A homogeneous sintering mold and sintering method for superhard material grinding wheels

Abstract

The application discloses a kind of superhard material grinding wheel homogeneous sintering mould and sintering method, by the split movable block compression ring of sintering mould is handled by "calculus", using the same direction split three-rod hydraulic cylinder of upper and lower pair arrangement is respectively pressed to the upper and lower end surface of mould, the sintering process of grinding wheel ring uniform density, uniform heating is developed, the circumferential homogeneous sintering manufacturing of metal bond, metal matrix composite superhard material large thickness, narrow ring width grinding wheel ring is realized, the uneven grinding force, grinding resonance, abrasive shedding anomaly, wafer surface quality difference, grinding wheel instability, short life and other series of problems caused by the uneven material properties of metal bond, metal matrix composite grinding wheel are solved.

Description

Technical Field

[0001] This invention belongs to the field of homogeneous sintering technology for superhard material grinding wheels, and specifically relates to a homogeneous sintering mold and sintering method for superhard material grinding wheels. Background Technology

[0002] In the edge beveling grinding processes of semiconductor materials, liquid crystal glass, sapphire, and other materials, as workpiece thickness decreases, improving edge surface quality plays a crucial role in the yield of subsequent processes (etching, electroplating, heat treatment, etc.). Simultaneously, with increasingly fierce market competition, the stability, consistency, and lifespan requirements for superhard material grinding wheels with metal-based binders, such as metal-bonded, metal-resin-bonded, and metal-ceramic-bonded wheels used for beveling are also becoming increasingly stringent.

[0003] Chamfered grinding wheels are all circumferentially rotating grinding wheels. The outer circumference of the abrasive layer is mainly responsible for participating in the actual grinding process. The abrasive layer is mainly formed by hot pressing using a sintering press. Grinding wheel rings are characterized by large thickness and narrow ring width, which is not conducive to the hot pressing sintering process. With the increasing requirements for grinding quality, there are certain differences in the density, hardness, and crystal orientation of the circumference of the abrasive layer in grinding wheel rings produced by the traditional sintering press process. These differences cause abnormal changes in grinding force and grinding resonance during wafer grinding, which in turn leads to a series of problems such as wafer chipping, burrs, conchoidal cracks, premature shedding of superhard abrasive from the grinding wheel, and short wheel life. Therefore, ensuring the material uniformity of large thickness and narrow ring width grinding wheel rings made of superhard materials has become a difficult and painful problem that urgently needs to be solved.

[0004] Traditional sintering processes mainly have the following problems: Traditional hot pressing sintering presses typically use a single-column hydraulic cylinder, such as... Figure 1 and Figure 2As shown, during the hot pressing sintering process, the hydraulic cylinder directly acts on the upper pressure ring (lower pressure ring). There are two sintering methods: constant pressure hot pressing sintering and fixed mold hot pressing sintering. In the constant pressure hot pressing sintering mode, the outer mold sleeve and inner mold pillar do not contact the heat sink plate throughout the entire process, are not under pressure, and are in a free state; in the fixed mold hot pressing sintering mode, the outer mold sleeve and inner mold pillar do not contact the heat sink plate in the early stage, but when the upper and lower pressure rings are pressed to be flush with the end faces of the outer mold sleeve and inner mold pillar, the outer mold sleeve and inner mold sleeve come into contact with the heat sink plate. Because the heat sink plate and the outer mold sleeve and inner mold pillar do not contact each other or only come into contact with each other at the very end of the pressing process, uneven pressing is likely to occur during the sintering of the grinding wheel ring due to uneven friction or inconsistent fit of the auxiliary pressure ring. At the same time, the sintering press uses the contact between the upper and lower heat sink plates and the auxiliary pressure ring to remove heat and adjust the sintering temperature range. During the sintering process, the outer mold sleeve and inner mold cavity only come into contact with the heat sink plate in the later stage of the fixed mold sintering. There is a certain difference between the cooling rate of the auxiliary pressure ring and the cooling rate of the outer mold sleeve and inner mold cavity in the sintering area. As a result, the auxiliary pressure ring is prone to uneven stress and cracking, which leads to uneven pressure and inconsistent density of the grinding wheel ring, serious mold wear, poor product quality and waste of resources.

[0005] Question 1: The hydraulic cylinder of the traditional hot press applies a certain pressure to the entire grinding wheel ring. Because the volume of powder put into different positions of the grinding wheel ring is different, the density, hardness and other properties of the grinding wheel ring blank are different at different positions after hot pressing. Question 2: The sintering press uses resistance heating. The different densities of the grinding wheel rings cause a gradient difference in resistance at various points, which can lead to differences in the temperature field during resistance heating. At the same time, the sintering press uses a water-cooled heat sink plate to contact the pressure ring and remove heat to adjust the sintering temperature range. During the sintering process, the outer mold sleeve and inner mold cavity only come into contact with the heat sink plate in the later stage of sintering. This results in a certain difference between the cooling rate of the auxiliary pressure ring in the sintering area and the cooling rate of the outer mold sleeve and inner mold cavity throughout the entire process. Consequently, this leads to certain differences in the grain size, phase structure, phase distribution, and alloy composition distribution of the internal structure of the sintered blank.

[0006] Therefore, it is necessary to design a homogeneous hot pressing sintering method for grinding wheel rings using metal binders and metal-based composite binders to solve the problem of abnormal material distribution around the circumference of the grinding wheel ring caused by uneven pressing density and uneven heating. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art by providing a homogeneous sintering mold and sintering method for superhard material grinding wheels. This solves the problem of abnormal material on the circumference of the grinding wheel ring caused by uneven pressing density and uneven heating, and avoids a series of problems such as uneven grinding force, grinding resonance, and abnormal abrasive layer shedding. At the same time, it ensures stable grinding of wafers, and guarantees wafer surface quality and grinding wheel life.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A homogeneous sintering mold for a superhard material grinding wheel includes an outer mold sleeve, an inner mold column, and a split movable block pressure ring and an auxiliary pressure ring disposed in the mold cavity. The split movable block pressure ring and the auxiliary pressure ring are symmetrically arranged at the upper and lower ends of the mold cavity to form a double cylinder double end face pressing. Powder is filled in the mold cavity between the two split movable block pressure rings. High-strength spherical pressure equalizing tissue is also provided between the split-block pressure ring and the auxiliary pressure ring; The split movable block pressure ring includes N sector blocks that form a complete cylindrical ring, and each sector block is movable along the axial direction; During pressing, three-bar hydraulic cylinders arranged in pairs and moving in the same direction are used to apply pressure to the upper and lower end faces of the mold.

[0009] The co-directional split three-bar hydraulic cylinder includes a first hydraulic cylinder, a second hydraulic cylinder, and a third hydraulic cylinder nested in a ring from the outside to the inside, as well as a first pressure-bearing heat dissipation valve block disposed at the end of the piston rod of the first hydraulic cylinder and a second pressure-bearing heat dissipation valve block disposed at the end of the piston rod of the third hydraulic cylinder, and the inlet and outlet of the three hydraulic cylinders are controlled independently. The first hydraulic cylinder is used to apply pressure to the outer mold sleeve, the second hydraulic cylinder is used to apply pressure to the auxiliary pressure ring, and the third hydraulic cylinder is used to apply pressure to the inner mold column. Both the first and second pressure-bearing heat dissipation valve blocks are provided with cooling circuits for heat dissipation, and the coolant for both is supplied through the same branch.

[0010] The first hydraulic cylinder and the second hydraulic cylinder have the same structure and both include a cylinder barrel, a piston assembly and an annular piston rod disposed in the cylinder barrel, as well as an oil inlet and an oil outlet. An oil distribution and pressure equalization chamber is provided at the connection between the annular piston rod and the piston assembly, and the oil distribution and pressure equalization chamber forms a connected space between the oil cylinders separated by the annular piston rod in the cylinder barrel.

[0011] The high-pressure oil pipes connected to the oil outlets of the second and third hydraulic cylinders are led out through the pressure-bearing oil supply connection pipe opened on the first pressure-bearing heat dissipation valve block.

[0012] The cooling circuit is distributed in annular water channels on both the first and second pressure-bearing heat dissipation valve blocks.

[0013] A high-strength annular transition sleeve is fitted onto the inner wall of the outer mold sleeve, and a high-strength annular transition sleeve is also fitted onto the outer wall of the inner mold column.

[0014] Both the first and second pressure-bearing heat dissipation valve blocks are equipped with heat insulation plates, which are arranged above the cooling circuit and adjacent to the piston rod end.

[0015] A sintering method for a homogeneous sintering mold for a superhard material grinding wheel includes the following steps: a. Film application (1) Assemble the mold, connect the outer mold sleeve and the inner mold column, and install the auxiliary pressure ring under the mold; (2) Place the outer mold sleeve and inner mold column on the pad, and then place the high-strength spherical uniform pressure tissue on the upper part of the auxiliary pressure ring; (3) Use an ultrasonic vibrator to uniformly compact the high-strength spherical uniform pressure tissue, and use a tool to place the lower split block pressure ring at the bottom of the mold cavity. Weigh the powder and place it evenly in the mold cavity. Use a tool to evenly distribute the abrasive layer. (4) Use tooling to place the upper split block pressure ring on the powder, place the high-strength spherical uniform pressure structure and distribute it evenly, and finally place the upper auxiliary pressure ring; b. Hot pressing and sintering (5) Place the assembled mold on the worktable of the second hydraulic cylinder. First, start the first and third hydraulic cylinders above and below the mold and set the pressure P. After the pressure is reached, the first and third hydraulic cylinders stop working. Under the pressure, the outer mold sleeve and the first pressure-bearing heat dissipation valve block at the end of the piston rod of the first hydraulic cylinder are in stable contact, and the inner mold column and the second pressure-bearing heat dissipation valve block at the end of the piston rod of the third hydraulic cylinder are in stable contact. (6) Start the second hydraulic cylinder. Under the action of the upper and lower second hydraulic cylinders, drive the upper and lower auxiliary pressure rings to move towards each other. The force is transmitted through the auxiliary pressure rings to the high-strength spherical pressure equalizing tissue. The high-strength spherical pressure equalizing tissue decomposes the force to the split movable block pressure ring. (7) After pressing is completed, the piston rods of the upper and lower second hydraulic cylinders are retracted, and then the upper and lower first and third hydraulic cylinders are started to retract. After reaching the set position, the mold is removed and the mold is unloaded to complete the entire process.

[0016] In step (5), both the first and third hydraulic cylinders are locked with a two-way self-locking valve.

[0017] The beneficial effects of this invention are: (1) This invention discloses a homogeneous sintering mold and sintering method for superhard material grinding wheels. By performing "integralization" on the split movable block pressure ring of the sintering mold, and using two pairs of unidirectional split three-bar hydraulic cylinders to press the upper and lower end faces of the mold respectively, a sintering process with uniform density and uniform heating of the grinding wheel ring is developed. This realizes the circumferential homogeneous sintering manufacturing of metal-bonded, metal-based composite superhard material large thickness, narrow ring and wide ring grinding wheels. It solves a series of problems caused by uneven grinding force, grinding resonance, abnormal abrasive shedding, poor wafer surface quality, unstable grinding wheel and short life caused by uneven circumferential material properties of metal-bonded, metal-based composite material grinding wheels.

[0018] (2) The split movable block compression ring is divided into "differential integral" division, and the whole compression ring is decomposed into N evenly distributed movable blocks. The single whole ring force surface is transformed into N force surfaces to ensure that the force on each force surface is consistent during the pressing process and the pressure transmitted to the powder is consistent. Because the weight of the abrasive layer corresponding to each force surface is different in actual implementation, the compression amount is large for the place with smaller weight and small for the place with larger weight. N evenly distributed movable blocks can ensure that the density of the abrasive layer corresponding to each force surface is consistent. At the same time, it ensures that the induction resistance at different positions is relatively consistent, and then the local temperature field formed by the sintering press at each position is consistent.

[0019] (3) The process of using double cylinder double end face pressing, using upper and lower hydraulic cylinders to apply constant pressure to the outer mold sleeve and inner mold column of the mold, and then pressurizing and sintering the powder, and transforming the traditional single-rod hydraulic cylinder at one end into a three-rod hydraulic cylinder in the same direction. The inner and outer ring cylinder rods are used for fixing the outer ring of the mold and laying out the heat dissipation plate, while the middle ring cylinder rod is mainly used for pressurizing the abrasive layer to ensure close contact between the heat dissipation plate and the mold during the sintering process, forming a stable and uniform temperature circulation path. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a traditional hot-pressing sintering mold; Figure 2 This is a traditional grinding wheel ring density distribution diagram; Figure 3 This is a schematic diagram of the structure of the movable block pressure equalization mold of the present invention; Figure 4 This is a schematic diagram of the structure of the split-block pressure ring; Figure 5 This is a schematic diagram of the pressing process of the movable block equalization mold of the present invention; Figure 6 This is a simplified structural diagram of a unidirectional split three-bar hydraulic cylinder; Figure 7 This is a schematic diagram of a unidirectional split three-bar hydraulic cylinder; Figure 8 This is a schematic diagram of the cylinder body of a unidirectional split three-bar hydraulic cylinder; Figure 9 This is a schematic diagram of a bidirectional pressing mechanism using a three-bar hydraulic cylinder with a single-direction split design; Figure 10 This is a schematic diagram of the pressing process of a unidirectional split three-bar hydraulic cylinder; Figure 11 This is a density distribution diagram of the grinding wheel ring obtained by the present invention; Figure 12 The workpiece exhibits shell-like cracks due to traditional sintering methods; Figure 13 The burrs on the workpiece are produced by traditional sintering methods; Figure 14 This is a schematic diagram of the edge of the workpiece obtained by the sintering method of the present invention. Detailed Implementation

[0021] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0022] This invention provides a homogeneous sintering mold and sintering method for superhard material grinding wheels, such as... Figures 3 to 14 As shown.

[0023] A homogeneous sintering mold for a superhard material grinding wheel includes an outer mold sleeve 1, an inner mold pillar 2, and a split movable block pressure ring 3 and an auxiliary pressure ring 4 disposed in the mold cavity. The split movable block pressure ring 3 and the auxiliary pressure ring 4 are symmetrically arranged at the upper and lower ends of the mold cavity to form a double-cylinder double-end-face pressing. Powder 5 is filled in the mold cavity between the two split movable block pressure rings 3. A high-strength spherical pressure equalizing structure 7 is also provided between the split movable block pressure ring 3 and the auxiliary pressure ring 4. The split movable block pressure ring 3 includes N sector blocks that form a complete cylindrical ring, and each sector block is movable along the axial direction. During pressing, a pair of unidirectional split three-bar hydraulic cylinders are used to apply pressure to the upper and lower end faces of the mold.

[0024] In this embodiment, the outer mold sleeve 1 is a circular cylinder made of graphite or cast iron, which is a mold shape control component. The inner wall of the outer mold sleeve 1 is also fitted with a high-strength annular low-roughness transition sleeve 6.

[0025] The inner mold column 2 is a cylinder made of graphite or cast iron and is a component for controlling the inner hole size of the mold. The outer wall of the inner mold column 2 is inlaid with a high-strength annular low-roughness transition sleeve by means of a sleeve connection.

[0026] The high-strength annular low-roughness transition sleeve 6 is about 5~10mm thick and is made of silicon carbide or alumina material with good high temperature resistance, impact resistance and wear resistance. The surface roughness reaches Ra0.4 or less. It can maintain its shape, size and surface roughness during multiple hot pressing and sintering. It can effectively reduce the mold wall friction force generated by the powder in the height direction after being pressed and reduce the density difference in the height direction.

[0027] A high-strength spherical pressure equalization structure 7 and a split movable block pressure ring 3 are also provided between the powder 5 and the auxiliary pressure ring 4.

[0028] The high-strength spherical uniform pressure structure 7 is composed of high-strength zirconia (silicon carbide, alumina) microspheres with different particle diameters (φ0.5~φ5mm); The split-type movable block pressure ring 3 is composed of N sector blocks forming a complete cylindrical ring, and each sector block can move along the axial direction.

[0029] In this embodiment, both the upper and lower auxiliary pressure rings 4 adopt a T-shaped circular cylindrical structure. During the pressing process, the pressure is transmitted to the high-strength spherical uniform pressure structure through the auxiliary pressure rings 4. Subsequently, the pressure is decomposed and transmitted to the segmented movable pressure rings 3. Each segment receives equal pressure, which is pressed onto the powder at different locations. The pressure on each part of the powder is relatively consistent, so that the density of each part of the grinding wheel ring is consistent. On the other hand, it improves the surface quality of the mold in contact with the powder and reduces the friction between the powder and the mold wall.

[0030] The specific operation process is as follows: Step 1: Assemble the mold First, assemble the mold by connecting the outer mold sleeve 1 and the inner mold column 2, and install the lower auxiliary pressure ring 4 of the mold. Secondly, a certain volume of high-strength spherical homogeneous tissue is placed into the mold cavity and flattened. Next, place the separate live block compression ring onto the high-strength spherical uniform pressure tissue; Next, a certain weight of powder is evenly introduced into the mold cavity and spread out. Next, place the split-type movable block pressure ring on the split-type part; Finally, place the auxiliary pressure ring on the split movable block pressure ring.

[0031] Step Two: Suppression.

[0032] The upper and lower auxiliary pressure rings are subjected to pressure F1 and F2 from the hydraulic cylinders. The pressure is transmitted to the high-strength spherical uniform pressure structure and evenly distributed to the split movable block pressure rings. Each split movable block pressure ring receives the same pressure, and the powder in different positions receives the same pressure. Because the powder quality of each part has a certain difference, under a certain pressure, the split movable block pressure rings move in different positions, thereby achieving uniform powder density. In addition, due to the good surface quality of the inner and outer walls of the mold cavity and the low friction, the difference in the movement and displacement of the powder in the axial section during the pressing process is small, ultimately achieving a grinding wheel ring with consistent density.

[0033] The unidirectional split three-bar hydraulic cylinder includes a first hydraulic cylinder 8, a second hydraulic cylinder 9, and a third hydraulic cylinder 10 nested in a ring from the outside to the inside, as well as a first pressure-bearing heat dissipation valve block 11 and a second pressure-bearing heat dissipation valve block 12 disposed at the end of the piston rod of the first hydraulic cylinder and disposed at the end of the piston rod of the third hydraulic cylinder, and the inlet and outlet of the three hydraulic cylinders are controlled independently. The first hydraulic cylinder 8 is used to apply pressure to the outer mold sleeve, the second hydraulic cylinder 9 is used to apply pressure to the auxiliary pressure ring, and the third hydraulic cylinder 10 is used to apply pressure to the inner mold column. Both the first pressure-bearing heat dissipation valve block 11 and the second pressure-bearing heat dissipation valve block 12 are provided with cooling circuits for heat dissipation, and the coolant of the two is connected to the same branch to ensure that the heat conduction of the cooling water inlet and outlet is consistent, thereby ensuring that the temperature control rate of the outer mold sleeve and the inner mold column is consistent. In order to reduce the cooling water resistance, the cooling circuits are distributed in annular water channels on both the first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block.

[0034] In this embodiment, the first hydraulic cylinder 8 and the second hydraulic cylinder 9 are structurally identical, and both include a cylinder barrel, an end cover, a piston assembly and an annular piston rod disposed in the cylinder barrel, as well as an oil inlet and an oil outlet; the piston assembly and the annular piston rod are both annular ring structures. An oil distribution and pressure equalization chamber 89 is provided at the connection between the annular piston rod and the piston assembly, and the oil distribution and pressure equalization chamber 89 forms a connecting space between the cylinders separated by the annular piston rod within the cylinder barrel.

[0035] The flexible high-pressure oil pipe 1001 connected to the oil outlet 94 of the second hydraulic cylinder 9 and the oil outlet 104 of the third hydraulic cylinder 10 is led out through the pressure-bearing oil supply connection pipe opened on the first pressure-bearing heat dissipation valve block 11.

[0036] A high-strength annular transition sleeve is fitted onto the inner wall of the outer mold sleeve, and a high-strength annular transition sleeve is also fitted onto the outer wall of the inner mold column.

[0037] Both the first and second pressure-bearing heat dissipation valve blocks are equipped with heat insulation plates, which are arranged above the cooling circuit and adjacent to the piston rod end.

[0038] The first hydraulic cylinder 1 and the second hydraulic cylinder 2 apply pressure to the inner mold pillar and outer mold sleeve of the mold, which plays a role in fixing and applying appropriate pressure to ensure stable heat conduction; the second hydraulic cylinder applies pressure to the auxiliary pressure ring of the mold to complete the pressing work.

[0039] The third hydraulic cylinder 10 includes a third piston rod 103, a third piston assembly 102, and an end cap, all of which are of conventional type. The third hydraulic cylinder is also equipped with a third oil inlet 101 and a fourth oil outlet 104. The fourth oil outlet is led out through a flexible high-pressure oil pipe connected to the end cap assembly and a pressure-bearing oil supply connection channel 85 on the first pressure-bearing heat dissipation valve block 11.

[0040] The cylinder barrels of the three hydraulic cylinders share a common base, on which the oil inlets of the three hydraulic cylinders are arranged; the outer wall of the cylinder barrel of the third hydraulic cylinder serves as the inner wall of the cylinder barrel of the second hydraulic cylinder; and the outer wall of the cylinder barrel of the second hydraulic cylinder serves as the inner wall of the cylinder barrel of the first hydraulic cylinder.

[0041] When hydraulic oil at a certain pressure is supplied to the oil inlet 81 of the first hydraulic cylinder 8, the first piston assembly 82 begins to move under the pressure of the hydraulic oil, driving the first annular piston rod 83 to move upward, and then the first pressure-bearing heat dissipation valve block 11 moves. When a certain amount of hydraulic oil is supplied to the inlet 91 of the second hydraulic cylinder 9, the second piston assembly 92 moves the second annular piston rod 93 under the action of hydraulic oil pressure, which in turn moves the pressure block upward. The inlet 101 of the third hydraulic cylinder 10 is supplied with hydraulic oil at a certain pressure. Under the action of the hydraulic oil pressure, the third piston assembly 102 drives the third piston rod 103 to move, which in turn drives the second pressure-bearing heat dissipation valve block 12 to move upward.

[0042] In actual operation, the first and third hydraulic cylinders are mainly responsible for applying a certain pressure to the outer mold sleeve and inner mold pillar of the given mold, and ensuring that the heat dissipation plate is in large-area contact with the outer mold sleeve and inner mold cavity, so as to ensure that the thermal conductivity coefficients of the outer mold sleeve, inner mold cavity and heat dissipation plate and the auxiliary pressure ring and heat dissipation plate are consistent during the sintering process; the second hydraulic cylinder is mainly responsible for providing pressing pressure to the auxiliary pressure ring for actual pressing work.

[0043] Specific methods: Prepare a certain volume of powder and a movable block equalization mold in advance, and set the sintering press program according to the design.

[0044] a. Film application The height H of the powder after molding is calculated based on the design. The height H1 of the split-block pressure ring, the high-strength spherical uniformly compressed structure H2, and the outer mold sleeve H4 are also known. According to the design requirements, the height of the powder after hot pressing is h, and the thickness difference of the powder after heating and pressurizing from H is Hh. Therefore, the height H3 of the corresponding T-shaped pressure ring can be selected.

[0045] (1) Assemble the mold, connect the outer mold sleeve and the inner mold column, and install the auxiliary pressure ring under the mold; (2) Place the outer mold sleeve and inner mold column on the pad, and then place the high-strength spherical uniform pressure tissue on the upper part of the lower T-shaped pressure ring; (3) Use an ultrasonic vibrator to uniformly compact the high-strength spherical uniformly pressure tissue, and use a tool to place the lower split movable block pressure ring at the bottom of the mold cavity. Weigh a certain weight of powder and place it evenly in the mold cavity. Use a tool to evenly distribute the abrasive layer. (4) Use tooling to place the upper split block pressure ring on the powder, place a certain amount of high-strength spherical uniform pressure structure and distribute it evenly, and finally place the upper auxiliary pressure ring. b. Hot pressing and sintering (5) Place the assembled mold on the worktable of the second hydraulic cylinder. Use a three-bar hydraulic cylinder with the upper and lower parts in the same direction to avoid the problem of inconsistent movement of the upper and lower pressure rings during unidirectional pressure application.

[0046] First, the first hydraulic cylinder 8 and the third hydraulic cylinder 10 above and below the mold are activated, and the pressure P is set. Once the pressure is reached, the first hydraulic cylinder 8 and the third hydraulic cylinder 10 stop working, and the pressure is converted into a force F.g1 F g1 '、 / F g3 F g3 Under pressure, the outer mold sleeve 1 and the first pressure-bearing heat dissipation valve block 11 at the end of the piston rod of the first hydraulic cylinder are in stable contact, and the inner mold column 2 and the second pressure-bearing heat dissipation valve block 12 at the end of the piston rod of the third hydraulic cylinder are in stable contact. The first hydraulic cylinder 8 and the third hydraulic cylinder 10 are locked with bidirectional self-locking valves to ensure the relative position of the mold and realize stable heat exchange between the outer mold sleeve 1, the inner mold column and the pressure-bearing heat dissipation valve block.

[0047] (6) Start the second hydraulic cylinder 9, and the upper and lower second hydraulic cylinders are under the action of force F g2 F g2 Under the action, the upper and lower auxiliary pressure rings 4 move in opposite directions. The force is transmitted through the auxiliary pressure rings to the high-strength spherical pressure equalizing tissue. The high-strength spherical pressure equalizing tissue decomposes the force to the separate movable block pressure rings. Each separate movable pressure ring transmits pressure to the corresponding powder below. Due to differences in weight and volume, the compression of each local powder varies slightly, but the pressure is consistent. At the same time, due to the internal resistance induction heating of the powder, a series of reactions occur. Meanwhile, the heat is conducted and adjusted by the upper and lower first and second pressure-bearing heat dissipation valve blocks, so that the internal heat rise and fall process and rate of the powder are consistent with the theoretical design, ultimately forming a grinding wheel ring with uniform density and consistent microstructure.

[0048] (7) After pressing is completed, the piston rods of the upper and lower second hydraulic cylinders are retracted, and then the upper and lower first and third hydraulic cylinders are started to retract. After reaching the set position, the mold is removed and the mold is unloaded to complete the entire process.

[0049] The following detailed description, in conjunction with specific embodiments, further illustrates the point: Using the homogeneous sintering mold and sintering method for superhard material grinding wheels disclosed in this invention, a grinding wheel ring with an outer diameter of φ300mm, a thickness of 60mm, and a wall thickness of 5mm and a metal-resin composite binder is pressed.

[0050] To test the effect, the grinding wheel ring was pressed using the method of this invention and its hardness was tested. To accurately measure the hardness, no superhard material was added to the test powder. The designed weight of the powder was 3.8 kg (without superhard material). The split-block pressing ring was divided into 72 equal blocks. The high-strength spherical uniform pressing structure was composed of zirconia spheres with average diameters of φ0.5 mm and φ0.2 mm combined in a ratio of 1:2.

[0051] First, the outer mold sleeve and inner mold column are fixed by upper and lower first hydraulic cylinders and third hydraulic cylinders. Then, the pressure is transmitted to the high-strength spherical uniform pressure structure through upper and lower auxiliary pressure rings by upper and lower second hydraulic cylinders. The pressure is further transmitted to the powder through the split movable block pressure ring. During the pressure transmission process, a 420° pressure sintering curve is used to complete the sintering of the powder under uniform pressure conditions.

[0052] The hardness of the grinding wheel ring end face was tested using a dedicated hardness tester. The measurement data compared with the traditional pressing method is shown in Table 1. The density distribution is illustrated in the figure below. Figure 11 .

[0053] Table 1. Comparison of Hardness of Grinding Wheel Ring End Face In addition, using the method of this invention, a metal-resin composite bonded superhard material grinding wheel with a diameter of φ202mm, a ring width of 4mm, a thickness of 20mm, and a diamond grit size of 800# was fabricated to grind silicon carbide wafers. This process was compared with traditional sintering methods (such as...). Figure 12 and Figure 13 As shown in the image, the grinding effect is evident, with significant improvement in chipping, elimination of shell cracks, and enhanced grinding stability. Figure 14 ).

[0054] If this patent uses terms such as "first" and "second" to define components, those skilled in the art should know that the use of "first" and "second" is merely for the convenience of describing the invention and simplifying the description, and the above terms have no special meaning.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0056] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

Claims

1. A homogeneous sintering mold for superhard material grinding wheels, characterized in that: It includes an outer mold sleeve, an inner mold column, and a split movable block pressure ring and an auxiliary pressure ring arranged in the mold cavity. The split movable block pressure ring and the auxiliary pressure ring are symmetrically arranged at the upper and lower ends of the mold cavity to form a double cylinder double end face pressing. The powder is filled in the mold cavity between the two split movable block pressure rings. The split-block pressure ring and the auxiliary pressure ring are also equipped with a high-strength spherical pressure equalization structure. The high-strength spherical pressure equalization structure is composed of high-strength zirconia microspheres with different particle diameters ranging from φ0.5 to φ5 mm. The split movable block pressure ring includes N sector blocks that form a complete cylindrical ring, and each sector block is movable along the axial direction; During pressing, a pair of unidirectional three-bar hydraulic cylinders are used to apply pressure to the upper and lower end faces of the mold. The co-directional split three-bar hydraulic cylinder includes a first hydraulic cylinder, a second hydraulic cylinder, and a third hydraulic cylinder nested in a ring from the outside to the inside, as well as a first pressure-bearing heat dissipation valve block disposed at the end of the piston rod of the first hydraulic cylinder and a second pressure-bearing heat dissipation valve block disposed at the end of the piston rod of the third hydraulic cylinder, and the inlet and outlet of the three hydraulic cylinders are controlled independently. The first hydraulic cylinder is used to apply pressure to the outer mold sleeve, the second hydraulic cylinder is used to apply pressure to the auxiliary pressure ring, and the third hydraulic cylinder is used to apply pressure to the inner mold column. The first and second pressure-bearing heat dissipation valve blocks are also provided with cooling circuits for heat dissipation, and the coolant of the two is from the same branch. The first hydraulic cylinder and the second hydraulic cylinder have the same structure and both include a cylinder barrel, a piston assembly and an annular piston rod disposed in the cylinder barrel, as well as an oil inlet and an oil outlet. An oil distribution and pressure equalization chamber is provided at the connection between the annular piston rod and the piston assembly, and the oil distribution and pressure equalization chamber forms a connected space between the oil cylinders in the cylinder barrel that are separated by the annular piston rod. The high-pressure oil pipes connected to the oil outlets of the second and third hydraulic cylinders are led out through the pressure-bearing oil supply connection pipe opened on the first pressure-bearing heat dissipation valve block. The cooling circuit is distributed in annular water channels on both the first and second pressure-bearing heat dissipation valve blocks.

2. The homogeneous sintering mold for a superhard material grinding wheel according to claim 1, characterized in that: A high-strength annular transition sleeve is fitted onto the inner wall of the outer mold sleeve, and a high-strength annular transition sleeve is also fitted onto the outer wall of the inner mold column.

3. The homogeneous sintering mold for a superhard material grinding wheel according to claim 1, characterized in that: Both the first and second pressure-bearing heat dissipation valve blocks are equipped with heat insulation plates, which are arranged above the cooling circuit and adjacent to the piston rod end.

4. A sintering method for a homogeneous sintering mold for a superhard material grinding wheel according to any one of claims 1 to 3, characterized in that, Includes the following steps: a. Film application (1) Assemble the mold, connect the outer mold sleeve and the inner mold column, and install the auxiliary pressure ring under the mold; (2) Place the outer mold sleeve and inner mold column on the pad, and then place the high-strength spherical uniform pressure tissue on the upper part of the auxiliary pressure ring; (3) Use an ultrasonic vibrator to uniformly compact the high-strength spherical uniform pressure tissue, and use a tool to place the lower split block pressure ring at the bottom of the mold cavity. Weigh the powder and place it evenly in the mold cavity. Use a tool to evenly distribute the abrasive layer. (4) Use tooling to place the upper split block pressure ring on the powder, place the high-strength spherical uniform pressure structure and distribute it evenly, and finally place the upper auxiliary pressure ring; b. Hot pressing and sintering (5) Place the assembled mold on the worktable of the second hydraulic cylinder. First, start the first and third hydraulic cylinders above and below the mold and set the pressure P. After the pressure is reached, the first and third hydraulic cylinders stop working. Under the pressure, the outer mold sleeve and the first pressure-bearing heat dissipation valve block at the end of the piston rod of the first hydraulic cylinder are in stable contact, and the inner mold column and the second pressure-bearing heat dissipation valve block at the end of the piston rod of the third hydraulic cylinder are in stable contact. (6) Start the second hydraulic cylinder. Under the action of the upper and lower second hydraulic cylinders, drive the upper and lower auxiliary pressure rings to move towards each other. The force is transmitted through the auxiliary pressure rings to the high-strength spherical pressure equalizing tissue. The high-strength spherical pressure equalizing tissue decomposes the force to the split movable block pressure ring. (7) After pressing is completed, the piston rods of the upper and lower second hydraulic cylinders are retracted, and then the upper and lower first and third hydraulic cylinders are started to retract. After reaching the set position, the mold is removed and the mold is unloaded to complete the entire process.

5. The homogeneous sintering mold and sintering method for a superhard material grinding wheel according to claim 4, characterized in that: In step (5), both the first and third hydraulic cylinders are locked with a two-way self-locking valve.

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