Design method of mechanical poking mechanism of cold heading machine

Abstract

This application relates to a design method for a mechanical material feeding mechanism in a cold heading machine. By establishing a kinematic mapping model of the main slide stroke and crankshaft rotation angle, the time window for the lateral intervention of the feeding component and the engagement of the longitudinal hook is quantitatively calculated. This allows the forced demolding of thin-walled, deep-hole workpieces to be achieved using the retracting kinetic energy of the main slide. This method ensures strict matching between the feeding action and the cold heading process sequence. While preventing interference with the mechanism's motion, it solves the demolding problem caused by the large clamping force and the inability to install ejector pins on such workpieces, guaranteeing the reliability and safety of demolding even at high speeds.

Description

Technical Field

[0001] This application relates to the field of mechanical manufacturing technology, and in particular to a design method for a mechanical feeding mechanism of a cold heading machine. Background Technology

[0002] Cold heading is one of the main processing methods for fasteners and irregularly shaped parts. During the cold heading process, the metal billet is deformed under high pressure in the mold, and a huge radial tension force and axial friction force are generated between the formed product and the mold. Typically, cold heading machines are equipped with a rear ejector pin, which moves from back to front after the forging is completed, ejecting the product from the fixed mold.

[0003] However, existing demolding technologies face significant challenges when producing products with unique structures, such as large heads, thin rods, and deep holes at the tail. First, when using the reverse extrusion process to form deep holes, the inner wall of the product will be tightly wrapped around the core of the fixed mold, i.e. the rear ejector pin, generating a great clamping force. In order to demold smoothly, for products with thick walls, pusher pads can usually be set at the bottom of the fixed mold, and the product can be pushed away from the core by evenly distributed guide rods. However, for thin-walled products, due to the thin wall thickness (usually only a few millimeters), it is impossible to arrange pusher pads or ejector pins around the core, resulting in insufficient force-bearing surface to carry out the pushing action.

[0004] Therefore, since it is impossible to set a pusher block, when the rear ejector pin pushes the product out of the fixed mold cavity, the product is still tightly held on the rear ejector pin. When the rear ejector pin retracts, the product will retract with it or move back and forth at the front end of the ejector pin, making separation impossible. This not only prevents the product from being ejected, but in severe cases, the product retention can also cause a double-material collision accident during the next mold closing, damaging expensive molds and equipment. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a design method for a mechanical material handling mechanism in a cold heading machine that utilizes the retraction power of the main slider to achieve interference-free forced demolding of thin-walled deep-hole workpieces. This method effectively solves the problems of difficulty in separating such workpieces and the ease with which equipment collisions can occur during high-speed cold heading.

[0006] To achieve the above objectives, this application presents a design method for a mechanical material feeding mechanism in a cold heading machine. The material feeding mechanism includes a transverse drive unit and a longitudinal hook unit. The design method comprises the following steps: Step S1: Obtain workpiece parameters, equipment parameters, and material feeding mechanism parameters. The workpiece parameters include the length l of the workpiece rod and the depth h of the workpiece hole. The equipment parameters include the maximum mold radius Rm, the connecting rod length L, and the crankshaft radius R. The material feeding mechanism parameters include the thickness K of the material feeding cutter head. Step S2: Establish a kinematic mapping model between the main slide stroke S of the cold heading machine and the crankshaft rotation angle θ; Step S3: Based on the thickness K of the feed knife head and the preset first safety clearance δ1, calculate the first slider stroke S1 corresponding to the intervention of the feed mechanism, and use the kinematic mapping model to calculate the starting angle θ1 of the cam's push stroke. Step S4: Determine the lateral cutting stroke H of the feeding mechanism based on the mold radius Rm, and calculate the corresponding cam push stroke angle θ. H And generate when the crankshaft rotation angle is in the interval [θ1, θ1+θ H Cam push-stroke profile data within ]; Step S5: Calculate the distance S that the main slider slides during the lateral cutting motion of the cam. H And according to the inequality S engage ≥S1+S H The engagement position S between the longitudinal hook unit and the feeding mechanism is set. engage ; Step S6: Determine the minimum slider stroke required for complete demolding of the workpiece based on the length l of the rod and the depth h of the hole, and set the return start angle θ2 of the cam so that the main slider stroke S2 ​​corresponding to the return start angle θ2 satisfies S2>L+h+δ2, where δ2 is a preset demolding safety margin.

[0007] Preferably, in step S2, the kinematic mapping model is constructed as follows: Where θ is the crankshaft rotation angle, and S is the displacement of the main slider relative to the front dead center.

[0008] Preferably, in step S3, the first slider stroke S1 is calculated using the following formula: S1=K+δ1 Wherein, δ1 is a preset axial distance constant greater than zero.

[0009] Preferably, in step S4, the lateral cutting stroke H is calculated using the following formula: H=Rm+F+Δ Where F is the distance between the holding center of the feed cutter and the end face of the feed mechanism, and Δ is the preset feed allowance value.

[0010] Preferably, step S4 further includes adjusting the cam push stroke angle θ. H Sub-steps for speed verification: Obtain the maximum permissible lateral movement speed Vmax of the feeding mechanism, as well as the active arm length l1 and driven arm length l2 of the lateral drive unit; Determine the calculated θ HDoes it satisfy the following formula: Where ω is the preset working angular velocity of the crankshaft of the cold heading machine; If the result is negative, then increase θ. H The values ​​are maintained until the above formula is satisfied, and the cam push-stroke profile data is regenerated.

[0011] Preferably, the design method further includes step S7: Based on the cam push profile data generated in step S4 as the main cam profile, and according to the geometric constraints of the rocker arm mechanism in the transverse drive unit, the secondary cam profile data that is conjugate and complementary to the main cam profile is calculated and generated.

[0012] Preferably, the design method further includes a lever ratio adjustment step: When θ increases H The numerical value leads to θ1+θ H When the value is greater than θ2 set in step S6, adjust the ratio of the length of the active arm l1 to the length of the driven arm l2, and return to step S4.

[0013] Preferably, step S5 further includes a verification step of the effective pulling stroke SP of the longitudinal hook unit: Calculate the effective pulling stroke SP=S total -S engage S total The maximum backward travel of the main slider; Verification S P Does condition S meet? P If the parameter is greater than or equal to h, then the current equipment parameters are deemed insufficient to complete demolding.

[0014] Preferably, step S4 further sets the cam's rest angle, which is defined as the crankshaft rotation angle range [θ1+θ]. H [θ2], the radial direction of the cam remains unchanged within the rest angle range.

[0015] Preferably, the design method further includes step S8: The generated cam push-stroke profile data, secondary cam profile data, and the meshing position S are used to... engage The instructions are converted into CNC machining commands to manufacture the material feeding mechanism.

[0016] The design method of the mechanical material feeding mechanism for a cold heading machine in this application establishes a kinematic mapping model of the main slide stroke and crankshaft rotation angle, and quantitatively calculates the time window for the lateral intervention of the feeding component and the engagement of the longitudinal hook. This allows the forced demolding of thin-walled, deep-hole workpieces to be achieved using the retracting kinetic energy of the main slide. This method ensures strict matching between the feeding action and the cold heading process sequence, and solves the demolding problem caused by the large clamping force and inability to install ejector pins on such workpieces while preventing interference with the mechanism's motion. It also guarantees the reliability and safety of demolding during high-speed operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the workpiece to be processed applicable to the embodiments of the present invention.

[0018] Figure 2 This is a schematic diagram of the state when the workpiece is ejected from the mold by the rear ejector pin and the material feeding mechanism has not yet intervened.

[0019] Figure 3 This is a schematic diagram illustrating the principle of determining the lateral cutting stroke (H) of the feeding mechanism in an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram illustrating the principle of determining the engagement position of the longitudinal hook unit in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the kinematic model for establishing the mapping relationship between the main slider stroke (S) and the crankshaft rotation angle (θ) in an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the overall structure of the transverse drive unit and the longitudinal sliding component in the mechanical feeding mechanism used in the embodiments of the present invention.

[0023] Figure 7 This is a schematic diagram showing the installation relationship between the longitudinal hook unit and the main slider in the mechanical feeding mechanism used in this embodiment of the invention.

[0024] Figure 8 This is a schematic diagram illustrating the principle of the cam push stroke profile and action timing design in an embodiment of the present invention.

[0025] Figure 9 This is a flowchart illustrating the design method in an embodiment of the present invention.

[0026] The components include: 1. Feeding knife; 3. Hook; 2. Return spring; 4. Fixed seat; 8. Longitudinal slide; 9. Transverse slide; 10. Transverse slide; 12. First ball pin; 13. Adjusting rod; 14. Second ball pin; 15. Active rocker arm; 18. Passive rocker arm; 19. Rocker arm shaft; 21. Double cam; 30. Workpiece; 31. Head; 32. Rod; 33. Deep hole; 35. Rear punch rod. Detailed Implementation

[0027] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0028] The design method of the mechanical feeding mechanism of the cold heading machine described in this embodiment is based on the following: Figure 6 , Figure 7 and Figure 8 This is achieved through the mechanical feeding mechanism shown.

[0029] like Figure 1 and Figure 2 As shown, the mechanism is used to process a workpiece 30 having a head 31, a rod 32 and a tail with a deep hole 33, with the purpose of forcibly peeling the workpiece 30 off the rear ejector pin 35 of the fixed mold.

[0030] like Figure 6 As shown, the feeding mechanism includes a transverse drive unit and a longitudinal sliding assembly.

[0031] Specifically, the lateral drive unit adopts a cam rocker arm structure, including a double cam 21 containing a main cam and a secondary cam, and a cooperating active rocker arm 15 and a passive rocker arm 18. The active rocker arm 15 is connected to the lateral slide block 10 through an adjusting rod 13 for transmitting power. One end of the adjusting rod 13 is connected to the lateral slide rail 9 through a first ball pin 12, and the other end is connected to the active rocker arm 15 through a second ball pin 14.

[0032] The longitudinal sliding assembly includes a longitudinal slide block 8 and a feed cutter 1. The U-shaped blade at the head of the feed cutter 1 is engaged with the rod portion 32 behind the head of the workpiece 30, i.e., the U-shaped blade is fitted outside the diameter of the rod portion 32. The two ends of the adjusting rod 13 are respectively provided with left and right threads with opposite directions of rotation. By rotating the adjusting rod 13, the lateral position of the feed cutter 1 can be finely adjusted. After adjustment, the locking nut is used to prevent loosening.

[0033] like Figure 7 As shown, the feeding mechanism also includes a longitudinal hook unit, namely a hook 3 installed on the main slide of the cold heading machine.

[0034] See Figure 9 As shown, the design method of this embodiment includes the following steps: Step S1: Obtain parameters.

[0035] refer to Figure 1 The workpiece parameters are obtained, including the length l of the workpiece rod 32 at the workpiece head 31 and the depth h of the workpiece hole.

[0036] At the same time, refer to Figure 5 From the schematic diagram of the mechanism, obtain the equipment parameters of the cold heading machine, including: Maximum mold radius Rm: Take the larger value between the moving mold radius and the fixed mold radius in cold heading; Main connecting rod length L: that is, the length of the connecting rod that drives the main slide block in the main drive system of the cold heading machine; Main crankshaft radius R: that is, the rotation radius of the main drive crankshaft of the cold heading machine.

[0037] In addition, the parameters of the feeding mechanism are obtained, i.e. Figure 1 The thickness K of the head of the feed cutter 1 shown. In this embodiment, as... Figure 2 As shown, K is the thickness of the U-shaped cutting edge at the head of the feed cutter 1.

[0038] Step S2: Establish a kinematic mapping model.

[0039] To achieve precise timing control, a mapping relationship needs to be established between the main slide stroke S of the cold heading machine and the crankshaft rotation angle θ. In this embodiment, the kinematic mapping model is constructed as follows: Where θ is the crankshaft rotation angle, and S is the displacement of the main slider relative to the front dead center. This model establishes a synchronous reference for the cam rotation angle and the linear displacement of the hook.

[0040] Step S3: Determine when the material feeding mechanism should intervene.

[0041] refer to Figure 2 After the main slider retracts a certain distance, the feeding knife 1 can be inserted. Based on the thickness K of the U-shaped blade at the head of the feeding knife 1 and the preset first safety gap δ1, the first slider stroke S1 corresponding to the intervention of the feeding mechanism is calculated. In this embodiment, S1 is calculated using the following formula: S1=K+δ1 Wherein, δ1 is a preset axial distance constant greater than zero, i.e., a safety clearance, for example, 3-5mm, to ensure sufficient clearance for avoidance.

[0042] Subsequently, the calculated S1 is substituted into the kinematic mapping model in step S2, and the push stroke starting angle θ1 of the cam is calculated in reverse.

[0043] Step S4: Design the lateral travel and push stroke profile of the cam.

[0044] refer to Figure 3 First, determine the lateral cutting stroke H of the feeding mechanism, which is calculated using the following formula: H=Rm+F+Δ Where F is the material feeding mechanism, that is, the distance between the holding center of the material feeding knife 1 and the end face of the material feeding mechanism, and Δ is the preset feed allowance value.

[0045] Next, calculate the corresponding cam follow-up motion angle θ. H .

[0046] To prevent damage to the mechanism at high speeds, θ needs to be adjusted. H Verification was performed by obtaining the maximum permissible lateral movement speed Vmax of the feeding mechanism, and Figure 6 The active arm length l1 (i.e., the distance from the center of the roller to the center of the rocker arm shaft 19) and the driven arm length l2 (i.e., the distance from the center of the second ball pin 14 to the center of the rocker arm shaft 19) of the active rocker arm 15 of the transverse drive unit shown are shown.

[0047] Determine the calculated θ H Does it satisfy the following formula: Where ω is the preset working angular velocity of the crankshaft of the cold heading machine.

[0048] If the result is negative (i.e., the speed is too fast), and θ is increased... H The numerical value causes the end angle of the propagation stroke (θ1+θ) H If the return start angle is delayed and exceeds the return start angle θ2 set in step S6 (i.e., a timing conflict has occurred), this method performs a lever ratio adjustment step: Adjust the ratio of design parameters l1 to l2. Specifically, during the mechanism design phase, the design value of the mounting position of the second ball pin 14 on the active rocker arm 15 is changed, for example, by pre-setting different mounting hole positions or changing the length dimension of the rocker arm, thereby changing the length of the active arm l1 and thus changing the speed transmission ratio.

[0049] After completing the parameter adjustment, return to step S4 to recalculate and generate the cam push-stroke profile data.

[0050] In determining the final θ H Then, it generates a crankshaft rotation angle in the interval [θ1, θ1+θ]. H The cam push-stroke profile data within [].

[0051] In this step, the cam's rest angle is also set. Specifically, the rest angle is defined as the crankshaft rotation angle range [θ1+θ]. H [θ2], within this interval, the radial direction of the cam remains unchanged, that is, the push stroke is maintained, so that the feed knife 1 remains stationary after the lateral position is reached, waiting for the longitudinal hook to engage.

[0052] Step S5: Set the engagement position of the longitudinal hook unit.

[0053] refer to Figure 4 and Figure 7 Calculate the distance S that the main slider travels during the lateral cutting motion of the cam, i.e., during the continued retraction of the slider. H And according to the inequality S engage ≥S1+S HThe longitudinal hook unit and the material feeding mechanism are set to the engagement position S between the hook 3 and the fixed base 4. engage This design ensures the logical sequence of first moving laterally to position the object, and then pulling it vertically.

[0054] In some embodiments, this step further includes the effective pulling stroke S of the longitudinal hook unit. P Verification steps: First, calculate the effective pulling stroke S. P =S total -S engage S total The maximum backward travel of the main slider; Subsequently, verify S P Does condition S meet? P If the hole depth is greater than or equal to h, it is determined that the current equipment parameters cannot complete the demolding, and the equipment needs to be replaced or the process parameters need to be changed.

[0055] Step S6: Design the reset timing.

[0056] After workpiece 30 is pulled out, the mechanism needs to reset. The minimum slider stroke required for complete demolding of workpiece 30 is determined based on the rod length l and hole depth h, and the return start angle θ2 of the cam is set such that the main slider stroke S2 ​​corresponding to the return start angle θ2 satisfies: S2>L+h+δ2 Where δ2 is a preset demolding safety margin. This ensures that the ejector blade 1 only begins to retract laterally after the workpiece 30 has completely disengaged from the ejector pin. In some embodiments, such as Figure 6 As shown, the longitudinal return of the feed knife 1 is only affected by friction, and the overall mass is not heavy and the resistance is small. A reset spring 2 can be set to return to its original position using the spring force.

[0057] In some embodiments, in order to eliminate high-speed gaps, this design method further includes step S7.

[0058] Specifically, this step uses the generated cam push-stroke profile data as the main cam profile, and calculates and generates secondary cam profile data that is conjugate and complementary to the main cam profile based on the geometric constraint relationship between the rocker arm mechanism in the lateral drive unit, namely the active rocker arm 15 and the passive rocker arm 18.

[0059] In some embodiments, the design method further includes step S8.

[0060] Specifically, this step generates the cam push-out profile data, the secondary cam profile data, and the meshing position S. engage Converted into CNC machining instructions, such as CNC code or point cloud data, it can be directly used in manufacturing processes such as... Figure 6 The installation and debugging of the double cam 21 and the guide hook 3 are shown.

[0061] The design method for the mechanical material feeding mechanism of a cold heading machine provided in this application establishes a kinematic mapping model between the main slide stroke and the crankshaft rotation angle, and quantitatively calculates the time window for the lateral intervention of the feeding component and the engagement of the longitudinal hook. This allows the forced demolding of thin-walled, deep-hole workpieces to be achieved using the retracting kinetic energy of the main slide. This method ensures strict matching between the feeding action and the cold heading process sequence, and solves the demolding problem caused by the large clamping force and inability to install ejector pins on such workpieces while preventing interference with the mechanism's motion. This guarantees the reliability and safety of demolding during high-speed operation.

[0062] In the description of this application, it should be noted that the terms "vertical", "up", "down", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0063] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0064] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A design method for a mechanical feeding mechanism of a cold heading machine, characterized in that, The feeding mechanism includes a transverse drive unit and a longitudinal hook unit, and the design method includes the following steps: Step S1: Obtain workpiece parameters, equipment parameters, and material feeding mechanism parameters. The workpiece parameters include the rod length l and the workpiece hole depth h. The equipment parameters include the maximum mold radius Rm, the connecting rod length L, and the crankshaft radius R. The material feeding mechanism parameters include the material feeding cutter head thickness K. Step S2: Establish a kinematic mapping model between the main slide stroke S of the cold heading machine and the crankshaft rotation angle θ; Step S3: Based on the thickness K of the feed knife head and the preset first safety clearance δ1, calculate the first slider stroke S1 corresponding to the intervention of the feed mechanism, and use the kinematic mapping model to calculate the starting angle θ1 of the cam's push stroke. Step S4: Determine the lateral cutting stroke H of the feeding mechanism based on the mold radius Rm, and calculate the corresponding cam push stroke angle θ. H And generate when the crankshaft rotation angle is in the interval [θ1, θ1+θ H Cam push-stroke profile data within ]; Step S5: Calculate the distance S that the main slider slides during the lateral cutting motion of the cam. H And according to the inequality S engage ≥S1+S H The engagement position S between the longitudinal hook unit and the feeding mechanism is set. engage ; Step S6: Determine the minimum slider stroke required for complete demolding of the workpiece based on the length l of the rod and the depth h of the hole, and set the return start angle θ2 of the cam so that the main slider stroke S2 ​​corresponding to the return start angle θ2 satisfies S2>L+h+δ2, where δ2 is a preset demolding safety margin.

2. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, In step S2, the kinematic mapping model is constructed as follows: Where θ is the crankshaft rotation angle, and S is the displacement of the main slider relative to the front dead center.

3. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, In step S3, the first slider stroke S1 is calculated using the following formula: S1=K+δ1 Wherein, δ1 is a preset axial distance constant greater than zero.

4. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, In step S4, the lateral cutting stroke H is calculated using the following formula: H=Rm+F+Δ Where F is the distance between the holding center of the feed cutter and the end face of the feed mechanism, and Δ is the preset feed allowance value.

5. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, Step S4 also includes adjusting the cam stroke angle θ. H Sub-steps for speed verification: Obtain the maximum permissible lateral movement speed Vmax of the feeding mechanism, as well as the active arm length l1 and driven arm length l2 of the lateral drive unit; Determine the calculated θ H Does it satisfy the following formula: Where ω is the preset working angular velocity of the crankshaft of the cold heading machine; If the result is negative, then increase θ. H The values ​​are maintained until the above formula is satisfied, and the cam push-stroke profile data is regenerated.

6. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, The design method further includes step S7: Based on the cam push profile data generated in step S4 as the main cam profile, and according to the geometric constraints of the rocker arm mechanism in the transverse drive unit, the secondary cam profile data that is conjugate and complementary to the main cam profile is calculated and generated.

7. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 5, characterized in that, The design method also includes a leverage ratio adjustment step: When θ increases H The numerical value leads to θ1+θ H When the value is greater than θ2 set in step S6, adjust the ratio of the length of the active arm l1 to the length of the driven arm l2, and return to step S4.

8. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, Step S5 further includes a verification step of the effective pulling stroke SP of the longitudinal hook unit: Calculate the effective pulling stroke S P =S total -S engage S total The maximum backward travel of the main slider; Verification S P Does condition S meet? P If the parameter is greater than or equal to h, then the current equipment parameters are deemed insufficient to complete demolding.

9. The design method of the mechanical feeding mechanism of the cold heading machine according to claim 1, characterized in that, In step S4, the rest angle of the cam is also set, and the rest angle is defined as the crankshaft rotation angle range [θ1+θ]. H [θ2], the radial direction of the cam remains unchanged within the rest angle range.

10. The design method of the mechanical feeding mechanism of the cold heading machine according to any one of claims 1 to 9, characterized in that, The design method further includes step S8: The generated cam push-stroke profile data, secondary cam profile data, and the meshing position S are used to... engage The instructions are converted into CNC machining commands to manufacture the material feeding mechanism.

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