splicing plates. The three identical arc-shaped splicing plates are spliced along the width direction and spaced at a certain interval to form a first structure.
[0077] The inner diameter of the pre-sintered workpiece minus the first structure is 1.5 mm, and a certain pre-tightening force can be generated after being assembled together with the pre-sintered workpiece.
[0078] The taper of the outer surface of the first structure is 80°, and this angle design can facilitate the insertion of the A part. The taper angle of the tapered hole section inside the A part is equal to the taper angle.
[0079] 3. Wrap the outer circle of the workpiece with the B piece in the prepared graphite set, and put the A piece on the outside of the B piece, and then sinter the workpiece to the final temperature of 1370℃ and keep it warm for 75 minutes to make the physical properties meet the requirements. During the sintering process, the graphite A piece moves downward at an angle under the action of its own gravity, so as to achieve the purpose of locking the outer circle of the workpiece and preventing it from bulging and deforming.
[0080] A total of 20 cemented carbide roller rings were produced in this batch. All cemented carbide roller ring products have regular dimensions and the product size qualification rate reaches 100%.
[0081] Example 2
[0082] The target workpiece of the second embodiment is the same as the target workpiece of the first embodiment.
[0083] The method for controlling the sintering deformation of cemented carbide comprises the following steps:
[0084] 1. After removing the forming agent from the target part, keep it at 1350℃ for 30 minutes for pre-sintering. At this time, the linear shrinkage rate of the workpiece reaches more than 99.8%, and the pre-sintered workpiece is obtained. At this time, the outer diameter of the roller ring is 352.8mm, the inner diameter is 235.5mm, and the height is 173.8mm.
[0085] Second, a mold for controlling the sintering deformation of cemented carbide is made according to the size of the pre-sintered workpiece, and the mold is a graphite kit.
[0086] The mold for controlling the sintering deformation of cemented carbide includes a first mold (Part B) and a second mold (Part A). Figure 1 , wherein the B part has three identical arc-shaped splicing plates. The three identical arc-shaped splicing plates are spliced along the width direction and spaced at a certain interval to form a first structure.
[0087] The inner diameter of the pre-sintered workpiece minus the first structure is 0.5 mm, and a certain pre-tightening force can be generated after being assembled together with the pre-sintered workpiece.
[0088] The taper of the outer surface of the first structure is 85°, and this angle design can facilitate the insertion of the A part. The taper angle of the tapered hole section inside the A part is equal to the taper angle.
[0089] 3. Wrap the outer circle of the workpiece with the B piece in the prepared graphite kit, insert the A piece into the outside of the B piece, and then sinter the workpiece to the final temperature so that the physical properties meet the requirements. During the sintering process, the graphite A piece moves downward at an angle under the action of its own gravity, thereby achieving the purpose of locking the outer circle of the workpiece so that it does not bulge outward and deform.
[0090] A total of 5 cemented carbide roller rings were produced in this batch. All cemented carbide roller ring products have regular dimensions and the product size qualification rate reaches 100%.
[0091] Example 3
[0092] The target workpiece of the third embodiment is the same as the target workpiece of the first embodiment.
[0093] The method for controlling the sintering deformation of cemented carbide comprises the following steps:
[0094] 1. After removing the forming agent from the target part, pre-sinter it at 1325℃ and keep it warm for 60 minutes. At this time, the linear shrinkage rate of the workpiece reaches more than 99.4%, and the pre-sintered workpiece is obtained. At this time, the outer diameter of the roller ring is 353.7mm, the inner diameter is 236mm, and the height is 174.5mm.
[0095] Second, a mold for controlling the sintering deformation of cemented carbide is made according to the size of the pre-sintered workpiece, and the mold is a graphite kit.
[0096] The mold for controlling the sintering deformation of cemented carbide includes a first mold (Part B) and a second mold (Part A). Figure 1 , wherein the B part has three identical arc-shaped splicing plates. The three identical arc-shaped splicing plates are spliced along the width direction and spaced at a certain interval to form a first structure.
[0097] The inner diameter of the pre-sintered workpiece minus the first structure is 0.6 mm, which can generate a certain pre-tightening force after being assembled with the pre-sintered workpiece.
[0098] The taper of the outer surface of the first structure is 85°, and this angle design can facilitate the insertion of the A part. The taper angle of the tapered hole section inside the A part is equal to the taper angle.
[0099] 3. Wrap the outer circle of the workpiece with the B piece in the prepared graphite set, and put the A piece on the outside of the B piece, and then sinter the workpiece to the final temperature of 1370℃ and keep it warm for 75 minutes to make the physical properties meet the requirements. During the sintering process, the graphite A piece moves downward at an angle under the action of its own gravity, so as to achieve the purpose of locking the outer circle of the workpiece and preventing it from bulging and deforming.
[0100] A total of 16 cemented carbide roller rings were produced in this batch. All cemented carbide roller ring products have regular dimensions and the product size qualification rate reaches 100%.
[0101] Example 4
[0102] The target workpiece of the fourth embodiment is the same as the target workpiece of the first embodiment.
[0103] The method for controlling the sintering deformation of cemented carbide comprises the following steps:
[0104] 1. After removing the forming agent from the target part, pre-sinter it at 1325℃ and keep it warm for 60 minutes. At this time, the linear shrinkage rate of the workpiece reaches more than 99.4%, and the pre-sintered workpiece is obtained. At this time, the outer diameter of the roller ring is 353.7mm, the inner diameter is 236mm, and the height is 174.5mm.
[0105] Second, a mold for controlling the sintering deformation of cemented carbide is made according to the size of the pre-sintered workpiece, and the mold is a graphite kit.
[0106] The mold for controlling the sintering deformation of cemented carbide includes a first mold (Part B) and a second mold (Part A). Figure 1 , wherein the B part has four identical arc-shaped splicing plates. The four identical arc-shaped splicing plates are spliced along the width direction and spaced at a certain interval to form a first structure.
[0107] The inner diameter of the pre-sintered workpiece minus the first structure is 0.8 mm, and a certain pre-tightening force can be generated after being assembled together with the pre-sintered workpiece.
[0108] The taper of the outer surface of the first structure is 85°, and this angle design can facilitate the insertion of the A part. The taper angle of the tapered hole section inside the A part is equal to the taper angle.
[0109] 3. Wrap the outer circle of the workpiece with the B piece in the prepared graphite set, and put the A piece on the outside of the B piece, and then sinter the workpiece to the final temperature of 1370℃ and keep it warm for 75 minutes to make the physical properties meet the requirements. During the sintering process, the graphite A piece moves downward at an angle under the action of its own gravity, so as to achieve the purpose of locking the outer circle of the workpiece and preventing it from bulging and deforming.
[0110] This batch produced a total of 6 cemented carbide roller rings. All cemented carbide roller ring products have regular dimensions and the product size qualification rate reaches 100%.
[0111] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. A die for controlling sintering deformation of cemented carbide, characterized in that: include: A first mold includes a plurality of splicing plates, wherein the plurality of splicing plates can be respectively surrounded along the width direction of each splicing plate and two adjacent splicing plates are spaced apart to form a first structure; the first structure has a first space; the first space can form an interference fit with a pre-sintered workpiece, and the interference amount is 0.5 to 3.0 mm; the pre-sintered workpiece is a workpiece corresponding to a target workpiece, and the green body is sintered until the linear shrinkage rate reaches more than 95%; The second mold has a through mounting hole, and the mounting hole includes a tapered hole section with a diameter gradually increasing from bottom to top. The second mold is sleeved on the first structure through the mounting hole, and the first structure is constrained by the tapered hole section to follow the changes of the pre-sintered workpiece and fit the pre-sintered workpiece.
2. The die for controlling sintering deformation of cemented carbide according to claim 1, characterized in that: The first structure is a cone-like structure that gradually shrinks from bottom to top; the cone hole section matches the cone-like structure.
3. The die for controlling sintering deformation of cemented carbide according to claim 2, characterized in that: The cone angles of the cone hole section and the cone-like cylinder structure are both 75° to 85°.
4. The die for controlling sintering deformation of cemented carbide according to claim 3, characterized in that: The mounting hole also includes a cylindrical hole section coaxially arranged with the small end of the tapered hole section, and the diameter of the cylindrical hole section and the diameter of the small end of the tapered hole section are the same as the diameter of the small end of the cone-like cylinder.
5. The die for controlling sintering deformation of cemented carbide according to claim 1, characterized in that: The number of the splicing plates is 3 to 4, and the splicing plates are identical.
6. The die for controlling sintering deformation of cemented carbide according to any one of claims 1 to 5, characterized in that: The edges of the splicing plate in the width direction are non-linear edges.
7. A method for controlling sintering deformation of cemented carbide, characterized in that: The die for controlling the sintering deformation of cemented carbide according to any one of claims 1 to 6 is used, and the method for controlling the sintering deformation of cemented carbide comprises: Sintering a green body corresponding to a target workpiece until a linear shrinkage rate reaches more than 95% to obtain a pre-sintered workpiece; The plurality of splicing plates of the first mold are respectively attached to the pre-sintered workpiece, and are surrounded along the width direction of each splicing plate and spaced between two adjacent splicing plates to form a first structure; the first structure forms an interference fit with the pre-sintered workpiece, and the interference amount is 0.5 to 3.0 mm; The second mold is sleeved on the first structure through the mounting hole, and sintering is continued until the pre-sintered workpiece is formed.
8. The method for controlling sintering deformation of cemented carbide according to claim 7, characterized in that: The step of sintering the green body corresponding to the target workpiece until the linear shrinkage rate reaches more than 95% to obtain the pre-sintered workpiece comprises: The green body is sintered at 1300° C. to 1350° C. until the linear shrinkage rate reaches 95%, thereby obtaining a pre-sintered workpiece.
9. The method for controlling sintering deformation of cemented carbide according to claim 7, characterized in that: In the step of continuing sintering until the pre-sintered workpiece is formed, the sintering temperature is 1350-1500° C. and the sintering time is 60-75 minutes.
10. The method for controlling sintering deformation of cemented carbide according to any one of claims 7 to 9, characterized in that: The target workpiece at least meets at least one of the following conditions: height ≥150 mm, binder phase ≥25 wt%, and ring shape.