A cold-pressing forming device and process for preparing a stepped composite diamond scribe

Abstract

The present application belongs to the technical field of cold press forming equipment, and particularly relates to a cold press forming device and process for preparing a stepped composite diamond dicing sheet, comprising a hydraulic press body and a hydraulic workbench, and an L-shaped rack is fixedly sleeved with the outer wall of the hydraulic press body. The cold press forming device can realize the functions of down pressure torsion mixing of powder, air extraction during the forming process, pressure maintaining bidirectional pressurization, and automatic material pushing and discharging, effectively solves the problems of poor bridging and filling of thin blade type cavity powder, stress concentration of steps, cavity gas accumulation, and large density gradient of one-way pressing in the cold press forming of the stepped composite diamond dicing sheet, and further effectively improves the uniformity of the green density of each layer of the stepped composite diamond dicing sheet, reduces the defects of green body micro-cracks and edge collapse of the stepped composite diamond dicing sheet, improves the qualified rate of the formed green body, reduces production loss, improves the reliability of the cold press forming device, and meets the large-scale production demand of high-precision stepped composite diamond dicing sheets.

Description

Technical Field

[0001] This invention belongs to the technical field of cold pressing equipment, and in particular relates to a cold pressing device and process for preparing stepped composite diamond wafers. Background Technology

[0002] Stepped composite diamond dicing blades are core superhard cutting tools for precision cutting of hard and brittle materials such as semiconductor wafers and precision optical glass. They are mainly composed of a rigid support matrix and a radially stepped diamond working layer. The diamond working layer has a stepped thickness increasing structure from the outer edge to the matrix, which has higher cutting accuracy and structural rigidity than ordinary uniform thickness dicing blades. Cold pressing is the core pre-process for the preparation of this type of dicing blade. Diamond micro powder and metal binder powder are compacted and bonded to the outer edge of the matrix by room temperature static pressure. The formed green blank has a fixed stepped contour and basic structural strength, which can provide a qualified blank for subsequent vacuum sintering and precision shaping processes. It is a key process to ensure the integrity of the stepped structure and the consistency of the finished product performance of the stepped dicing blade. Therefore, high-precision cold pressing equipment has become the core equipment for the mass production of stepped composite diamond dicing blades.

[0003] Currently, most traditional cold pressing equipment uses a fixed mold and pure axial unidirectional extrusion. This method can only achieve simple static pressure forming. It has significant limitations in adapting to special cavity structures with abrupt changes in thickness of stepped diced pieces and also suffers from serious forming defects.

[0004] This is because traditional forming methods cannot improve the flowability of powder in stepped cavities. Thin-bladed, narrow-cavity cavities are prone to problems such as powder bridging, uneven filling, and gas accumulation in the cavity. This results in large differences in density gradients of each step in the green blank and poor powder bonding. At the same time, single axial extrusion easily causes stress concentration at the right-angle steps of the steps, leading to problems such as micro-cracks inside the green blank and edge chipping. These problems not only directly reduce the forming accuracy and structural strength of stepped composite diamond dicing green blanks, but also amplify defects such as dimensional deviations and insufficient interlayer bonding after sintering. Ultimately, this leads to poor cutting stability of the finished product and easy chipping and detachment of the blade. This not only affects the pass rate of cold pressing of stepped composite diamond dicing green blanks, but also affects the reliability of stepped composite diamond dicing green blanks in use, significantly increasing the production loss and manufacturing cost of stepped dicing green blanks, and seriously restricting the large-scale, high-quality production of high-precision stepped composite diamond dicing green blanks.

[0005] To address these issues, we propose a cold pressing apparatus and process for preparing stepped composite diamond wafers. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a cold pressing molding apparatus and process for preparing stepped composite diamond wafers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a cold pressing forming device for preparing stepped composite diamond dicing sheets, comprising a hydraulic press body and a hydraulic worktable, wherein an L-shaped frame is fixedly sleeved on the outer wall of the hydraulic press body, the bottom end of the L-shaped frame is fixedly connected to the upper surface of the hydraulic worktable, an outer mold and an inner mold for cold pressing forming are fixedly connected to the upper surface of the hydraulic worktable, and a bottom mold and a stepped pressing mold for cold pressing forming are movably sleeved on the outer wall of the inner mold, wherein the outer walls of the bottom mold and the stepped pressing mold are in sliding contact with the inner wall of the outer mold;

[0008] The moving end of the hydraulic press body is fixedly connected to a torsion mechanism for twisting the stepped mold.

[0009] The upper surface of the hydraulic worktable is fixedly connected to a drive mechanism that controls the torsion of the twisting mechanism.

[0010] The four support legs of the hydraulic workbench are all fixedly connected to the outer walls of the material-lifting mechanism.

[0011] The upper surface of the L-shaped frame is provided with a through hole, and an air extraction mechanism is fixedly connected to the wall of the through hole.

[0012] In the aforementioned cold pressing molding apparatus for preparing stepped composite diamond dicings, the torsion mechanism includes a U-shaped frame fixedly connected to the moving end of the hydraulic press body. A hollow shell is fixedly connected to the bottom end of the U-shaped frame. Connecting bearings are fixedly connected to both the top and bottom ends of the hollow shell. Fixing holes that mate with the outer wall of the outer ring of the connecting bearings are opened at both the top and bottom ends of the hollow shell. A connecting cylinder is fixedly connected to the inner walls of the two connecting bearings. The bottom end of the connecting cylinder is fixedly connected to the upper surface of the stepped die. A gear is fixedly sleeved on the outer wall of the connecting cylinder. A circular hole is opened on the side wall of the hollow shell, and a first hydraulic cylinder is fixedly connected to the wall of the circular hole. A rack that meshes with the side wall of the gear is fixedly connected to the moving end of the first hydraulic cylinder. An installation hole is opened at the bottom end of the hollow shell, and a pressure sensor that mates with the top end of the outer die is fixedly connected to the wall of the installation hole.

[0013] In the above-mentioned cold pressing molding device for preparing stepped composite diamond dicing, the inner wall of the top end of the connecting cylinder is fixedly connected with an extrusion limiting block that cooperates with the top end of the inner mold.

[0014] In the above-mentioned cold pressing forming device for preparing stepped composite diamond dicing, the first cylinder includes a cylinder housing. A through hole is provided on the side wall of the cylinder housing, and a moving rod is movably connected to the wall of the through hole. The outer side of the moving rod is fixedly connected to the side wall of the rack. A limit block is fixedly connected to the end of the moving rod away from the rack. A sealing ring is fixedly sleeved on the outer wall of the limit block. Both the outer wall of the limit block and the outer wall of the sealing ring are in sliding contact with the inner wall of the cylinder housing.

[0015] In the aforementioned cold pressing forming apparatus for preparing stepped composite diamond dicing sheets, the driving mechanism includes a hydraulic cylinder fixedly connected to the upper surface of a hydraulic worktable. A sealing piston is slidably connected to the inner wall of the hydraulic cylinder. An electric push rod is fixedly embedded at the top of the hydraulic cylinder. The moving end of the electric push rod is fixedly connected to the upper surface of the sealing piston. A fixing hole that mates with the electric push rod is opened at the top of the L-shaped frame. A three-way reversing solenoid valve is fixedly connected to the bottom of the hydraulic cylinder. A first oil pipe is fixedly connected to the top outlet of the three-way reversing solenoid valve. The connecting end of the first oil pipe is fixedly connected to the oil nozzle of the first oil cylinder. A second oil pipe is fixedly connected to the side outlet of the three-way reversing solenoid valve. The connecting end of the second oil pipe passes through the bottom of the hydraulic worktable.

[0016] In the aforementioned cold pressing molding device for preparing stepped composite diamond wafers, the ejector mechanism includes a support plate fixedly connected to the outer wall of the four support legs of the hydraulic worktable. The upper surface of the support plate has a through hole, and the wall of the through hole is fixedly connected to a second hydraulic cylinder with the same structure as the first hydraulic cylinder. The connecting end of the second oil pipe is fixedly connected to the oil nozzle of the second hydraulic cylinder. The moving end of the second hydraulic cylinder is fixedly connected to a U-shaped top block. The upper surface of the hydraulic worktable has two connecting through holes for the movement of the two vertical parts of the U-shaped top block. The top ends of the two vertical parts of the U-shaped top block are fixedly connected to the lower surface of the bottom mold. The upper surface of the bottom mold has multiple vent holes, and the wall of the vent holes is fixedly connected to a ceramic vent block. The lower surface of the bottom mold is fixedly connected to multiple limiting support blocks.

[0017] In the aforementioned cold pressing forming apparatus for preparing stepped composite diamond dicings, the air extraction mechanism includes an air extraction cylinder fixedly embedded at the top of an L-shaped frame. The bottom end of the air extraction rod of the air extraction cylinder is fixedly connected to the upper surface of a hollow shell. The air nozzle of the air extraction cylinder is fixedly connected to an air pipe. The connecting end of the air pipe is fixedly connected to a sealing cylinder. The top end of the sealing cylinder is fixedly connected to the outer wall of a hydraulic worktable. The bottom end of the sealing cylinder is fixedly connected to the upper surface of a support plate. The second hydraulic cylinder is located inside the sealing cylinder.

[0018] In the above-mentioned cold pressing forming device for preparing stepped composite diamond dicing, a PLC controller is fixedly connected to the upper surface of the support plate, and a touch panel is fixedly connected to the upper surface of the hydraulic worktable.

[0019] A cold pressing process for preparing stepped composite diamond dicing wafers, which employs the aforementioned cold pressing apparatus for preparing stepped composite diamond dicing wafers, includes the following steps:

[0020] S1, Parameter preset: Input process parameters into the PLC controller via the touch panel, and preset the stepped die torsion angle, pressure holding time, and hydraulic actuator action sequence;

[0021] S2. Loading and positioning: The support matrix of the stepped composite diamond dicing is fitted onto the outer wall of the inner mold and placed on the upper surface of the bottom mold to complete the positioning. A certain amount of raw material powder mixed with diamond and metal binder is put into the forming cavity between the outer mold and the inner mold.

[0022] S3, Downward Torsional Extrusion: The starting device moves the hydraulic press body downward, driving the torsion mechanism and the stepped die into the forming cavity. The drive mechanism drives the torsion mechanism, causing the stepped die to reciprocate and twist synchronously during the downward pressing process, applying axial extrusion and shearing action to the powder inside the cavity.

[0023] S4. Synchronous air extraction and degassing: While the raw material powder is being extruded by the step die, the air extraction mechanism works simultaneously to extract the air trapped in the dead corners of the molding cavity and the thin blade gaps by using the ceramic permeable block on the bottom mold, and to discharge the gas inside the molding cavity.

[0024] S5. Pressure signal triggers pressure holding: When the stepped die is pressed down to the position, the pressure sensor contacts the top of the outer die and sends a pressure signal to the PLC controller. The PLC controller controls the three-way reversing solenoid valve to reverse, and hydraulic oil is input into the second cylinder, driving the bottom die to rise slightly, forming bidirectional pressure with the stepped die that is kept in the pressed state. At the same time, the torsion action of the torsion mechanism stops, and the pressure holding stage begins.

[0025] S6. Pressure holding molding: Maintain bidirectional pressure and hold pressure for a preset time to complete the dense molding of the stepped composite diamond diced green blank;

[0026] S7. Press mold return lifting: After the pressure holding is completed, the PLC controller controls the moving end of the hydraulic press body to retract upward, driving the stepped press mold to lift and disengage from the forming cavity;

[0027] S8. Material removal: The second hydraulic cylinder continues to lift, and the bottom mold is pushed by the U-shaped top block to push the formed dicing blank out of the outer mold cavity, and the formed stepped composite diamond dicing blank is taken out.

[0028] Compared with existing technologies, the advantages of this invention are:

[0029] 1. Through the established torsion and drive mechanisms, when the hydraulic press body drives the stepped die to extrude the raw material powder, a mixture of diamond and metal binder, into the molding cavity, the electric push rod of the drive mechanism reciprocates, pushing hydraulic oil through the oil circuit to the first cylinder. The first cylinder drives the rack and pinion transmission pair, causing the connecting cylinder and the stepped die to reciprocate at a small angle during the downward pressing process. The connecting bearing decouples the die torsion from the axial downward pressing motion, ensuring that the axial extrusion force is not disturbed by the torsional action. This structure changes the traditional fixed die's simple axial static pressure mode, specifically addressing the stepped die's... The abrupt thickness variation in the cavity of the ladder-shaped composite diamond dicing molding process utilizes the powder shearing and misalignment effect brought about by synchronous downward torsion to break the powder bridging phenomenon in the thin-edged area. This promotes the full filling of powder into each step layer, solving the industry problem of large radial density differences and insufficient powder particle bonding in the stepped cavity. It also alleviates stress concentration at the step corners, reduces the generation of microcracks inside the green blank, effectively improves the structural strength of the green blank, reduces the incidence of edge chipping and local cracking during the demolding stage, improves the forming qualification rate of cold-pressed green blanks, and enhances the reliability of cold-pressing equipment.

[0030] 2. Through the set air extraction mechanism, when the hydraulic press body drives the torsion mechanism and the stepped die to feed and extrude the raw material powder downwards, the pull rod of the air extraction cylinder moves synchronously with the hollow shell. Through the air pipe, the sealing cylinder, and then through the ceramic permeable block of the bottom mold, the air trapped in the dead corner of the step and the thin blade gap of the forming cavity is continuously extracted outwards. In view of the problem that the gas is difficult to expel in the sealed dead corner of the stepped cavity in traditional cold pressing, which easily forms pores and local material shortages, this structure can expel the gas trapped in the cavity in time before the powder is compacted, avoid the gas being trapped in the green body and forming pore defects, further improve the overall density of the raw material powder after compaction, prevent the pores inside the stepped composite diamond dicing green body from being further enlarged in the subsequent vacuum sintering process, avoid derivative problems such as porosity, insufficient local strength, and easy chipping and detachment of the finished product after sintering, and ensure the reliability of the subsequent finished products of stepped composite diamond dicing.

[0031] 3. Through the installation of pressure sensors, three-way reversing solenoid valves, and ejector mechanisms, when the stepped die is pressed down to its final position, the pressure sensor contacts the top of the outer die and feeds back a pressure signal. The PLC controller then controls the three-way reversing solenoid valve to switch the hydraulic circuit, inputting hydraulic oil into the second cylinder. This drives the U-shaped top block to slightly raise the bottom die, creating a bidirectional pressurization process with the stepped die maintaining its downward position. Furthermore, during the pressure holding phase, the torsion action of the torsion mechanism is stopped. This overcomes the shortcomings of traditional unidirectional axial pressing, where pressure attenuates axially, causing inconsistent density across different stepped layers. The bidirectional pressurization further... The density difference between each step of the green blank is reduced, and the torsion action is stopped during the holding pressure stage to avoid shearing action from damaging the right-angled step contour of the green blank. This ensures the dimensional accuracy of the step structure of the step-shaped composite diamond dicing green blank. After the holding pressure is completed, the green blank is ejected by the ejector mechanism. This realizes the automated linkage of forming, holding pressure and demolding, reduces manual intervention and reduces dimensional deviation caused by human operation. It can provide high-quality step-shaped composite diamond dicing green blanks with complete contours and uniform density for subsequent sintering processes, meeting the needs of large-scale production of high-precision step-shaped composite diamond dicing. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the cold pressing forming device and process for preparing stepped composite diamond wafers provided by the present invention.

[0033] Figure 2 yes Figure 1 A schematic diagram of the structure in partial cross-section;

[0034] Figure 3 yes Figure 2 A schematic diagram of the structure of the first hydraulic cylinder;

[0035] Figure 4 yes Figure 2 Schematic diagram of the torsion mechanism;

[0036] Figure 5 yes Figure 2 Enlarged structural diagram of the central top material mechanism;

[0037] Figure 6 yes Figure 2 A top-view schematic diagram of the meshing of the gear and rack.

[0038] In the diagram: 1. Hydraulic press body; 2. Hydraulic worktable; 3. L-shaped frame; 4. Outer mold; 5. Torsion mechanism; 51. U-shaped frame; 52. Hollow shell; 53. Connecting bearing; 54. Connecting cylinder; 55. Gear; 56. Rack; 57. Pressure sensor; 6. First cylinder; 61. Cylinder housing; 62. Moving rod; 63. Limit block; 64. Sealing ring; 7. Drive mechanism; 71. Hydraulic cylinder; 72. Sealing piston; 73. Electric push rod; 7 4. Three-way reversing solenoid valve; 75. First oil pipe; 76. Second oil pipe; 8. Ejector mechanism; 81. Support plate; 82. Second oil cylinder; 83. U-shaped top block; 84. Connecting through hole; 85. Ceramic vent block; 86. Limiting support block; 9. Air extraction mechanism; 91. Air extraction cylinder; 92. Air pipe; 93. Sealing cylinder; 10. Inner mold; 11. Stepped mold; 12. Bottom mold; 13. Extrusion limiting block; 14. PLC controller; 15. Touch panel. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] like Figures 1-6 As shown, a cold pressing forming apparatus for preparing stepped composite diamond dicings includes a hydraulic press body 1 and a hydraulic worktable 2. An L-shaped frame 3 is fixedly sleeved on the outer wall of the hydraulic press body 1. The bottom end of the L-shaped frame 3 is fixedly connected to the upper surface of the hydraulic worktable 2. An outer mold 4 and an inner mold 10 for cold pressing forming are fixedly connected to the upper surface of the hydraulic worktable 2. A bottom mold 12 and a stepped pressing mold 11 for cold pressing forming are movably sleeved on the outer wall of the inner mold 10. The outer walls of 11 are in sliding contact with the inner wall of the outer mold 4. The outer mold 4, inner mold 10, bottom mold 12 and stepped mold 11 are set together to form a stepped forming cavity that is adapted to the stepped composite diamond dicing. Unlike the flat cavity of ordinary equal-thickness dicing, this cavity matches the stepped contour of the diamond working layer with the thickness increasing from the outer edge to the matrix, providing a forming basis for the stepped green blank, avoiding the mismatch between the forming contour and the product structure, and ensuring that the stepped green blank that meets the design requirements is obtained after forming.

[0041] The moving end of the hydraulic press body 1 is fixedly connected to a torsion mechanism 5 for torsion of the stepped die 11. The torsion mechanism 5 includes a U-shaped frame 51 fixedly connected to the moving end of the hydraulic press body 1. A hollow shell 52 is fixedly connected to the bottom end of the U-shaped frame 51. A connecting bearing 53 is fixedly connected to both the top and bottom ends of the hollow shell 52. A fixing hole that matches the outer wall of the outer ring of the connecting bearing 53 is opened at both the top and bottom ends of the hollow shell 52. A connecting cylinder 54 is fixedly connected to the inner wall of the two connecting bearings 53. The connecting bearings 53 decouple the downward linear motion and the circumferential torsion motion. That is, the hollow shell 52 and the U-shaped frame 51 are axially fed with the hydraulic press body 1, while the connecting cylinder 54 can rotate independently in the circumferential direction relative to the hollow shell 52. This transmits the downward pressing force without transmitting the torsion motion to the hydraulic press body 1, thus solving the problem of motion interference when the stepped die 11 is pressed down and twisted at the same time.

[0042] The bottom end of the connecting cylinder 54 is fixedly connected to the upper surface of the stepped mold 11. A gear 55 is fixedly sleeved on the outer wall of the connecting cylinder 54. A circular hole is opened on the side wall of the hollow shell 52, and a first oil cylinder 6 is fixedly connected to the hole wall. A rack 56 that meshes with the side wall of the gear 55 is fixedly connected to the moving end of the first oil cylinder 6. An installation hole is opened at the bottom end of the hollow shell 52, and a pressure sensor 57 that cooperates with the top of the outer mold 4 is fixedly connected to the hole wall of the installation hole. This torsion mechanism 5, while axially compressing, gives the stepped mold 11 a small-angle shearing torsion, which drives the raw material powder inside the molding cavity to undergo shearing and displacement, breaks the thin blade narrow cavity powder bridging, and promotes the raw material powder to fully flow and fill each step level, improves the mechanical interlocking degree between raw material powder particles, improves the radial density gradient, alleviates the stress concentration at the step corner, reduces the micro-cracks inside the stepped composite diamond diced blank, improves the strength of the stepped composite diamond diced blank, and reduces the risk of demolding edge chipping.

[0043] The first hydraulic cylinder 6 includes a cylinder housing 61. A through hole is provided on the side wall of the cylinder housing 61, and a movable rod 62 is movably connected to the wall of the through hole. The outer side of the movable rod 62 is fixedly connected to the side wall of the rack 56. A limit block 63 is fixedly connected to the end of the movable rod 62 away from the rack 56. A sealing ring 64 is fixedly sleeved on the outer wall of the limit block 63. Both the outer wall of the limit block 63 and the outer wall of the sealing ring 64 slide in contact with the inner wall of the cylinder housing 61. The sealing ring 64 cooperates with the limit block 63 to achieve high-pressure oil sealing inside the cylinder housing 61, preventing oil leakage and insufficient driving force of the rack 56.

[0044] A drive mechanism 7 for controlling the torsion of the twisting mechanism 5 is fixedly connected to the upper surface of the hydraulic worktable 2. The drive mechanism 7 includes a hydraulic cylinder 71 fixedly connected to the upper surface of the hydraulic worktable 2. A sealing piston 72 is slidably connected to the inner wall of the hydraulic cylinder 71. An electric push rod 73 is fixedly embedded at the top of the hydraulic cylinder 71. The moving end of the electric push rod 73 is fixedly connected to the upper surface of the sealing piston 72. A fixing hole for cooperating with the electric push rod 73 is opened at the top of the L-shaped frame 3. A three-way reversing solenoid valve 74 is fixedly connected to the bottom end of the hydraulic cylinder 71. A first oil pipe 75 is fixedly connected to the top outlet of the three-way reversing solenoid valve 74. The connecting end of the first oil pipe 75 is fixedly connected to the oil nozzle of the first oil cylinder 6. The side outlet of the three-way reversing solenoid valve 74 is fixedly connected to... A second oil pipe 76 is connected, with its connecting end passing through the bottom of the hydraulic worktable 2. Both the first oil pipe 75 and the second oil pipe 76 are high-pressure flexible oil pipes. The electric push rod 73 drives the sealed piston 72 to reciprocate, converting the mechanical thrust into hydraulic oil pressure. The oil circuit is switched through the three-way reversing solenoid valve 74: the forward passage supplies oil to the first cylinder 6 through the first oil pipe 75, realizing the reciprocating rotation of the torsion mechanism 5; after reversing, the hydraulic oil is transported to the top material mechanism 8 through the second oil pipe 76. A set of power sources provides hydraulic power to the torsion mechanism 5 and the top material mechanism 8 respectively. The three-way reversing solenoid valve 74 receives the electrical signal from the PLC controller 14 to complete the oil circuit switching, realizing the automatic switching of the timing of downward torsion, pressure holding and top material, and improving process consistency.

[0045] The four support legs of the hydraulic worktable 2 are all fixedly connected to the outer walls of a material-lifting mechanism 8. The material-lifting mechanism 8 includes a support plate 81 fixedly connected to the outer walls of the four support legs of the hydraulic worktable 2. A through hole is provided on the upper surface of the support plate 81, and a second cylinder 82 with the same structure as the first cylinder 6 is fixedly connected to the wall of the through hole. The connecting end of the second oil pipe 76 is fixedly connected to the oil nozzle of the second cylinder 82. A U-shaped top block 83 is fixedly connected to the moving end of the second cylinder 82. Two connecting through holes 84 are provided on the upper surface of the hydraulic worktable 2 for the movement of the two vertical parts of the U-shaped top block 83. The top ends of the two vertical parts of the U-shaped top block 83 are fixedly connected to the lower surface of the bottom mold 12. Multiple vent holes are provided on the upper surface of the bottom mold 12, and the walls of the vent holes are fixedly connected to the upper surface of the bottom mold 12. A ceramic permeable block 85 is fixedly connected, which allows gas to pass through while blocking the leakage of raw material powder. Multiple limiting support blocks 86 are fixedly connected to the lower surface of the bottom mold 12. The second oil cylinder 82 receives hydraulic oil from the second oil pipe 76 to drive the U-shaped top block 83 to rise and fall. The U-shaped top block 83 pushes the bottom mold 12 to move up and down. During the pressure holding stage, the bottom mold 12 is slightly raised, forming bidirectional pressure with the stepped mold 11 which is kept under pressure. This solves the problem of the traditional single axial extrusion pressure decreasing along the thickness direction, causing inconsistent density of each stepped layer. It further reduces the density difference between different stepped layers and improves the density and uniformity of the stepped composite diamond diced green blank. After molding, it continues to rise to achieve the demolding of the stepped composite diamond diced green blank.

[0046] The upper surface of the L-shaped frame 3 has a through hole, and the wall of the through hole is fixedly connected to an air extraction mechanism 9. The air extraction mechanism 9 includes an air extraction cylinder 91 fixedly embedded at the top of the L-shaped frame 3. The bottom end of the air extraction rod of the air extraction cylinder 91 is fixedly connected to the upper surface of the hollow shell 52. The air nozzle of the air extraction cylinder 91 is fixedly connected to an air pipe 92. The connecting end of the air pipe 92 is fixedly connected to a sealing cylinder 93. The top end of the sealing cylinder 93 is fixedly connected to the outer wall of the hydraulic worktable 2. The bottom end of the sealing cylinder 93 is fixedly connected to the upper surface of the support plate 81. The second oil cylinder 82 is located inside the sealing cylinder 93. During the extrusion of the raw material powder, the air extraction mechanism 9 simultaneously extracts the air trapped in the forming cavity, eliminates air hole defects, prevents air holes from remaining in the sintering process, and avoids defects such as large pores, insufficient bonding strength, and easy chipping and detachment of the dicing after sintering. The sealing cylinder 93 surrounds the second oil cylinder 82, which not only protects the second oil cylinder 82 from powder contamination, but also constructs a closed air extraction channel to improve the air extraction efficiency.

[0047] The inner wall of the top end of the connecting cylinder 54 is fixedly connected to a compression limiting block 13 that cooperates with the top end of the inner mold 10. The compression limiting block 13 can press against the top end of the inner mold 10 when it is pressed down over the stroke, and mechanically limit the connecting cylinder 54 and the stepped mold 11 to prevent the hydraulic press body 1 from pressing the base and mold over the stroke, thus playing a role in mechanical overload protection and improving the safety of equipment operation.

[0048] A PLC controller 14 is fixedly connected to the upper surface of the support plate 81, and a touch panel 15 is fixedly connected to the upper surface of the hydraulic worktable 2. The PLC controller 14 receives the process parameters input by the touch panel 15 and the feedback signal from the pressure sensor 57, and uniformly controls the timing of the electric push rod 73 and the three-way reversing solenoid valve 74. This enables the torsion angle, pressure holding time, and timing of each cylinder's action to be editable, adapting to the production of stepped composite diamond wafers of different specifications, reducing human error, and improving the consistency of molding quality of different batches of products. Moreover, the above-mentioned electrical components and electrical connections are all existing technologies and will not be described in detail here.

[0049] A cold pressing process for preparing stepped composite diamond dicing wafers, which employs the aforementioned cold pressing apparatus for preparing stepped composite diamond dicing wafers, includes the following steps:

[0050] S1, parameter preset: Input process parameters to PLC controller 14 via touch panel 15, preset the torsion angle of stepped die 11, pressure holding time, and hydraulic actuator action sequence.

[0051] S2, Loading and Positioning: The support base of the stepped composite diamond dicing is fitted onto the outer wall of the inner mold 10 and placed on the upper surface of the bottom mold 12 to complete the positioning. A certain amount of raw material powder mixed with diamond and metal binder is put into the forming cavity between the outer mold 4 and the inner mold 10.

[0052] S3, Downward Torsional Extrusion: The starting device moves the hydraulic press body 1 downward, driving the torsion mechanism 5 and the stepped die 11 into the forming cavity. The drive mechanism 7 drives the torsion mechanism 5, causing the stepped die 11 to reciprocate and twist synchronously during the downward pressing process, applying axial extrusion and shearing action to the powder inside the cavity.

[0053] S4. Synchronous air extraction and degassing: While the stepped die 11 is pressing the raw material powder downwards, the air extraction mechanism 9 works simultaneously, using the ceramic permeable block 85 on the bottom die 12 to extract the air trapped in the dead corners of the molding cavity steps and the thin blade gaps, and to discharge the gas inside the molding cavity.

[0054] S5, Pressure signal triggers pressure holding: When the stepped die 11 is pressed down to the position, the pressure sensor 57 contacts the top of the outer die 4 and sends a pressure signal to the PLC controller 14. The PLC controller 14 controls the three-way reversing solenoid valve 74 to reverse, and hydraulic oil is input into the second oil cylinder 82, driving the bottom die 12 to rise slightly, forming bidirectional pressure with the stepped die 11 which is in a pressed state. At the same time, the torsion action of the torsion mechanism 5 is stopped, and the pressure holding stage is entered.

[0055] S6. Pressure holding molding: Maintain bidirectional pressure and hold pressure for a preset time to complete the dense molding of the stepped composite diamond diced green blank;

[0056] S7. Press mold return lifting: After the pressure holding is completed, the PLC controller 14 controls the moving end of the hydraulic press body 1 to retract upward, driving the stepped press mold 11 to lift and disengage from the forming cavity.

[0057] S8, Ejection and Removal: The second hydraulic cylinder 82 continues to lift, and the bottom mold 12 is pushed by the U-shaped top block 83 to eject the formed dicing blank from the outer mold 4 cavity, and the formed stepped composite diamond dicing blank is removed.

[0058] The operating principle of the present invention is described as follows: During the cold pressing process in the preparation of the stepped composite diamond dicing, the torsion angle (10°-15°), holding time (e.g., 30 seconds), and hydraulic actuator action sequence are first preset in the PLC controller 14 via the touch panel 15. Then, the stepped composite diamond dicing is cold pressed into shape through the following steps:

[0059] The first step involves placing the support substrate for the stepped composite diamond dicing along the outer wall of the inner mold 10 onto the upper surface of the bottom mold 12. Then, a quantitative mixture of diamond and metal binder is evenly injected into the forming cavity between the outer mold 4 and the inner mold 10. Afterward, the operator issues a work command through the touch panel 15, and the signal is transmitted to the PLC controller 14. The PLC controller 14 controls the moving end of the hydraulic press body 1 to move downward according to the preset program. The moving end of the hydraulic press body 1 drives the U-shaped frame 51, the hollow shell 52, and the connecting cylinder 54 to move downward, thereby driving the stepped die 11 into the forming cavity formed by the outer mold 4 and the inner mold 10. The stepped die 11 continues to press down, cooperating with the bottom mold 12 to axially compress the raw material powder inside the forming cavity, cold-pressing the raw material powder onto the outer periphery of the substrate, and initially forming a stepped composite diamond dicing green blank.

[0060] In the second step, during the above-mentioned pressing and extrusion synchronization process, the PLC controller 14 controls the electric push rod 73 of the drive mechanism 7 to reciprocate. The electric push rod 73 pushes the sealed piston 72 to reciprocate and extrude the hydraulic oil inside the hydraulic cylinder 71. The hydraulic oil is transported to the first cylinder 6 through the three-way reversing solenoid valve 74 and the first oil pipe 75. The moving rod 62 of the first cylinder 6 drives the rack 56 to reciprocate. The reciprocating rack 56 drives the gear 55 meshing with it to achieve forward and reverse rotation. The gear 55 drives the connecting cylinder 54 to reciprocate under the support of two sets of connecting bearings 53. Finally, it drives the stepped die 11 to achieve a reciprocating rotation angle of 10°-15°. The rotation angle of the stepped die 11 is proportional to the reciprocating distance of the electric push rod 73.

[0061] The small-angle reciprocating twisting during the pressing process causes shear displacement of the raw material powder inside the molding cavity, breaking the powder bridging phenomenon in the thin-edged area of ​​the stepped cavity. This promotes the full filling of the raw material powder into each step, improves the mechanical interlocking between raw material powder particles, improves the inherent defect of large radial density difference in the stepped cavity, alleviates stress concentration at the corner of the step, and reduces the generation of micro-cracks inside the green body. This step solves the problems of uneven filling and poor powder interlocking caused by the traditional fixed mold with only axial static pressure, improves the overall structural strength of the green body, and reduces the risk of edge chipping and cracking during demolding.

[0062] In the third step, while the hydraulic press body 1 drives the torsion mechanism 5 and the stepped die 11 to descend and extrude the raw material powder, the pull rod of the air extraction cylinder 91 moves downward synchronously with the hollow shell 52. The air extraction cylinder 91 extracts air from the inside of the sealing cylinder 93 and the molding cavity space through the air pipe 92, the connecting through hole 84 and the ceramic permeable block 85. The ceramic permeable block 85 on the bottom mold 12 opens the molding cavity and extracts the air trapped in the dead corners of the stepped cavity steps and the thin blade gaps. This air extraction mechanism 9 can discharge the interfering air inside the molding cavity, avoid the defects of air holes and material shortage caused by gas retention, further improve the density of the raw material powder cold pressing molding, and avoid the performance degradation of the stepped composite diamond dicing after sintering due to internal air holes.

[0063] Fourthly, after the stepped die 11 is pressed down into place, the pressure sensor 57 at the lower end of the hollow shell 52 contacts and presses against the top of the outer die 4. The pressure sensor 57 sends a pressure signal back to the PLC controller 14. After receiving the signal, the PLC controller 14 controls the three-way reversing solenoid valve 74 to switch, and the hydraulic oil in the hydraulic cylinder 71 is switched to the second oil pipe 76 and delivered to the second cylinder 82. The electric push rod 73 maintains the downward pressure on the sealing piston 72, driving the moving end of the second cylinder 82 to rise upward, driving the U-shaped top block 83 upward. The U-shaped top block 83 passes through the connecting through hole 84 of the hydraulic worktable 2 and pushes the bottom die 12 upward slightly, realizing the stepped die. During the pressure holding stage of bidirectional extrusion with the bottom mold 11 pointing downwards and the bottom mold 12 pointing upwards, the reciprocating twisting of the torsion mechanism 5 stops. That is, the stepped mold 11 no longer twists during the pressure holding stage. The bidirectional pressure can further reduce the density difference of each step of the green blank and avoid the pressure attenuation along the axial direction caused by unidirectional extrusion. The torsion stops during the pressure holding stage, protecting the right-angled contour of the green blank from shearing damage. This ensures the dimensional accuracy of the stepped structure of the stepped composite diamond dicing, solves the problems of pressure attenuation and inconsistent density of different stepped layers in traditional unidirectional static pressure, and ensures the integrity of the stepped contour of the stepped composite diamond dicing green blank, providing a high-quality stepped composite diamond dicing blank for subsequent sintering.

[0064] In the fifth step, after the pressure holding process is completed, the PLC controller 14 controls the moving end of the hydraulic press body 1 to retract upwards, driving the U-shaped frame 51, hollow shell 52 and stepped mold 11 to rise upwards and separate from the forming cavity. At the same time, the drive mechanism 7, in conjunction with the ejector mechanism 8, continues to maintain the lifting state of the second oil cylinder 82. The U-shaped top block 83 drives the bottom mold 12 to continue moving upwards, ejecting the formed stepped composite diamond diced green blank as a whole out of the forming cavity of the outer mold 4. The operator can then remove the green blank, completing one cold pressing forming cycle. After the material is removed, the PLC controller 14 controls the moving end of the electric push rod 73 to retract. At this time, the moving end of the second oil cylinder 82 in the ejector mechanism 8 retracts and resets, and the bottom mold 12 falls back to the bottom of the forming cavity. The bottom mold 12 completes the return limit under the limit of the limit support block 86. Finally, the PLC controller 14 controls the three-way reversing solenoid valve 74 and the electric push rod 73 to cut off the power, waiting for the next forming operation.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cold pressing forming apparatus for preparing stepped composite diamond wafers, comprising a hydraulic press body (1) and a hydraulic worktable (2), characterized in that, The outer wall of the hydraulic press body (1) is fixedly fitted with an L-shaped frame (3). The bottom end of the L-shaped frame (3) is fixedly connected to the upper surface of the hydraulic worktable (2). The upper surface of the hydraulic worktable (2) is fixedly connected with an outer mold (4) and an inner mold (10) for cold pressing. The outer wall of the inner mold (10) is movably fitted with a bottom mold (12) and a stepped mold (11) for cold pressing. The outer walls of the bottom mold (12) and the stepped mold (11) are in sliding contact with the inner wall of the outer mold (4). The moving end of the hydraulic press body (1) is fixedly connected to a torsion mechanism (5) for torsion of the stepped die (11). The upper surface of the hydraulic worktable (2) is fixedly connected to a drive mechanism (7) that controls the torsion of the torsion mechanism (5). The four support legs of the hydraulic workbench (2) are all fixedly connected to the outer walls of the top material mechanism (8). The upper surface of the L-shaped frame (3) is provided with a through hole, and the hole wall is fixedly connected to an air extraction mechanism (9).

2. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 1, characterized in that, The torsion mechanism (5) includes a U-shaped frame (51) fixedly connected to the moving end of the hydraulic press body (1). A hollow shell (52) is fixedly connected to the bottom end of the U-shaped frame (51). A connecting bearing (53) is fixedly connected to both the top and bottom ends of the hollow shell (52). A fixing hole that mates with the outer wall of the outer ring of the connecting bearing (53) is opened at both the top and bottom ends of the hollow shell (52). A connecting cylinder (54) is fixedly connected to the inner wall of both connecting bearings (53). The bottom end is fixedly connected to the upper surface of the stepped mold (11). The outer wall of the connecting cylinder (54) is fixedly sleeved with a gear (55). The side wall of the hollow shell (52) is provided with a round hole, and the hole wall is fixedly connected with a first oil cylinder (6). The moving end of the first oil cylinder (6) is fixedly connected with a rack (56) that meshes with the side wall of the gear (55). The bottom end of the hollow shell (52) is provided with an installation hole, and the hole wall of the installation hole is fixedly connected with a pressure sensor (57) that cooperates with the top of the outer mold (4).

3. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 2, characterized in that, The inner wall of the top end of the connecting cylinder (54) is fixedly connected to a compression limiting block (13) that cooperates with the top end of the inner mold (10).

4. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 3, characterized in that, The first cylinder (6) includes a cylinder housing (61). A through hole is provided on the side wall of the cylinder housing (61), and a moving rod (62) is movably connected to the wall of the through hole. The outer side of the moving rod (62) is fixedly connected to the side wall of the rack (56). A limit block (63) is fixedly connected to the end of the moving rod (62) away from the rack (56). A sealing ring (64) is fixedly sleeved on the outer wall of the limit block (63). The outer wall of the limit block (63) and the outer wall of the sealing ring (64) are both in sliding contact with the inner wall of the cylinder housing (61).

5. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 4, characterized in that, The drive mechanism (7) includes a hydraulic cylinder (71) fixedly connected to the upper surface of the hydraulic worktable (2). A sealing piston (72) is slidably connected to the inner wall of the hydraulic cylinder (71). An electric push rod (73) is fixedly embedded at the top of the hydraulic cylinder (71). The moving end of the electric push rod (73) is fixedly connected to the upper surface of the sealing piston (72). A fixing hole that cooperates with the electric push rod (73) is opened at the top of the L-shaped frame (3). A three-way reversing solenoid valve (74) is fixedly connected to the bottom end of the hydraulic cylinder (71). A first oil pipe (75) is fixedly connected to the top outlet of the three-way reversing solenoid valve (74). The connecting end of the first oil pipe (75) is fixedly connected to the oil nozzle of the first oil cylinder (6). A second oil pipe (76) is fixedly connected to the side outlet of the three-way reversing solenoid valve (74). The connecting end of the second oil pipe (76) passes through the bottom end of the hydraulic worktable (2).

6. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 5, characterized in that, The top material mechanism (8) includes a support plate (81) fixedly connected to the outer wall of the four support legs of the hydraulic worktable (2). The upper surface of the support plate (81) is provided with a through hole, and the hole wall of the through hole is fixedly connected to a second oil cylinder (82) with the same structure as the first oil cylinder (6). The connecting end of the second oil pipe (76) is fixedly connected to the oil nozzle of the second oil cylinder (82). The moving end of the second oil cylinder (82) is fixedly connected to a U-shaped top block (83). The upper surface of the hydraulic worktable (2) is provided with two connecting through holes (84) for the movement of the two vertical parts of the U-shaped top block (83). The top ends of the two vertical parts of the U-shaped top block (83) are fixedly connected to the lower surface of the bottom mold (12). The upper surface of the bottom mold (12) is provided with multiple vent holes, and the hole wall of the vent holes is fixedly connected to a ceramic vent block (85). The lower surface of the bottom mold (12) is fixedly connected to multiple limiting support blocks (86).

7. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 6, characterized in that, The air extraction mechanism (9) includes an air extraction cylinder (91) fixedly embedded at the top of the L-shaped frame (3). The bottom end of the air extraction rod of the air extraction cylinder (91) is fixedly connected to the upper surface of the hollow shell (52). The air nozzle of the air extraction cylinder (91) is fixedly connected to an air pipe (92). The connecting end of the air pipe (92) is fixedly connected to a sealing cylinder (93). The top end of the sealing cylinder (93) is fixedly connected to the outer wall of the hydraulic workbench (2). The bottom end of the sealing cylinder (93) is fixedly connected to the upper surface of the support plate (81). The second oil cylinder (82) is located inside the sealing cylinder (93).

8. The cold pressing forming apparatus for preparing stepped composite diamond wafers according to claim 7, characterized in that, A PLC controller (14) is fixedly connected to the upper surface of the support plate (81), and a touch panel (15) is fixedly connected to the upper surface of the hydraulic worktable (2).

9. A cold pressing process for preparing stepped composite diamond dicings, comprising using the cold pressing apparatus for preparing stepped composite diamond dicings as described in claim 8, characterized in that... The process includes the following steps: S1, parameter preset: input process parameters to PLC controller (14) through touch panel (15), preset the torsion angle of stepped die (11), pressure holding time, and hydraulic actuator action sequence; S2, Loading and positioning: The support base of the stepped composite diamond dicing is fitted onto the outer wall of the inner mold (10) and placed on the upper surface of the bottom mold (12) to complete the positioning. A certain amount of raw material powder mixed with diamond and metal binder is put into the molding cavity between the outer mold (4) and the inner mold (10). S3, Downward Torsional Extrusion: Start the device, the moving end of the hydraulic press body (1) moves downward, driving the torsion mechanism (5) and the stepped die (11) into the molding cavity. The drive mechanism (7) drives the torsion mechanism (5), so that the stepped die (11) reciprocates synchronously during the downward pressing process, applying axial extrusion and shearing action to the powder inside the cavity. S4. Synchronous extraction and degassing: While the stepped die (11) is pressing the raw material powder downwards, the extraction mechanism (9) works synchronously, using the ceramic permeable block (85) on the bottom die (12) to extract the air trapped in the dead corner of the molding cavity step and the thin blade gap, and discharge the gas inside the molding cavity. S5, Pressure signal triggers pressure holding: When the stepped die (11) is pressed down to the position, the pressure sensor (57) contacts the top of the outer die (4) and sends a pressure signal to the PLC controller (14). The PLC controller (14) controls the three-way reversing solenoid valve (74) to reverse, and the hydraulic oil is input into the second oil cylinder (82), which drives the bottom die (12) to rise slightly, forming bidirectional pressure with the stepped die (11) that is kept in the downward state. At the same time, the torsion action of the torsion mechanism (5) is stopped, and the pressure holding stage is entered. S6. Pressure holding molding: Maintain bidirectional pressure and hold pressure for a preset time to complete the dense molding of the stepped composite diamond diced green blank; S7, Press mold return lifting: After the pressure holding is completed, the PLC controller (14) controls the moving end of the hydraulic press body (1) to retract upward, driving the stepped press mold (11) to lift and separate from the forming cavity; S8, ejecting the material: The second oil cylinder (82) continues to lift, and pushes the bottom mold (12) through the U-shaped top block (83) to eject the formed diced blank from the outer mold (4) cavity, and take out the formed stepped composite diamond diced blank.

Images