A method and apparatus for forming a semi-solid continuous thixomolded sleeve by a flat die

Abstract

The application discloses a kind of flat type semi-solid continuous thixotropic extrusion sleeve forming methods, belong to metal semi-solid forming technical field.It includes the following steps (1) preheating;(2) initial station blank heating;(3) station movement;(4) die closing;(5) die opening;(6) demolding;(7) station repeats;The application is through the cooperation of upper rectangular plate, lower rectangular plate, male die, female die, translation mechanism, upper driving mechanism and lower driving mechanism, realize the thixotropic forming of the embryo in the multiple die holes on female die, extrusion process is stable controllable, semi-solid billet has no spatter risk;Gas inclusions in forming environment are less, can effectively avoid billet oxidation, finally obtain the sleeve parts of organization compact, excellent mechanical properties, improve sleeve forming efficiency and quality, semi-solid extrusion forming belongs to near net shape process, later cutting processing amount reduces by more than 60%, material utilization rate can reach more than 90%, significantly reduce raw material loss.

Description

Technical Field

[0001] This invention relates to the field of metal semi-solid forming technology, specifically to a method and apparatus for forming a flat semi-solid continuous thixotropic extrusion bushing. Background Technology

[0002] Semi-solid forming is an advanced processing technology that lies between all-liquid casting and all-solid forging. It utilizes the special state of metal within the temperature range where solid and liquid coexist to form components. Compared with traditional liquid forming technology, semi-solid forming has advantages such as lower forming temperature, smoother filling process, less thermal shock to the mold, and higher density of formed parts. Compared with traditional solid forming technology, it has advantages such as higher material utilization, shorter process flow, ability to form complex components in one step, higher production efficiency, and lower production cost. However, because the metal has both liquid and solid phases in the semi-solid forming process, the rigid-plastic or viscoplastic deformation of the solid phase and the viscous flow of the liquid phase are prone to mismatch during forming, which can lead to solid-liquid separation, resulting in defects such as element segregation, uneven structure, shrinkage porosity, and shrinkage cavities. This is especially prominent in the forming of high solids content parts and deep cavity parts such as bushings.

[0003] Semi-solid forming processes mainly include two routes: rheological forming and thixotropic forming. Thixotropic forming typically involves first preparing a solid preform with a spherical, non-dendritic structure, then reheating it to the semi-solid temperature range. Utilizing the thixotropic properties of the metal in this state—high static viscosity and rapid viscosity reduction under shear—the component is formed through high-pressure filling or extrusion. This process offers advantages such as good oxidation control, stable microstructure and properties, and strong material compatibility, making it suitable for automated and large-scale production. In contrast, rheological forming features a shorter process flow, lower energy consumption, and higher efficiency, but it requires stricter process window and stability.

[0004] Although thixoforming offers greater stability advantages in industrial applications, existing thixoforming equipment often operates in a single-station or intermittent manner. This makes it difficult to parallelize the heating, forming, and demolding processes, resulting in low production efficiency. Furthermore, insufficient coordination between the heating device and the forming die leads to temperature fluctuations in the billet during transfer or waiting, causing instability in the semi-solid state. Simultaneously, the heating area and length in existing thixoforming processes are typically fixed, making dynamic adjustment based on billet size or forming stage difficult. Under high solid fraction conditions, this can easily lead to localized overheating or underheating, exacerbating the problem of uncoordinated solid-liquid phase deformation and limiting the application of thixoforming in continuous, high-efficiency, and complex bushing-type parts forming. Therefore, it is necessary to maintain the structural stability advantages of thixoforming while achieving continuous, efficient, and precise control of the semi-solid heating and forming processes through coordinated structural and process design. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this invention provides a method and apparatus for forming flat, semi-solid, continuous thixotropic extrusion bushings. This apparatus and method can continuously realize the heating, forming, and demolding processes, thereby improving the efficiency and quality of bushing forming.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a method for forming a flat semi-solid continuous thixotropic extrusion bushing, the innovation of which lies in the following steps: (1) Preheating: Preheat the die holes of the punch and die, then spray graphite release agent on the outer surface of the punch and the inner surface of the die hole, and place metal blanks in each die hole; (2) Initial station blank heating: The initial station is moved to the underside of the induction heating coil by the translation mechanism, the upper rectangular plate is driven to move down, and the punch and the induction heating coil are driven down to the mold closing position. The metal blank in the initial station is induction heated and kept warm by the induction heating coil. After keeping warm, the upper rectangular plate is driven to move the punch and the induction heating coil up to reset. (3) Station movement: The die is moved closer to the punch, so that the initial station is moved below the punch and the die hole adjacent to the initial station is moved below the induction heating coil. (4) Mold closing: Drive the upper rectangular plate to move down, and drive the punch and induction heating coil to move down. The punch performs bushing extrusion forming on the semi-solid metal blank with high solid phase that has been heated in the initial station and holds the pressure to form the bushing part; the induction heating coil simultaneously heats and holds the metal blank in the corresponding die hole, and the heating conditions are the same as in step (2). (5) Mold opening: drive the upper rectangular plate to move up, which in turn moves the punch up; the induction heating coil is kept stationary by the upper drive mechanism, so that after the punch is demolded, it continues to induction heat and keep the metal blank in the corresponding mold hole. The lower hydraulic cylinder of the lower drive mechanism drives the ejector rod to move the ejector rod up. The ejector rod drives the ejector core to move up synchronously, so as to realize the ejection of the bushing part. After ejection, the ejector rod is reset, and the ejected bushing part is immediately subjected to water quenching treatment. (6) Demolding: When the ejector pin is reset to the bottom, after heating is completed, the induction heating coil moves up to be flush with the punch. The lower rectangular plate is driven by the translation mechanism to continue to translate towards the punch until the next adjacent mold hole is located below the induction heating coil. (7) Repeat steps (4)-(6) to complete the heating, synchronous extrusion and water quenching of the metal blanks in all the die holes in sequence; after the bushing part in the last die hole has completed the extrusion and water quenching, the die is reset to the initial position by the translation mechanism, that is, the initial position is located below the induction heating coil, and the next round of bushing part forming work steps is entered.

[0007] Preferably, in step (1), the preheating temperature of the die hole of the punch and die is 350-450℃ and the preheating time is 0-30s.

[0008] Preferably, in step (2), the metal billet is placed at the center of the upper surface of the ejector core, and the induction heating coil is coaxially sleeved on the outside of the metal billet when heating it; the temperature of the metal billet heated by the induction heating coil is 10-50℃ above the solidus, and the heating rate of the metal billet by the induction coil is r=5-15℃ / s; the induction heating time is... Where T is the target heating temperature of the metal billet, T0 is the initial temperature of the metal billet when induction heating begins, and r is the heating rate of the induction heating coil; the holding time is 10-30s.

[0009] Preferably, in step (4), the extrusion speed of the punch on the metal blank is 10-20 mm / s, the extrusion time is 6-15 s, the holding pressure is 100-300 MPa, and the holding time is 10-20 s.

[0010] Preferably, in step (6), the induction heating coil moves upward at a speed of 10-20 mm / s until it is flush with the punch.

[0011] Preferably, the mold closing or opening stroke is H=120-150mm; the ejector pin's one-way stroke is 120-150mm, and the upward ejection and downward retraction speed is 10-20mm / s, so the ejection or retraction time is 6-15s; the distance between adjacent stations is 100-150mm, and the station switching movement speed is 15-25mm / s, so the station switching time is 4-10s; the bushing removal time is 3-10s. This invention also provides an apparatus for forming bushing parts based on the above-mentioned flat semi-solid continuous thixotropic extrusion method, comprising an upper rectangular plate and a lower rectangular plate, the innovation of which is: The upper rectangular plate has a punch, an induction heating coil, and an upper driving mechanism arranged side by side at its bottom. The heating coil is driven to move up and down by the upper driving mechanism. A die is slidably arranged on the lower rectangular plate. A translation mechanism is also provided on the side of the lower rectangular plate. The die moves by the translation mechanism. Several mold holes are arranged in a row on the die. Each mold hole has an ejector core at its bottom. Each mold hole has a through hole at its bottom. A push rod is provided below the corresponding through hole. The push rod is connected to the lower driving mechanism. The push rod moves up and down by the lower driving mechanism to eject the bushing and reset it. The extension direction of the rows of die holes is the same as the parallel direction of the punch and the induction heating coil, and the spacing between two adjacent die holes is the same as the spacing between the punch and the induction heating coil.

[0012] Preferably, the upper drive mechanism includes an upper fixed frame, an upper hydraulic cylinder, and an upper mounting plate. The upper fixed frame is located on the upper rectangular plate, the upper hydraulic cylinder is located at the top inside the upper fixed frame, the upper mounting plate is located at the lower extension end of the upper hydraulic cylinder, and the upper mounting plate is provided with a connector. The connector passes through the upper rectangular plate, and the lower end of the connector is connected to the upper end of the heating coil.

[0013] Preferably, the lower rectangular plate is provided with a guide rail, and the die is slidably sleeved on the guide rail; the translation mechanism includes a transmission box, a servo motor, a gear and a moving column, one end of the moving column is fixedly connected to the end of the die, and the extending direction is consistent with the extending direction of the row of die holes, and the upper surface of the moving column is provided with moving teeth; the transmission box is fixed on the lower rectangular plate, the servo motor is located in the transmission box, the gear is located on the output shaft of the servo motor, and the gear meshes with the moving teeth on the moving column.

[0014] Preferably, the lower drive mechanism includes a base, a lower hydraulic cylinder, and a lower mounting plate. The lower hydraulic cylinder is mounted on the base, the lower mounting plate is located at the telescopic upper end of the lower hydraulic cylinder, and the push rod is fixed on the upper surface of the lower mounting plate, with the push rod located directly below the punch.

[0015] This invention provides a method and apparatus for forming a flat, semi-solid, continuous thixotropic extrusion bushing, which has the following advantages: (1) The translation mechanism of this invention is fixed to a gear and a moving column through meshing transmission. Driven by a servo motor, the rotational motion of the motor is converted into the linear reciprocating motion of the moving column, thereby driving the die to move left and right along the guide rail. The sliding direction is switched by controlling the forward and reverse rotation of the servo motor. Combined with the position feedback of the motor encoder and the calculation of the rack tooth pitch, the sliding stroke and positioning accuracy of the lower rectangular plate are controlled. With the coordinated operation of station material replenishment and part removal, continuous extrusion production can be realized, effectively shortening the production cycle and adapting to the needs of mass production of bushings.

[0016] (2) The present invention achieves continuous thixotropic forming of the blanks in multiple die holes on the die through the cooperation of the upper rectangular plate, lower rectangular plate, punch, die, translation mechanism, upper drive mechanism and lower drive mechanism. The extrusion process is stable and controllable, and there is no risk of splashing of semi-solid blanks. The amount of gas entrapment in the forming environment is small, which can effectively avoid the oxidation of blanks and finally obtain bushing parts with dense structure and excellent mechanical properties, improve the forming efficiency and quality of bushings. Semi-solid extrusion forming is a near-net-shape forming process, which reduces the amount of subsequent cutting processing by more than 60% and the material utilization rate can reach more than 90%, significantly reducing raw material loss.

[0017] (3) The induction heating coil and punch described in this invention are fixed to the upper rectangular plate, which is connected to the upper end of the hydraulic press and is controlled by the hydraulic press to move up and down synchronously. The induction heating coil can move up and down independently through the upper drive mechanism, which can better control the heating and holding time of the metal billet. Through the cyclic switching of multiple workstations, only one set of punch and induction heating coil is needed to achieve continuous heating and extrusion. The equipment structure is simple and saves costs.

[0018] (4) In this invention, the ejector core corresponds one-to-one with the die hole and is internally assembled at the bottom of each die hole, with the blank placed centrally on the ejector core. At the same time, the ejector rod and the ejector core adopt contact transmission, and both are made of H13 hot work die steel, which has excellent high temperature strength and anti-stick properties. After the extrusion and holding pressure is completed, the ejector rod is driven upward by the lower hydraulic cylinder to smoothly eject the bushing part along the die hole axis, which not only avoids deformation or surface damage caused by the part sticking to the die, but also realizes the part quickly detaches from the die, accurately matches the station switching rhythm, and further ensures the smoothness of continuous production.

[0019] (5) The present invention adopts a mold layout with the punch on top and the die on the bottom, which is suitable for installation on a vertical hydraulic press, realizing continuous production of bushing parts while occupying little space. The mold consists of a punch and a die forming a mold cavity, so that the blank is subjected to triaxial stress in the cavity, improving the uniformity and density of the bushing.

[0020] (6) The present invention uses an induction heating coil to achieve high-frequency induction heating, which has high heating efficiency and can ensure the temperature consistency of each part of the metal billet; after the bushing is extruded, it is subjected to rapid water quenching treatment to effectively preserve the structure after forming. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the flat continuous thixotropic extrusion die of the present invention.

[0022] Figure 2 This is a process flow diagram of the plate-type semi-solid continuous thixotropic extrusion bushing forming method of the present invention.

[0023] Figure 3 This is a cross-sectional view of the mold hole of the present invention.

[0024] Figure 4 This is a schematic diagram of the connection structure between the induction heating coil and the upper driving mechanism of the present invention.

[0025] Figure 5 This is a schematic diagram of the connection between the die and the translation mechanism of the present invention.

[0026] Figure 6 This is a schematic diagram of the connection between the top rod and the lower drive mechanism of the present invention.

[0027] Figure 7This is a schematic diagram of a bushing part formed by the apparatus and method of the present invention.

[0028] The components are as follows: 1. Upper rectangular plate; 2. Lower rectangular plate; 3. Punch; 4. Induction heating coil; 5. Upper drive mechanism; 51. Upper fixed frame; 52. Upper hydraulic cylinder; 53. Upper mounting plate; 54. Connecting piece; 6. Die; 7. Translation mechanism; 71. Guide rail; 72. Transmission box; 73. Servo motor; 74. Gear; 75. Moving column; 76. Moving gear; 8. Ejector rod; 9. Lower drive mechanism; 91. Base; 92. Lower hydraulic cylinder; 93. Lower mounting plate; 10. Mold hole; 11. Ejector core; 12. Through hole; 13. Hydraulic press. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the content described.

[0030] This invention provides a flat-plate semi-solid continuous thixotropic extrusion bushing forming device, comprising an upper rectangular plate 1 and a lower rectangular plate 2. The upper rectangular plate 1 is lifted and lowered by a hydraulic press 13, and the lower rectangular plate 2 can be mounted on a worktable. Its specific structure is as follows: Figure 1 As shown, a punch 3, an induction heating coil 4, and an upper driving mechanism 5 are arranged side by side at the bottom of the upper rectangular plate 1. The induction heating coil 4 is driven to move up and down by the upper driving mechanism 5. A die 6 is slidably arranged on the lower rectangular plate 2. A translation mechanism 7 is also provided on the side of the lower rectangular plate 2. The die 6 moves through the translation mechanism 7. Several mold holes 10 are arranged in a row on the die 6. Each mold hole 10 has an ejector core 11 at the bottom. Each mold hole 10 has a through hole 12 at the bottom. A push rod 8 is provided below the corresponding through hole 12. The push rod 8 is connected to the lower driving mechanism 9. The push rod 8 moves up and down through the lower driving mechanism 9 to eject the bushing and reset.

[0031] The extension direction of the row of die holes 10 is the same as the parallel direction of the punch 3 and the induction heating coil 4, and the distance between two adjacent die holes 10 is the same as the distance between the punch 3 and the induction heating coil 4.

[0032] The upper drive mechanism 5 of the present invention includes an upper fixed frame 51, an upper hydraulic cylinder 52, and an upper mounting plate 53, as shown below. Figure 4 As shown, the upper fixed frame 51 is located on the upper surface of the upper rectangular plate 1, the upper hydraulic cylinder 52 is located inside the top of the upper fixed frame 51, the upper mounting plate 53 is located at the lower end of the extension of the upper hydraulic cylinder 52, and the upper mounting plate 53 is provided with a connector 54. The connector 54 passes through the upper rectangular plate 1 and the lower end of the connector 54 is connected to the upper end of the heating coil.

[0033] When the upper driving mechanism 5 of the present invention is in use, when the upper rectangular plate 1 moves upward and the induction heating coil 4 needs to maintain heating, the upper hydraulic cylinder 52 is driven to extend downward, driving the upper mounting plate 53 to move downward, and indirectly through the upper connecting piece 54 to move downward, so that when the lower rectangular plate 2 moves upward, the induction heating coil 4 maintains the heating of the corresponding metal blank until the heating is completed, and then the upper hydraulic cylinder 52 is retracted, driving the upper mounting plate 53, the connecting piece 54 and the induction heating coil 4 to return to the upper level until the induction heating coil 4 and the punch 3 are on the same horizontal plane.

[0034] The lower rectangular plate 2 of this invention is provided with a guide rail 71, such as... Figure 5 As shown, the die 6 is slidably sleeved on the guide rail 71; the translation mechanism 7 includes a transmission box 72, a servo motor 73, a gear 74 and a moving column 75. One end of the moving column 75 is fixedly connected to the end of the die 6, and its extension direction is consistent with the extension direction of the row of die holes 10. The upper surface of the moving column 75 is provided with moving teeth 76; the transmission box 72 is fixed on the lower rectangular plate 2, the servo motor 73 is located inside the transmission box 72, the gear 74 is located on the output shaft of the servo motor 73, and the gear 74 meshes with the moving teeth 76 on the moving column 75.

[0035] The translation mechanism 7 of the present invention is used as follows: the rotation of the servo motor 73 drives the gear 74 to rotate, and the rotation of the gear 74 drives the translation of the moving column 75, which in turn drives the die 6 to translate on the lower rectangular plate 2. The sliding direction is switched by controlling the forward and reverse rotation of the servo motor 73. Combined with the position feedback of the motor encoder and the calculation of the rack tooth pitch, the sliding stroke and positioning accuracy of the lower rectangular plate 2 are precisely controlled.

[0036] The lower drive mechanism 9 of the present invention includes a base 91, a lower hydraulic cylinder 92, and a lower mounting plate 93, as shown below. Figure 6 As shown, the lower hydraulic cylinder 92 is mounted on the base 91, and the lower mounting plate 93 is located at the upper extension end of the lower hydraulic cylinder 92. The push rod 8 is fixed to the upper surface of the lower mounting plate 93, and the push rod 8 is located directly below the punch 3. The die 6 of this invention is mounted on the lower rectangular plate 2. Figure 1 In one implementation, no worktable is provided; the lower drive mechanism is directly located at the bottom of the upper rectangular plate and directly penetrates the upper rectangular plate to eject the bushing. In another implementation, the upper rectangular plate 1 can be located on the worktable, and both the upper rectangular plate 1 and the worktable have openings through which the push rod 8 can pass, with the lower drive mechanism 9 located at the bottom of the worktable.

[0037] When the lower drive mechanism 9 of the present invention is in use, that is, when the bushing part needs to be pushed upward, the lower hydraulic cylinder 92 extends, driving the push rod 8 upward through the opening opened on the upper rectangular plate 1 and the worktable, and through the through hole 12 on the die 6 to contact and push out the core 11, driving the bushing to move upward until the bushing is removed. The lower hydraulic cylinder 92 retracts, driving the push rod 8 to move downward and reset.

[0038] The present invention has two lower hydraulic cylinders 92 and two upper hydraulic cylinders 52, which are symmetrically arranged. By controlling the synchronous extension and retraction of the two hydraulic cylinders through the hydraulic control system, the ejector rod 8 and the induction heating coil 4 can be driven to move up and down precisely in the vertical direction, so as to realize the functions of workpiece ejection, mold reset, and continuous heating and heat preservation of the induction heating coil 4 before rising. The synchronous design of the two cylinders can ensure that the ejector rod 8 is subjected to uniform force and moves smoothly, avoiding uneven load during ejection.

[0039] like Figure 3 As shown, Figure 3 The diagram on the left shows a cross-sectional view of the bushing after it has been formed, with the punch 3 moving upwards and the ejector pin 8 moving upwards in preparation for ejecting the bushing. Figure 3 The diagram on the right shows a cross-sectional view of an empty mold cavity.

[0040] Based on the above-mentioned device, the present invention achieves the forming of flat semi-solid continuous thixotropic extrusion bushing parts through the following method, and the schematic diagram of the steps is shown below. Figure 2 As shown, it includes the following steps: (1) Preheat the die holes of the punch and die, then spray graphite release agent on the outer surface of the punch and the inner surface of the die hole, and place metal blanks in each die hole.

[0041] The preheating temperature of the punch and die orifices is 350-450℃, and the preheating time is 20-30s.

[0042] (2) Move the die through the translation mechanism to move the initial station directly below the induction heating coil, drive the upper rectangular plate to move down, and drive the punch and the induction heating coil to move down to the mold closing position. The metal blank in the initial station is induction heated and kept warm by the induction heating coil. After keeping warm, drive the upper rectangular plate to move the punch and the induction heating coil to move up and reset.

[0043] The metal billet is placed at the center of the upper surface of the ejector core. The induction heating coil is coaxially sleeved around the outside of the metal billet during heating. The induction heating coil heats the metal billet to a temperature 10-50°C above the solidus line, and the heating rate of the induction coil is r = 5-15°C / s. The induction heating time is... Where T is the target heating temperature of the metal billet, T0 is the initial temperature of the metal billet when induction heating begins, and r is the heating rate of the induction heating coil; the holding time is 10-30s.

[0044] (3) Move the die closer to the punch so that the initial position moves below the punch and the die hole adjacent to the initial position moves below the induction heating coil. (4) Drive the upper rectangular plate to move down, and drive the punch and the induction heating coil to move down. The punch performs bushing extrusion forming on the semi-solid metal blank with high solid phase that has been heated in the initial station and holds the pressure to form the bushing part. The induction heating coil simultaneously heats and holds the metal blank in the corresponding die hole. The heating conditions are the same as in step (2).

[0045] The extrusion speed of the punch on the metal blank is 10-20 mm / s, and the extrusion time is 6-15 s; the holding pressure is 100-300 MPa, and the holding time is 10-20 s.

[0046] (5) Drive the upper rectangular plate to move up, which in turn drives the punch to move up; the induction heating coil is kept stationary through the upper drive mechanism, so that after the punch is demolded, it continues to induction heat and keep the metal blank in the corresponding die hole. The lower hydraulic cylinder of the lower drive mechanism drives the ejector rod to move up, and the ejector rod drives the ejector core to move up synchronously, so as to realize the ejection of the bushing part. After ejection, the ejector rod is reset, and the ejected bushing part is immediately subjected to water quenching treatment. (6) When the ejector pin is reset to the bottom, the induction heating coil moves up to be flush with the punch after the heating and heat preservation are completed. The lower rectangular plate is driven by the translation mechanism to continue to translate towards the punch until the next adjacent die hole is located below the induction heating coil. The induction heating coil moves up at a speed of 10-20 mm / s to be flush with the punch.

[0047] (7) Repeat steps (4)-(6) to complete the heating, synchronous extrusion and water quenching of the metal blanks in all the die holes in sequence; after the bushing part in the last die hole has completed the extrusion and water quenching, the die is reset to the initial position by the translation mechanism, that is, the initial position is located below the induction heating coil, and the next round of bushing part forming work steps is entered.

[0048] A solids content of 60-85% is required to ensure the balance, density, and structural stability of the bushing parts. A high solids content necessitates a reduced heating rate to avoid excessive liquid phase formation. The mold closing or opening stroke is H=120-150mm; the ejector pin's unidirectional stroke is 120-150mm; the upward ejection and downward retraction speeds are 10-20mm / s, resulting in an ejection or retraction time of 6-15s; the distance between adjacent stations is 100-150mm; the station switching movement speed is 15-25mm / s, resulting in a station switching time of 4-10s; and the bushing removal time is 3-10s. The bushing removal action involves ejecting the bushing and then removing it from the equipment.

[0049] During the entire process of extrusion and pressure holding, mold opening, ejection, and part removal of the bushing at the initial station, the second bushing is simultaneously activated by induction heating. After part removal is completed, the time required to heat to the target temperature is supplemented and the temperature is maintained. The induction heating coil moves upward, and the translation mechanism drives the die to move to the next station. The next bushing is extruded and formed in a cycle, making full use of the waiting time of the subsequent actions of the first part and improving the forming efficiency of the bushing parts.

[0050] Based on the above-described apparatus and method, the present invention will be further illustrated by the following embodiments. Example 1 This example demonstrates a continuous thixotropic extrusion forming method for flat copper alloy bushing parts. The ZCuSn10P1 copper alloy has a solidus temperature of 876.1℃ and a liquidus temperature of 1024.2℃. The specific steps for continuous operation of the apparatus are as follows: (1) First, preheat the punch and die hole to 450°C for 30 seconds. Spray graphite release agent on the outer surface of the punch and the inner surface of the die hole. Place the ZCuSn10P1 copper alloy blank with dimensions of 65×35×35mm into each station. (2) The stroke of mold closing or mold opening is 150mm. The hydraulic press lowers the punch to the mold closing position at a speed of 15mm / s. The induction heating coil heats the ZCuSn10P1 alloy billet at the initial station. The induction heating rate r is 15℃ / s. It takes 58s to heat to 890℃ and hold for 30s. 25℃ is the initial room temperature. After holding, the upper rectangular plate drives the punch and the induction heating coil to move upward and reset.

[0051] (3) The mold opens and the translation mechanism drives the die to move to the left by one station at a speed of 25 mm / s. The distance between two adjacent die holes is 150 mm. This makes the die hole below the initial station move to the lower part of the punch and the die hole adjacent to the initial station move to the lower part of the induction heating coil.

[0052] (4) Mold closing: The heated ZCuSn10P1 billet is subjected to bushing extrusion (200MPa) at the initial station and held for 15s. At the same time, the ZCuSn10P1 billet is induction heated at a rate of 15℃ / s at the next station to 890℃ above the solidus line and held for 15s.

[0053] (5) The mold opens and the punch moves upward while the induction heating coil continues to heat the metal billet at the current station. The ejector rod stroke is 150mm. The ejector rod drives the ejector core upward at a speed of 15mm / s to eject the bushing formed by the ejector station. The bushing part after extrusion is taken out and subjected to rapid water quenching.

[0054] (6) The ejector pin is reset to the bottom, the induction heating coil continues to heat until the heat preservation is completed, and then gradually moves upward at a speed of 15 mm / s to the same level as the punch. Then the translation mechanism drives the die to move to the left one station at a speed of 25 mm / s.

[0055] (7) Repeat steps (4)-(6) to sequentially complete the extrusion, synchronous heating, and water quenching of the ZCuSn10P1 billet at the workstation; after the ZCuSn10P1 bushing part at the workstation has completed extrusion and water quenching, the guide rail mechanism drives the die to move to the right and reset to the initial position at the rightmost end, entering the next round of continuous work. The prepared part is as follows Figure 7 As shown.

[0056] The ZCuSn10P1 bushing parts prepared in this embodiment require only a small amount of machining. They have a smooth surface, dense structure, no scratches or cracks, and good mechanical properties.

[0057] Example 2 This embodiment describes a continuous thixotropic extrusion method for flat plates of 6061 aluminum alloy bushing parts. The solidus temperature of the 6061 aluminum alloy is 582.2℃, and the liquidus temperature is 655.4℃. The manufacturing process is as follows: Figure 2 As shown, the specific steps are as follows: (1) First, preheat the punch and die to 400°C for 25 seconds, and spray graphite release agent on the surface of the punch and die; place the 6061 aluminum alloy blank with dimensions of 65×35×35mm into each station.

[0058] (2) The hydraulic press lowers the mold to the mold closing position at a speed of 20 mm / s. The mold closing stroke is 140 mm. The induction heating coil of the 6061 aluminum alloy billet at the initial station has a heating rate r of 10℃ / s. It takes 58s to heat it to 600℃ and keep it warm for 20s. 25℃ is the initial room temperature. After keeping it warm, the upper rectangular plate drives the punch and the induction heating coil to move upward and reset.

[0059] (3) The mold opens and the translation mechanism drives the die to move to the left by one station at a speed of 20 mm / s. The distance between two adjacent die holes is 120 mm. This makes the die hole move below the punch and the die hole adjacent to the initial station move below the induction heating coil.

[0060] (4) Mold closing: The heated 6061 aluminum alloy billet is subjected to bushing extrusion (100MPa) and held for 20s at the initial station. At the same time, the 6061 aluminum alloy billet is induction heated at a rate r of 10℃ / s to the solidus line and the time required to reach 600℃ is 58s and then held.

[0061] (5) The mold opens and the punch moves upward while the induction heating coil continues to heat the metal blank at the current station. The ejector rod stroke is 140mm. The ejector rod drives the ejector core upward at a speed of 20mm / s to eject the bushing formed by the ejector station. The bushing part after extrusion is taken out and subjected to rapid water quenching.

[0062] (6) The ejector pin is reset to the bottom, the induction heating coil continues to heat until the heat preservation is completed, and the induction heating coil also gradually moves upward at a speed of 20 mm / s to the same horizontal position as the punch. Then the translation mechanism drives the die to move to the left by one station spacing at a speed of 20 mm / s.

[0063] (7) Repeat steps (4)-(6) to complete the extrusion, synchronous heating and water quenching of 6061 aluminum alloy billet at the workstation in sequence; after the 6061 aluminum alloy bushing part has completed extrusion and water quenching, the guide rail mechanism drives the die to move to the right and reset to the initial position at the rightmost end, and enter the next round of continuous work.

[0064] The semi-solid forming process used in this embodiment combines excellent production continuity and high efficiency. The batch production cycle is stable. The 6061 aluminum alloy bushing parts prepared by the optimized design such as parallel heating have a smooth surface without scratches or cracks, high dimensional accuracy, and good mechanical properties. This achieves a dual guarantee of production efficiency and product quality, and fully meets the core requirements of industrial continuous production.

[0065] Example 3 This embodiment describes a semi-solid continuous thixotropic extrusion method for flat magnesium alloy bushing parts. The solidus temperature of AZ31 magnesium alloy is 595.2℃, and the liquidus temperature is 650.4℃. The specific steps are as follows: (1) First, preheat the punch and die to 350°C for 20 seconds, and spray graphite release agent on the surface of the punch and die; place the AZ31 magnesium alloy blank with dimensions of 65×35×35mm into the work station; (2) The hydraulic press lowers the mold to the mold closing position at a speed of 10 mm / s, with a mold closing stroke of 120 mm. The AZ31 magnesium alloy billet on the initial station is induction heated to 605℃ at a rate of 5℃ / s for 116s (initial temperature 25℃) and held for 10s. (3) The mold opens and the translation mechanism moves the die to the left by one station at a speed of 15 mm / s. The distance between two adjacent die holes is 100 mm. This makes the die hole below the punch and the die hole adjacent to the initial station move below the induction heating coil.

[0066] (4) The mold is closed. The heated AZ31 magnesium alloy is extruded with a bushing (300MPa) at the initial station and held for 10s. At the same time, the AZ31 magnesium alloy billet is induction heated to 605℃ at a rate of 5℃ / s at the next station and held for 10s. (5) The mold opens and the punch moves upward while the induction heating coil continues to heat the metal billet at the current station. The ejector rod stroke is 120mm. The ejector rod drives the ejector core upward at a speed of 10mm / s to eject the bushing formed by the ejector station. The bushing part after extrusion is taken out and subjected to rapid water quenching. (6) The ejector pin is reset to the bottom, the induction heating coil continues to heat until the heat preservation is completed, and then gradually moves upward at a speed of 10 mm / s to the same level as the punch. Then the moving mechanism drives the die to move to the left one station at a speed of 15 mm / s. (7) Repeat steps (4)-(6) to complete the extrusion, synchronous heating and water quenching of AZ31 magnesium alloy billets at each station in sequence; after all AZ31 magnesium alloy bushing parts at all stations have completed extrusion and water quenching, the moving mechanism drives the die to move to the right and reset to the initial position at the rightmost end, and enters the next round of continuous work.

[0067] The semi-solid forming process used in this embodiment combines excellent production continuity and high efficiency, with stable batch production cycle. Through optimized design such as parallel heating, the production cycle is significantly shortened. The prepared magnesium alloy bushing parts have a smooth surface without scratches or cracks, high dimensional accuracy, and good mechanical properties.

[0068] To ensure the semi-solid forming effect and target high solids content of the bushing, process parameters need to be optimized based on the solid-liquid line characteristics of different materials: for ZCuSn10P1 copper alloy with a high solids temperature, the holding time needs to be appropriately extended to 30s to ensure forming density; while 6061 aluminum alloy and AZ31 magnesium alloy have relatively low solids temperatures, and holding times of 20s and 10s are sufficient to meet the forming requirements. Regarding the induction heating rate, achieving a high solids content requires controlling the heating rate to avoid excessive liquid phase formation. Therefore, the heating rate for ZCuSn10P1 copper alloy is set at 15℃ / s, while lower heating rates of 10℃ / s and 5℃ / s are used for 6061 aluminum alloy and AZ31 magnesium alloy, respectively. The forming quality of the parts is ensured through material compatibility parameter design.

[0069] Comparative Example 1 This comparative example uses the same raw materials as Example 1, the difference being that: this comparative example uses a single-station thixotropic extrusion molding process and a box-type resistance furnace for heating, the specific steps of which are as follows: (1) Place a single ZCuSn10P1 copper alloy billet with a size of 65×35×35mm into a box-type resistance furnace (heating rate 5℃ / s), the mold preheating temperature is 450℃, the preheating time is 30s; heat from room temperature 25℃ to the target temperature 890℃, the heating time is 173s, and hold for 30s after heating. (2) Take out the heated billet and quickly transfer it to the mold cavity of the single-station mold (the billet naturally cools down by about 10°C during the transfer process, and the actual temperature of entering the mold is 880°C). This step takes 5 seconds. (3) The hydraulic press drives the punch to close the mold at a speed of 15 mm / s, and performs bushing extrusion forming on the blank in the mold cavity. The mold closing action takes 10 seconds. (4) After extrusion molding, keep the blank in the mold closed and pressurize it for 15 seconds; (5) After the pressure holding is completed, the mold opens (the punch moves upward, which takes 10 seconds), the ejector pin ejects the bushing, and then the part is removed. The ejection and removal of the part take a total of 15 seconds. (6) The removed formed bushing is subjected to rapid water quenching; (7) While water quenching, the ejector pin is reset to the bottom (takes 10s), and then the residual release agent on the surface of the mold cavity is cleaned to prepare for the next blank forming; (8) Each bushing must go through the entire process of “heating-transfer-extrusion-pressure holding-mold opening and ejection-water quenching-reset cleaning” until the required number of bushings are formed. The forming time for one bushing is 288s.

[0070] Comparative Example 2 This comparative example uses the same raw materials and mold as Example 1, the difference being that the mold preheating temperature in this comparative example is 200℃, and the induction heating coil heating rate is 5℃ / s. The specific steps are as follows: (1) First, preheat the punch and die to 200°C for 20 seconds, and spray graphite release agent on the surface of the punch and die; place the ZCuSn10P1 copper alloy blank with dimensions of 65×35×35mm into the work station; (2) The hydraulic press lowers the mold to the mold closing position at a speed of 15 mm / s, and induction heats the ZCuSn10P1 copper alloy billet on the initial station to 885°C at a rate of 5°C / s, which takes 172s and is then held for 30s. (3) The mold is opened and the translation mechanism drives the die to move to the left by one station at a speed of 25 mm / s; the distance between two adjacent die holes is 150 mm; so that the die hole adjacent to the initial station moves to the bottom of the punch and the die hole adjacent to the initial station moves to the bottom of the induction heating coil. (4) The mold is closed. The heated ZCuSn10P1 billet is subjected to bushing extrusion (200MPa) and held for 15s at the initial station. At the same time, the ZCuSn10P1 billet is induction heated to 885℃ in the solid-liquid phase line range at the next station at a rate of 5℃ / s. (5) The mold opens and the punch moves upward while the induction heating coil continues to heat the metal blank of the next station. The ejector rod stroke is 150mm. The ejector rod drives the ejector core to eject the extruded bushing at a speed of 15mm / s. The extruded bushing parts are then subjected to rapid water quenching. (6) The ejector pin is reset to the bottom end, the induction heating coil continues to heat and maintain the temperature for 30 seconds, and then gradually moves upward at a speed of 15 mm / s to the same horizontal position as the punch. The translation mechanism then drives the die to move to the left one station at a speed of 25 mm / s. (7) Repeat steps (4)-(6) to complete the extrusion, synchronous heating and water quenching of ZCuSn10P1 billet at the workstation in sequence; after the ZCuSn10P1 bushing part has completed extrusion and water quenching, the guide rail mechanism drives the die to move to the right and reset to the initial position at the rightmost end, and enter the next round of continuous work. Examples 1-3 and Comparative Examples 1-2 of the present invention all involve the forming of bushings in five workstations. The forming time of the bushing parts obtained in Examples 1-3 and Comparative Examples 1-2 was compared with that of room temperature tensile tests. The test results are shown in Table 1. Table 1 As shown in Table 1, the bushing forming time of Examples 1-3 is much shorter than that of Comparative Examples 1 and 2, and the improved forming efficiency is also significantly higher than that of the two comparative examples. In terms of elongation, the bushings obtained from the embodiments of the present invention all exhibit better elongation than the comparative examples. Therefore, the apparatus of the present invention enables bushing forming to be time-efficient, highly effective, and of better quality.

[0071] In Comparative Example 2, during the entire process of holding pressure on the first bushing, the second mold opening, ejection of the ejector pin, and part removal, the second bushing simultaneously starts induction heating. Similar to the embodiment, this fully utilizes the waiting time of the subsequent actions of the first bushing, without requiring additional time for batch production. However, due to the use of a lower mold temperature and a lower heating rate, the time required for the blank to reach the target temperature is extended, resulting in a decrease in the forming efficiency of the bushing and an impact on its mechanical properties.

[0072] This invention directly performs continuous semi-solid thixotropic extrusion forming on metal billets. By controlling the hydraulic press, induction heating coil, upper and lower drive mechanism, and translation mechanism, the billets at each station receive coordinated synchronous heating-extrusion-ejection integrated operation support during the cyclic operation. During the mold cycle closing, each station sequentially completes billet heating, semi-solid extrusion, part ejection, and water quenching to obtain semi-solid continuously formed bushing parts. This achieves the goal of obtaining parts with high production efficiency, excellent material utilization, and stable quality. This process is continuous and efficient, can achieve large-scale near-net-shape forming, and the parts have uniform and dense structure, excellent mechanical properties, strong adaptability, and are easy to realize mechanized and automated production, with significant forming effect.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for forming a flat, semi-solid, continuous thixotropic extrusion bushing, characterized in that: Includes the following steps: (1) Preheating: Preheat the die holes of the punch and die, then spray graphite release agent on the outer surface of the punch and the inner surface of the die hole, and place metal blanks in each die hole; (2) Initial station blank heating: The initial station is moved to the underside of the induction heating coil by the translation mechanism, the upper rectangular plate is driven to move down, and the punch and the induction heating coil are driven down to the mold closing position. The metal blank in the initial station is induction heated and kept warm by the induction heating coil. After keeping warm, the upper rectangular plate is driven to move the punch and the induction heating coil up to reset. (3) Station movement: The die is moved closer to the punch, so that the initial station is moved below the punch and the die hole adjacent to the initial station is moved below the induction heating coil. (4) Mold closing: Drive the upper rectangular plate to move down, and drive the punch and induction heating coil to move down. The punch performs bushing extrusion forming on the semi-solid metal blank with high solid phase that has been heated in the initial station and holds the pressure to form the bushing part; the induction heating coil simultaneously heats and holds the metal blank in the corresponding die hole, and the heating conditions are the same as in step (2). (5) Mold opening: drive the upper rectangular plate to move up, which in turn moves the punch up; the induction heating coil is kept stationary by the upper drive mechanism, so that after the punch is demolded, it continues to induction heat and keep the metal blank in the corresponding mold hole. The lower hydraulic cylinder of the lower drive mechanism drives the ejector rod to move the ejector rod up. The ejector rod drives the ejector core to move up synchronously, so as to realize the ejection of the bushing part. After ejection, the ejector rod is reset, and the ejected bushing part is immediately subjected to water quenching treatment. (6) Demolding: When the ejector pin is reset to the bottom, after heating is completed, the induction heating coil moves up to be flush with the punch. The lower rectangular plate is driven by the translation mechanism to continue to translate towards the punch until the next adjacent mold hole is located below the induction heating coil. (7) Repeat steps (4)-(6) to complete the heating, synchronous extrusion and water quenching of the metal blanks in all the die holes in sequence; after the bushing part in the last die hole has completed the extrusion and water quenching, the die is reset to the initial position by the translation mechanism, that is, the initial position is located below the induction heating coil, and the next round of bushing part forming work steps is entered.

2. The method for forming a flat, semi-solid, continuous thixotropic extrusion bushing according to claim 1, characterized in that: In step (1), the preheating temperature of the punch and die holes is 350-450℃, and the preheating time is 0-30s.

3. The method for forming a flat, semi-solid, continuous thixotropic extrusion bushing according to claim 2, characterized in that: In step (2), the metal billet is placed at the center of the upper surface of the ejector core. The induction heating coil is coaxially sleeved around the outside of the metal billet during heating. The induction heating coil heats the metal billet to a temperature 10-50°C above the solidus line, and the heating rate of the induction coil is r = 5-15°C / s. The induction heating time is... Where T is the target heating temperature of the metal billet, T0 is the initial temperature of the metal billet when induction heating begins, and r is the heating rate of the induction heating coil; the holding time is 10-30s.

4. The method for forming a flat, semi-solid, continuous thixotropic extrusion bushing according to claim 3, characterized in that: In step (4), the extrusion speed of the punch on the metal blank is 10-20 mm / s, the extrusion time is 6-15 s, the holding pressure is 100-300 MPa, and the holding time is 10-20 s.

5. The method for forming a flat, semi-solid, continuous thixotropic extrusion bushing according to claim 4, characterized in that: In step (6), the induction heating coil moves upward at a speed of 10-20 mm / s until it is flush with the punch.

6. The method for forming a flat, semi-solid, continuous thixotropic extrusion bushing according to claim 5, characterized in that: The mold closing or opening stroke is H=120-150mm; the ejector pin's one-way stroke is 120-150mm, and the upward ejection and downward retraction speed is 10-20mm / s, so the ejection or retraction time is 6-15s; the distance between adjacent stations is 100-150mm, and the station switching movement speed is 15-25mm / s, so the station switching time is 4-10s; the bushing removal time is 3-10s.

7. An apparatus for forming a flat semi-solid continuous thixotropic extrusion bushing part according to any one of claims 1-6, comprising an upper rectangular plate and a lower rectangular plate, characterized in that: The upper rectangular plate has a punch, an induction heating coil, and an upper driving mechanism arranged side by side at its bottom. The heating coil is driven to move up and down by the upper driving mechanism. A die is slidably arranged on the lower rectangular plate. A translation mechanism is also provided on the side of the lower rectangular plate. The die moves by the translation mechanism. Several mold holes are arranged in a row on the die. Each mold hole has an ejector core at its bottom. Each mold hole has a through hole at its bottom. A push rod is provided below the corresponding through hole. The push rod is connected to the lower driving mechanism. The push rod moves up and down by the lower driving mechanism to eject the bushing and reset it. The extension direction of the rows of die holes is the same as the parallel direction of the punch and the induction heating coil, and the spacing between two adjacent die holes is the same as the spacing between the punch and the induction heating coil.

8. The flat-plate semi-solid continuous thixotropic extrusion bushing forming device according to claim 7, characterized in that: The upper drive mechanism includes an upper fixed frame, an upper hydraulic cylinder, and an upper mounting plate. The upper fixed frame is located on the upper rectangular plate, the upper hydraulic cylinder is located inside the top of the upper fixed frame, and the upper mounting plate is located at the lower extension end of the upper hydraulic cylinder. The upper mounting plate is provided with a connector that penetrates the upper rectangular plate, and the lower end of the connector is connected to the upper end of the heating coil.

9. The flat-plate semi-solid continuous thixotropic extrusion bushing forming device according to claim 7, characterized in that: The lower rectangular plate is provided with a guide rail, and the die is slidably sleeved on the guide rail; the translation mechanism includes a transmission box, a servo motor, a gear and a moving column, one end of the moving column is fixedly connected to the end of the die, and the extension direction is consistent with the extension direction of the row of die holes, and the upper surface of the moving column is provided with moving teeth; the transmission box is fixed on the lower rectangular plate, the servo motor is located in the transmission box, the gear is located on the output shaft of the servo motor, and the gear meshes with the moving teeth on the moving column.

10. The flat-plate semi-solid continuous thixotropic extrusion bushing forming device according to claim 7, characterized in that: The lower drive mechanism includes a base, a lower hydraulic cylinder, and a lower mounting plate. The lower hydraulic cylinder is mounted on the base, and the lower mounting plate is located at the telescopic upper end of the lower hydraulic cylinder. The push rod is fixed on the upper surface of the lower mounting plate and is located directly below the punch.

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