Superhard material grinding wheel homogeneous sintering mold and sintering method

Abstract

The invention discloses a superhard material grinding wheel homogeneous sintering mold and a sintering method, which are characterized in that a split loose piece pressing ring of the sintering mold is subjected to calculus treatment, and equidirectional split three-rod hydraulic cylinders which are arranged in pairs up and down are adopted to respectively apply pressure to the upper and lower end faces of the mold, so that a sintering process of a grinding wheel ring with uniform density and uniform heating is developed; the circumferential homogeneous sintering manufacturing of a large-thickness narrow-ring-width grinding wheel ring made of a metal bonding agent and a metal-based composite superhard material is realized, and a series of problems of non-uniform grinding force, grinding resonance, abnormal grinding material falling, poor wafer surface quality, unstable grinding wheel, short service life and the like caused by non-uniform circumferential material properties of the grinding wheel made of the metal bonding agent and the metal-based composite material are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of homogeneous sintering of superhard material grinding wheels, and in particular relates to a homogeneous sintering mold and a sintering method for superhard material grinding wheels. Background Art

[0002] In the edge chamfering and grinding process of semiconductor materials, liquid crystal glass, sapphire, etc., as the thickness of the workpiece becomes thinner and thinner, the improvement of the edge surface quality plays a vital role in the yield rate of the workpiece in the subsequent processes (corrosion, electroplating, heat treatment, etc.). At the same time, as the market competition becomes increasingly fierce, the stability, consistency and life requirements of superhard material grinding wheels with metal-based binders such as metal binders, metal-resin binders, and metal-ceramic binders used for chamfering are also becoming higher and higher.

[0003] Chamfered grinding wheels are all circular rotating structure grinding wheels. The outer circle of the abrasive layer is mainly responsible for the actual grinding process, and the abrasive layer is mainly formed by hot pressing using a sintering press. The grinding wheel ring has the characteristics of large thickness and narrow ring width, which is not friendly to the hot pressing sintering process. With the improvement of grinding quality requirements, there are certain differences in the density, hardness, and crystal orientation structure of the abrasive layer of the grinding wheel ring produced by the firing process of the traditional sintering press. This difference causes abnormal changes in grinding force and grinding resonance during the wafer grinding process, which in turn causes a series of problems such as wafer edge collapse, burrs, shell cracks, premature shedding of superhard abrasives on the grinding wheel, and short life. Therefore, the material uniformity of the superhard material's large thickness and narrow ring width grinding wheel ring has become a difficulty and pain point that needs to be solved urgently.

[0004] The traditional sintering process mainly has the following problems: Traditional hot pressing sintering presses generally use single-column hydraulic cylinders, such as Figure 1 and Figure 2As shown in the figure, during the hot pressing sintering process, the hydraulic cylinder directly acts on the upper pressure ring (lower pressure ring). There are two ways of sintering: fixed pressure hot pressing sintering and fixed die hot pressing sintering. In the fixed pressure hot pressing sintering mode, the outer mold sleeve and the inner mold column do not contact the heat sink during the entire process, are not subject to pressure, and are in a free state; in the fixed die hot pressing sintering mode, the outer mold sleeve and the inner mold column do not contact the heat sink in the early stage. When the upper and lower pressure rings are pressed to be flush with the end faces of the outer mold sleeve and the inner mold column, the outer mold sleeve and the inner mold sleeve contact the heat sink. Because the heat sink and the outer mold sleeve and the inner mold column are not in contact or are pressed and contacted at the end of pressing, during the sintering process of the grinding wheel ring, uneven pressing of the upper and lower parts may occur due to uneven friction or inconsistent matching of the auxiliary pressure ring. At the same time, the sintering press uses upper and lower heat sinks to contact the auxiliary pressure ring to take away heat to adjust the sintering temperature area. During the sintering process, the outer mold sleeve and the inner mold cavity are in contact with the heat sink only in the later stage of fixed mold sintering. There is a certain difference in the cooling rate of the auxiliary pressure ring and the cooling rate of the outer mold sleeve and the inner mold cavity in the sintering area. As a result, the auxiliary pressure ring is prone to cracking due to uneven force, resulting in uneven pressure on the grinding wheel ring, inconsistent density, serious mold loss, etc., resulting in poor product quality and waste of resources.

[0005] Problem 1: The hydraulic cylinder of the traditional hot press applies a certain pressure to the entire grinding wheel ring. Because the volume of powder placed at different positions of the grinding wheel ring is different, after hot pressing, the density, hardness and other properties of the grinding wheel ring blank at different positions are different. Question 2: The sintering press uses the resistance effect for heating. The different densities of the grinding wheel ring lead to gradient differences in resistance at various locations, and the temperature field during resistance heating is prone to certain differences. At the same time, the sintering press uses a water-cooled heat sink to contact the pressure ring to take away heat to adjust the sintering temperature area. During the sintering process, the outer mold sleeve and the inner mold cavity are in contact with the heat sink only in the later stage of sintering, resulting in a certain difference in the cooling rate of the auxiliary pressure ring in the sintering area and the cooling rate of the outer mold sleeve and the inner mold cavity during the whole process, which in turn causes certain differences in the internal grain size, phase structure, phase distribution, and alloy component distribution of the sintered blank.

[0006] Therefore, it is necessary to design a homogeneous hot pressing sintering method for metal binder and metal-based composite binder grinding wheel ring to solve the problem of abnormal circumferential material of the grinding wheel ring caused by uneven pressing density and uneven heating. Summary of the invention

[0007] The purpose of the present invention is to provide a homogeneous sintering mold and sintering method for a superhard material grinding wheel in view of the deficiencies in the above-mentioned prior art, which solves the problem of abnormal material of the circumference of the grinding wheel ring caused by uneven pressing density and uneven heating, avoids a series of problems such as uneven grinding force, grinding resonance, abnormal shedding of the abrasive layer, etc., and at the same time ensures stable grinding of the wafer, ensuring the surface quality of the wafer and the life of the grinding wheel.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: A superhard material grinding wheel homogenizing sintering die, comprising an outer die sleeve, an inner die column, and a split live block pressure ring and an auxiliary pressure ring arranged in a die cavity, wherein the split live block pressure ring and the auxiliary pressure ring are symmetrically arranged at the upper and lower ends of the die cavity to form a double-cylinder double-end surface pressing, and powder is filled in the die cavity between the two split live block pressure rings; A high-strength spherical pressure-equalizing structure is provided between the split live block pressure ring and the auxiliary pressure ring; The split movable block pressure ring includes N sector blocks forming a complete cylindrical ring body, and each sector block is movable along the axial direction; During pressing, the upper and lower end surfaces of the mold are pressed respectively by using the same-direction split three-rod hydraulic cylinders arranged in pairs up and down.

[0009] The same-direction split three-rod hydraulic cylinder comprises a first hydraulic cylinder, a second hydraulic cylinder and a third hydraulic cylinder which are annularly nested in sequence from outside to inside, and a first pressure-bearing heat-dissipating valve block correspondingly arranged at the end of the piston rod of the first hydraulic cylinder and a second pressure-bearing heat-dissipating valve block arranged at the end of the piston rod of the third hydraulic cylinder, and the liquid inlet and liquid return of the three hydraulic cylinders are independently controlled; The first hydraulic cylinder is used to press the outer mold sleeve, the second hydraulic cylinder is used to press the auxiliary pressure ring, and the third hydraulic cylinder is used to press the inner mold column; The first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block are both provided with cooling circuits for heat dissipation, and the cooling fluids of the two are in the same branch.

[0010] The first hydraulic cylinder and the second hydraulic cylinder are identically configured and both include a cylinder barrel, a piston assembly and an annular piston rod disposed in the cylinder barrel, and an oil inlet and an oil outlet; An oil separation and pressure equalization cavity is provided at the connection between the annular piston rod and the piston assembly, and the oil separation and pressure equalization cavity forms a connecting space for 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 hydraulic cylinder and the third hydraulic cylinder are led out through the pressure-bearing oil supply connecting pipeline opened on the first pressure-bearing heat dissipation valve block.

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

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

[0014] The first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block are both provided with a heat insulation plate, and the heat insulation plate is arranged above the cooling circuit and adjacent to the piston rod end.

[0015] A sintering method for a superhard material grinding wheel homogeneous sintering mold comprises the following steps: a. Film installation (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 the inner mold column on the cushion block, and then place the high-strength spherical pressure-equalizing structure on the upper part of the auxiliary pressure ring; (3) Using an ultrasonic vibrator to evenly vibrate the high-strength spherical pressure-equalizing structure, and using a tool to place the lower split block pressure ring at the bottom of the mold cavity, weighing the powder and evenly placing it in the mold cavity, and using a tool to evenly distribute the abrasive layer; (4) Use the tooling to place the upper split block pressure ring on the powder, place the high-strength spherical pressure equalizing structure and evenly distribute it, and finally place the auxiliary pressure ring on top; b. Hot pressing sintering (5) Place the assembled mold on the working table of the second hydraulic cylinder. First, start the first hydraulic cylinder and the third hydraulic cylinder above and below the mold, and set the pressure P. When the pressure is reached, the first hydraulic cylinder and the third hydraulic cylinder stop working. Under the action of 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, and under the action of the upper and lower second hydraulic cylinders, drive the upper and lower auxiliary pressure rings to move toward each other. The force is transmitted to the high-strength spherical pressure-equalizing mechanism through the auxiliary pressure ring, and the high-strength spherical pressure-equalizing mechanism decomposes the force to the split movable block pressure ring; (7) After the pressing is completed, the piston rods of the upper and lower second hydraulic cylinders are retracted, and then the upper and lower first hydraulic cylinders and the third hydraulic cylinders are started to retract. After reaching the set position, the mold is removed and unloaded to complete the entire process.

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

[0017] The beneficial effects of the present invention are: (1) The present invention discloses a homogeneous sintering mold and sintering method for a superhard material grinding wheel. By "calculusizing" the split live block pressure ring of the sintering mold, a pair of upper and lower split three-rod hydraulic cylinders are used to apply pressure to the upper and lower end surfaces of the mold respectively, and a sintering process with uniform density and uniform heating of the grinding wheel ring is developed, so as to realize the circumferential homogeneous sintering manufacturing of large thickness and narrow ring width grinding wheel rings of metal binder and metal-based composite superhard materials, and solve the series of problems such as 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 binder and metal-based composite grinding wheels.

[0018] (2) The split live-block pressure ring is divided into N evenly distributed live blocks by "calculusization", and the whole pressure ring is decomposed into N evenly distributed live blocks, which is transformed from a single whole ring force-bearing surface into N force-bearing surfaces, to ensure that each force-bearing surface is subjected to consistent force during the pressing process and the pressure transmitted to the powder is consistent; because in the actual implementation process, the weight of the abrasive layer corresponding to each force-bearing surface is different. For the place with smaller weight, the compression amount is larger, and for the place with larger weight, the compression amount is smaller. N evenly distributed live blocks can ensure that the density of the abrasive layer corresponding to each force-bearing surface is consistent; at the same time, 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) Double-cylinder double-end pressing is adopted, and upper and lower hydraulic cylinders are used to apply constant pressure to the outer mold sleeve and inner mold column of the mold, and then the powder is pressurized and sintered. The traditional single-rod hydraulic cylinder at one end is transformed into a three-rod hydraulic cylinder with the same direction. The inner and outer ring cylinder rods are used to fix the outer ring of the mold and arrange the heat sink. The middle ring cylinder rod is mainly used for pressurizing the abrasive layer to ensure close contact between the heat sink and the mold during the sintering process, forming a stable and uniform temperature circulation path. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a traditional hot pressing sintering mold; Figure 2 This is the density distribution diagram of the grinding wheel ring in the traditional way; Figure 3 It is a structural schematic diagram of the movable block equalizing pressure mold of the present invention; Figure 4 It is a structural schematic diagram of a split live block pressure ring; Figure 5 It is a schematic diagram of the pressing process of the movable block equalizing pressing mold of the present invention; Figure 6 It is a simplified structural diagram of a three-rod hydraulic cylinder with the same direction split type; Figure 7 It is a structural diagram of a three-rod hydraulic cylinder with the same direction split type; Figure 8 It is a schematic diagram of the cylinder body of a three-rod hydraulic cylinder with the same direction as the split type; Fig. 9 It is a schematic diagram of bidirectional pressing of a three-rod hydraulic cylinder with the same direction split type; Fig.10 It is a schematic diagram of the pressing process of the same-direction split three-rod hydraulic cylinder; Fig.11 It is the density distribution diagram of the grinding wheel ring obtained by the present invention; Fig.12 The shell crack of the workpiece is obtained by the traditional sintering method; Fig.13 The burrs of workpieces are obtained by traditional sintering method; Fig.14 It is a schematic diagram of the edge of a workpiece obtained by the sintering method of the present invention. DETAILED DESCRIPTION

[0021] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] The present invention provides a superhard material grinding wheel homogeneous sintering mold and a sintering method, such as Figures 3 to 14 shown.

[0023] A superhard material grinding wheel homogenizing sintering mold comprises an outer mold sleeve 1, an inner mold column 2, and a split live block pressure ring 3 and an auxiliary pressure ring 4 arranged in a mold cavity, and the split live 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 surface pressing, and a powder 5 is filled in the mold cavity between the two split live block pressure rings 3; and a high-strength spherical equalizing pressure structure 7 is also provided between the split live block pressure ring 3 and the auxiliary pressure ring 4; the split live block pressure ring 3 comprises N sector blocks and forms a complete cylindrical ring body, and each sector block is movable along the axial direction; during pressing, the upper and lower end surfaces of the mold are pressed respectively by using the same-direction split three-rod hydraulic cylinders arranged in pairs in the upper and lower directions.

[0024] In this embodiment, the outer mold sleeve 1 is a circular cylinder made of graphite or cast iron, and is a mold shape control component. The inner wall of the outer mold sleeve 1 is also sleeved and inlaid with a layer of 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 size of the inner hole of the mold. The outer wall of the inner mold column 2 is inlaid with a layer of high-strength annular low-roughness transition sleeve in a sleeve-joined manner.

[0026] The high-strength annular low-roughness transition sleeve 6 has a thickness of about 5~10mm and is made of silicon carbide or alumina with good high temperature resistance, impact resistance and wear resistance, and the surface roughness reaches below Ra0.4; it can maintain the shape, size and surface roughness during multiple hot pressing sintering, and can effectively reduce the mold wall friction 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-equalizing structure 7 and a split live-block pressure ring 3 are also arranged between the powder 5 and the auxiliary pressure ring 4.

[0028] The high-strength spherical pressure-equalizing structure 7 is composed of high-strength zirconium oxide (silicon carbide, aluminum oxide) fine spheres with different particle diameters (φ0.5~φ5mm); The split movable block pressure ring 3 is composed of N sector blocks to form a complete cylindrical ring body, 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 cylinder structure. During the pressing process, the pressure is transmitted to the high-strength spherical pressure equalizing structure through the auxiliary pressure ring 4, and then the pressure is decomposed and transmitted to the block pressure ring 3 after decomposition. Each block receives equal pressure, and the pressure is pressed on the powder at different positions. 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, the surface quality of the mold in contact with the powder is improved, and the friction between the powder and the mold wall is reduced.

[0030] The specific operation process is as follows: Step 1: Assemble the mold First, assemble the mold, connect 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 pressure-equalizing tissue is placed into the mold cavity and flattened; Secondly, place the split live block pressure ring on the high-strength spherical pressure equalizing structure; Secondly, a certain weight of powder is evenly introduced into the mold cavity and spread flat; Next, place the split live block pressure ring on the split body; Finally, place the auxiliary pressure ring on the split live block pressure ring.

[0031] Step 2: Suppression.

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

[0033] The same-direction split three-rod hydraulic cylinder comprises a first hydraulic cylinder 8, a second hydraulic cylinder 9 and a third hydraulic cylinder 10 which are annularly nested from outside to inside, and a first pressure-bearing heat-dissipating valve block 11 and a second pressure-bearing heat-dissipating valve block 12 respectively arranged at the end of the piston rod of the first hydraulic cylinder and the end of the piston rod of the third hydraulic cylinder, and the liquid inlet and liquid return of the three hydraulic cylinders are independently controlled; 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; The first pressure-bearing heat dissipation valve block 11 and the second pressure-bearing heat dissipation valve block 12 are also provided with cooling circuits for heat dissipation, and the coolants of the two adopt the same branch to ensure the consistent heat conduction of the cooling water inlet and outlet, and then ensure the consistent temperature control rate of the outer mold sleeve and the inner mold column. In order to reduce the cooling water resistance, the cooling circuits are distributed in annular water channels on 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 identically configured and both include a cylinder barrel, an end cover, a piston assembly and an annular piston rod disposed in the cylinder barrel, and an oil inlet and an oil outlet; the piston assembly and the annular piston rod are both annular torus structures. An oil separation and pressure equalization cavity 89 is provided at the connection between the annular piston rod and the piston assembly, and the oil separation and pressure equalization cavity 89 forms a connecting space for the oil cylinders separated by the annular piston rod in 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 connecting pipeline opened on the first pressure-bearing heat dissipation valve block 11 .

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

[0037] The first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block are both provided with a heat insulation plate, and the heat insulation plate is 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 column and the outer mold sleeve of the mold to fix and appropriately pressurize 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 cover, all of which are of conventional type. The third hydraulic cylinder is also provided with a third oil inlet 101 and a fourth oil outlet 104, wherein the fourth oil outlet is led out through a flexible high-pressure oil pipe connected to the end cover assembly and a pressure-bearing oil supply connecting channel 85 on the first pressure-bearing heat dissipating valve block 11.

[0040] Among them, the cylinder barrels of the three hydraulic cylinders share a base, and the oil inlets of the three hydraulic cylinders are arranged on the base; 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 the oil inlet 81 of the first hydraulic cylinder 8 is supplied with hydraulic oil of a certain pressure, the first piston assembly 82 starts 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 liquid inlet 91 of the second hydraulic cylinder 9, the second piston assembly 92 drives the second annular piston rod 93 to move under the action of the hydraulic oil pressure, and drives the pressure block to move upward; The hydraulic oil of a certain pressure is supplied to the liquid inlet 101 of the third hydraulic cylinder 10 , and the third piston assembly 102 drives the third piston rod 103 to move under the action of the hydraulic oil pressure, and drives the second pressure-bearing heat dissipating valve block 12 to move upward.

[0042] In actual work, the first hydraulic cylinder and the third hydraulic cylinder are mainly responsible for giving a certain pressure to the outer mold sleeve and inner mold column of the given mold, and the heat sink is in large-area contact with the outer mold sleeve and the inner mold cavity, ensuring that the thermal conductivity coefficient of the outer mold sleeve, the inner mold cavity and the heat sink is consistent with the thermal conductivity coefficient of the auxiliary pressure ring and the heat sink during the sintering process; the second hydraulic cylinder is mainly responsible for providing pressing pressure for the auxiliary pressure ring for actual pressing work.

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

[0044] a. Film installation According to the design, the height H of the powder after mold installation is calculated. At the same time, the height H1 of the split live block pressure ring, the high-strength spherical pressure-equalizing structure H2, and the outer mold sleeve H4 are 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. The height H3 of the T-type pressure ring of the corresponding size 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 the inner mold column on the cushion block, and then place the high-strength spherical pressure-equalizing structure on the upper part of the lower T-shaped pressure ring; (3) An ultrasonic vibrator is used to evenly vibrate the high-strength spherical pressure-equalizing structure, and a tool is used to place the lower split block pressure ring at the bottom of the mold cavity, a certain weight of powder is weighed and evenly placed in the mold cavity, and a tool is used to evenly distribute the abrasive layer; (4) Use the tooling to place the upper split block pressure ring on the powder, place a certain amount of high-strength spherical pressure-equalizing structure and distribute it evenly, and finally place the auxiliary pressure ring on top; b. Hot pressing sintering (5) Place the assembled mold on the working table of the second hydraulic cylinder, and use the same-direction split three-rod hydraulic cylinders in pairs to avoid the problem of inconsistent movement of the upper and lower pressure rings during unidirectional pressure application.

[0046] First, start the first hydraulic cylinder 8 and the third hydraulic cylinder 10 above and below the mold, and set the pressure P. When the pressure reaches the required value, the first hydraulic cylinder 8 and the third hydraulic cylinder 10 stop working, and the pressure is converted into the force F.g1 、F g1 '、 / F g3 、F g3 ', under the action of 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 a two-way self-locking valve 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 exert force F g2 、F g2 'The upper and lower auxiliary pressure rings 4 are driven to move toward each other under the action, and the force is transmitted to the high-strength spherical pressure-equalizing organization through the auxiliary pressure ring, and the high-strength spherical pressure-equalizing organization decomposes the force to the split live block pressure ring; Each split live block pressure ring transmits pressure to the corresponding powder below. Due to the difference in weight and volume, the compression amount of each local powder changes 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. At the same time, the heat is conducted and adjusted by the upper and lower first pressure-bearing heat dissipation valve blocks and the second pressure-bearing heat dissipation valve blocks, so that the temperature rise and fall process and rate inside the powder are consistent with the theoretical design, and finally a grinding wheel ring with uniform density and consistent organizational structure is formed.

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

[0049] The following is further described in conjunction with specific embodiments: A superhard material grinding wheel homogeneous sintering mold and a sintering method disclosed in the present invention are used to press a grinding wheel ring with a metal-resin composite binder having an outer diameter of φ300 mm, a thickness of 60 mm, and a wall thickness of 5 mm.

[0050] In order to test the effect, the method of the present invention is used to press the grinding wheel ring and carry out a hardness test. At the same time, in order to accurately measure the hardness, no superhard material is added to the test powder. The designed weight is 3.8 kg of powder (without superhard material). The split live block pressure ring is divided into 72 equal blocks. The high-strength spherical equalizing structure is composed of zirconia balls with average diameters of φ0.5 mm and φ0.2 mm in a ratio of 1:2.

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

[0052] A special hardness tester is used to test the hardness of the end face of the grinding wheel ring. The measured data compared with the traditional pressing method are shown in Table 1, and the density distribution is shown in Table 1. Fig.11 .

[0053] Table 1. Comparison of grinding wheel ring end surface hardness In addition, the method of the present invention is used to make a metal-resin composite bond superhard material grinding wheel with a diameter of φ202mm, a ring width of 4mm, a thickness of 20mm and a diamond grain size of 800#, and the silicon carbide wafer is ground. At the same time, compared with the traditional sintering method (such as Fig.12 and Fig.13 The grinding effect is shown in Figure 2. It can be seen that the chipping is significantly improved, the shell cracks are eliminated, and the grinding stability is improved ( Fig.14 ).

[0054] If the words "first", "second" and the like are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and the above words have no special meaning.

[0055] The above shows and describes 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 above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the invention claimed for protection. The scope of protection claimed for the present invention is defined by the attached claims and their equivalents.

[0056] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. A superhard material grinding wheel homogeneous sintering mold, characterized in that: It includes an outer mold sleeve, an inner mold column, and a split live block pressure ring and an auxiliary pressure ring arranged in the mold cavity, and the split live 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 surface pressing, and the powder is filled in the mold cavity between the two split live block pressure rings; A high-strength spherical pressure-equalizing structure is provided between the split live block pressure ring and the auxiliary pressure ring; The split movable block pressure ring includes N sector blocks forming a complete cylindrical ring body, and each sector block is movable along the axial direction; During pressing, the upper and lower end surfaces of the mold are pressed respectively by using the same-direction split three-rod hydraulic cylinders arranged in pairs up and down.

2. A superhard material grinding wheel homogeneous sintering mold according to claim 1, characterized in that: The same-direction split three-rod hydraulic cylinder comprises a first hydraulic cylinder, a second hydraulic cylinder and a third hydraulic cylinder which are annularly nested in sequence from outside to inside, and a first pressure-bearing heat-dissipating valve block correspondingly arranged at the end of the piston rod of the first hydraulic cylinder and a second pressure-bearing heat-dissipating valve block arranged at the end of the piston rod of the third hydraulic cylinder, and the liquid inlet and liquid return of the three hydraulic cylinders are independently controlled; The first hydraulic cylinder is used to press the outer mold sleeve, the second hydraulic cylinder is used to press the auxiliary pressure ring, and the third hydraulic cylinder is used to press the inner mold column; The first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block are both provided with cooling circuits for heat dissipation, and the cooling fluids of the two are in the same branch.

3. A superhard material grinding wheel homogeneous sintering mold according to claim 2, characterized in that: The first hydraulic cylinder and the second hydraulic cylinder are identically configured and both include a cylinder barrel, a piston assembly and an annular piston rod disposed in the cylinder barrel, and an oil inlet and an oil outlet; An oil separation and pressure equalization cavity is provided at the connection between the annular piston rod and the piston assembly, and the oil separation and pressure equalization cavity forms a connecting space for the oil cylinders separated by the annular piston rod in the cylinder barrel.

4. A superhard material grinding wheel homogeneous sintering mold according to claim 3, characterized in that: The high-pressure oil pipes connected to the oil outlets of the second hydraulic cylinder and the third hydraulic cylinder are led out through the pressure-bearing oil supply connecting pipeline opened on the first pressure-bearing heat dissipation valve block.

5. The homogeneous sintering mold for superhard material grinding wheel according to claim 2, characterized in that: The cooling circuit is distributed in the form of annular water channels on both the first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block.

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

7. The homogeneous sintering mold for superhard material grinding wheel according to claim 1, characterized in that: The first pressure-bearing heat dissipation valve block and the second pressure-bearing heat dissipation valve block are both provided with a heat insulation plate, and the heat insulation plate is arranged above the cooling circuit and adjacent to the piston rod end.

8. A sintering method for a homogeneous sintering mold of a superhard material grinding wheel according to any one of claims 1 to 7, characterized in that: The following steps are involved: a. Film installation (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 the inner mold column on the cushion block, and then place the high-strength spherical pressure-equalizing structure on the upper part of the auxiliary pressure ring; (3) Using an ultrasonic vibrator to evenly vibrate the high-strength spherical pressure-equalizing structure, and using a tool to place the lower split block pressure ring at the bottom of the mold cavity, weighing the powder and evenly placing it in the mold cavity, and using a tool to evenly distribute the abrasive layer; (4) Use the tooling to place the upper split block pressure ring on the powder, place the high-strength spherical pressure equalizing structure and evenly distribute it, and finally place the auxiliary pressure ring on top; b. Hot pressing sintering (5) Place the assembled mold on the working table of the second hydraulic cylinder. First, start the first hydraulic cylinder and the third hydraulic cylinder above and below the mold, and set the pressure P. When the pressure is reached, the first hydraulic cylinder and the third hydraulic cylinder stop working. Under the action of 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, and under the action of the upper and lower second hydraulic cylinders, drive the upper and lower auxiliary pressure rings to move toward each other. The force is transmitted to the high-strength spherical pressure-equalizing mechanism through the auxiliary pressure ring, and the high-strength spherical pressure-equalizing mechanism decomposes the force to the split movable block pressure ring; (7) After the pressing is completed, the piston rods of the upper and lower second hydraulic cylinders are retracted, and then the upper and lower first hydraulic cylinders and the third hydraulic cylinders are started to retract. After reaching the set position, the mold is removed and unloaded to complete the entire process.

9. A superhard material grinding wheel homogeneous sintering mold and sintering method according to claim 8, characterized in that: In step (5), both the first hydraulic cylinder and the third hydraulic cylinder are locked by a two-way self-locking valve.

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