A cold heading process for transmission locking nut

Abstract

A cold heading forming process for a transmission locking nut, wherein a blank with an outer contour is punched, and the cold heading station at the punching location includes a first fixing seat, a second fixing seat, an active punch, and a driven punch, wherein the second fixing seat is provided with a second mounting groove adapted to the hexagonal opposite side contour of the second end face side of the blank, and the bottom of the second mounting groove is provided with a second through hole coaxially at the second pre-formed groove; the first fixing seat is provided with a first mounting groove adapted to the step flange contour of the first end face side of the blank, and the first mounting groove is provided with a first through hole coaxially with the first pre-formed groove; the driven punch enters the first pre-formed groove from the first through hole, and the outer peripheral surface of the driven punch is slidably matched with the inner wall of the first pre-formed groove, and a discharge hole is provided in the center; the active punch enters the second pre-formed groove from the second through hole for punching, and when punching to the first pre-formed groove, the driven punch is pushed out from the first through hole to complete the cold heading forming of the nut.

Description

Technical Field

[0001] The invention relates to the technical field of cold heading technology, and in particular to a cold heading forming process for a transmission locking nut. Background Art

[0002] The nut in this application is used for the rear bearing of the output pulley. The specification is M45X1 and the thickness is 11.7mm. It is a non-standard thin nut with high precision requirements. The minimum thickness of the nut is 5-6mm, which makes the design of the clamps in the cold heading process more difficult. Figure 1 The nut structure shown in the figure has a relatively large diameter and a thin-walled stepped flange after being punched ( Figure 1 (7 in the middle) structure and other structural features.

[0003] The problem with the existing technology is that in the mass production of fasteners, the cold heading process is an efficient production method under the current market test, but our company encountered the following problems when using the traditional cold heading process for the above-mentioned non-standard thin nut orders. The material selection for the cold heading process is 40mm in diameter and gradually formed to 55mm on the opposite side, which requires reasonable calculation; due to the structure of the above-mentioned thin-walled flange, coupled with the large diameter of its center hole and the thin remaining thickness after punching, it is often difficult to maintain the dimensional accuracy of the thin-walled flange during the punching process, resulting in a high defective rate in mass production and high production costs.

[0004] The method of drilling and boring holes to overcome the thin-wall flange ensures the dimensional accuracy of the product, but adds additional processes, resulting in increased costs and reduced efficiency.

[0005] Therefore, the conventional direct punching method cannot be used, and the cold heading process needs to be improved to reduce the deformation effect on the thin-wall flange during the punching process and stabilize the dimensional accuracy. This will greatly improve the yield rate of large-scale production, so that the non-standard nut can be formed in one step under the cold heading process, avoiding the cost increase caused by the additional drilling and boring process, thereby improving production efficiency and economic benefits.

[0006] At the same time, traditional cold forging uses multi-station cold forging to form very thin nuts, and it is difficult to clamp the workpiece with a clamp, mainly because excessive mechanical force and instability will cause clamping deformation when clamping the thin nuts, affecting the cold forging product process. Therefore, it is necessary to design a clamp with controllable and stable holding force for this type of thin nut to prevent it from being clamped and deformed during the multi-station transfer process of cold forging. Summary of the invention

[0007] In order to overcome the above-mentioned deficiencies of the prior art, the invention provides a cold heading forming process for a transmission locking nut.

[0008] Invention technical solution: A cold forging process for a transmission locking nut, the process comprising the following steps: forming step 1, cutting a 40mm diameter blank, the blank comprising an axial first end face and a second end face, rough forging the blank to a 50mm profile, shaping it into a chamfered truncated cone structure, and then forging a first preformed groove at the center of the first end face of the blank;

[0009] Forming step 2, transferring the finished blank to the next cold forging station, turning it 180 degrees and forging it to 55 mm, and forging a second pre-forming groove in the center of the second end face of the blank, and preforming the hexagonal opposite sides at the forging on the outer peripheral surface of the blank close to the second end face;

[0010] Forming step 3, transferring the blank to the next cold forging station, turning it 180 degrees, with the first end face facing vertically upward, forging a preformed protrusion on the first end face, and forging a hexagonal opposite side on the outer peripheral surface of the blank on the second end face side;

[0011] Forming step 4, transferring the blank to the next cold heading station to complete the step flange forming;

[0012] Forming step 5, transferring the blank to the next cold heading station for punching, the cold heading station at the punching location includes a first fixing seat, a second fixing seat, an active punch, and a driven punch, the second fixing seat is provided with a second mounting groove adapted to the hexagonal opposite side contour of the second end face side of the blank, and the bottom of the second mounting groove is coaxially provided with a second through hole at the second pre-formed groove; the first fixing seat is provided with a first mounting groove adapted to the step flange contour of the first end face side of the blank, and the first mounting groove is provided with a first through hole coaxial with the first pre-formed groove;

[0013] The driven punch enters the first pre-formed groove through the first through hole, the outer peripheral surface of the driven punch is slidably matched with the inner wall of the first pre-formed groove, and a discharge hole is provided in the center;

[0014] The active punch enters the second pre-formed groove from the second through hole to punch, and when punching to the first pre-formed groove, the driven punch is pushed out from the first through hole to complete the cold heading of the nut.

[0015] The present invention is further configured as follows: the step 2 adopts the maximum forging pressure of 420T in the process, the forging pressures of steps 1 and 3 are both 70% of the maximum forging pressure of step 2, and the forging pressures of steps 4 and 5 are respectively 70% of the forging pressure of the previous step.

[0016] A further configuration of the present invention is that the first preformed groove and the second preformed groove are formed in a stepped shape with a diameter decreasing toward the center.

[0017] The present invention is further configured as follows: the process adopts an electromagnet clamp to clamp and deliver the blank to each cold heading station; the electromagnet clamp includes a pressure gauge, a booster cylinder, a clamp, an iron core, an armature, and a coil. When the coil is energized, the iron core and the armature are attracted, thereby driving the clamp to close and clamp the blank. The clamping force of the clamp is controlled by the strength of the current or the number of turns of the coil, and the booster cylinder drives the clamp to loosen.

[0018] Beneficial effects of the present invention: Figure 2-4 As shown, by gradually extending the diameter of the blank to gradually reach the diameter size requirement, the blank is reversed 180° twice, and pre-formed grooves are respectively formed on the first end face and the second end face to prepare for subsequent punching. At the same time, a pre-formed protrusion is formed on the first end face, and finally formed into a step flange; a hexagonal opposite side pre-formed contour is formed on the outer peripheral surface of the blank on the second end face side, and finally formed into a hexagonal opposite side, thereby completing the outer contour structure of the nut of the present application.

[0019] Then the blank is transferred to the cold heading station of the punching process, and the blank is fixed by the first fixing seat and the second fixing seat, especially the fixing at the step flange, to ensure that the first fixing seat provides support for the step flange during subsequent punching.

[0020] In order to avoid deformation of the thin step flange caused by the punching force, the blank adopts the form of the first end face facing vertically upward, the first fixed seat is used to support the radial outer end face of the step flange, and the driven punch is used to support the first pre-formed groove, such as Figure 3 As shown in the upper middle figure, the step flange will not be deformed by pressure.

[0021] The active punch enters from the second through hole, that is, from the second end face where the blank is thicker. The second end face has a thin wall formed by no step flange, so the deformation effect is small and it is suitable for the initial stage of entry. Figure 3 As shown in the middle and lower figures, the active punch punches to the first pre-formed groove, and the punched waste can enter the discharge hole of the driven punch, and push the driven punch back to the first through hole to complete the entire punching process. During the withdrawal process of the driven punch, it moves forward and backward in conjunction with the active punch, always maintaining support for the thin-walled step flange, and the active punch also gradually completes the punching of the first pre-formed groove, ensuring the consistency of the punching size.

[0022] The radial inward and outward support of the step flange by the driven punch and the first fixed seat minimizes the deformation effect of the punching pressure on the thin-walled part, and at the same time completes the one-time forming punching process of the inner hole of the thin-walled nut, improves the yield rate, avoids the additional drilling and boring process, and thus improves production efficiency and economic benefits.

[0023] At the same time, in the further process design, the maximum forging pressure of step 2 is set to 420T, the forging pressure of steps 1 and 3 are both designed to be 70% of the maximum forging pressure of step 2, that is, 294T, and steps 4 and 5 are respectively 70% of the forging pressure of the previous step, that is, step 4 is 205.8T, and step 5 is 144.06T. The purpose of this design is that the step is the shaping completion step, and the shaping is completed with the maximum forging pressure of the process. The forging pressure of the remaining steps decreases in sequence to match the gradual thinning and drilling of the nut blank, and avoid excessive forging pressure from damaging the blank size.

[0024] At the same time, it is difficult to clamp the workpiece with a clamp when using multi-station cold forging for very thin nuts. An electromagnetic clamp with an iron core inside is designed, which uses a coil with current to make it magnetic like a magnet. The iron core of the clamp should be made of soft iron or silicon steel that is easy to magnetize and easy to lose its magnetism. When the clamp is powered on, it is magnetic, and when the power is off, it disappears to facilitate clamping the workpiece. Electromagnetic clamps have many advantages: the presence or absence of electromagnetism can be controlled by turning on and off the current. The magnitude of magnetism can be controlled by the strength of the current or the number of turns of the coil. Working process: When the coil is powered on, the iron core and the armature are magnetized and become two magnets with opposite polarities. The electromagnetic attraction between them cooperates with the clamp to clamp the workpiece and align it with the mold cavity. When the workpiece is clamped, the part is locked in the clamp by magnetism. When the workpiece is pushed into the mold cavity, the armature begins to move toward the iron core. When the power supply is interrupted, the electromagnetic attraction is lost, and the armature will return to the original release position under the action of the reaction force. The electromagnetic clamp is a device that uses the electromagnetic attraction generated by the current-carrying iron core coil to manipulate the mechanical working device of the clamp to complete the expected action. It is an electromagnetic component assembly that converts electrical energy into mechanical energy. The electromagnetic clamp is mainly composed of three parts: coil, iron core and armature. The iron core and armature are generally made of soft magnetic materials. The iron core is generally stationary, and the coil is always installed on the iron core. The clamp generates magnetism through the power of electromagnetic and generates a large adsorption force. The use of booster cylinder to assist loosening can solve the problem of synchronous loosening of the clamp after demagnetization. The booster cylinder is used to control the input pressure change, and the hydraulic component with higher pressure output is used to loosen and clamp the clamp. The working process of the booster cylinder is to combine a hydraulic cylinder with a supercharger as an integral unit, and utilize the ratio of the cross-sectional areas of different sizes of the supercharger. Because the pressure remains unchanged, when the pressure area changes from large to small, the pressure will also change with the size, thereby achieving the effect of increasing the air pressure to dozens of times the pressure. Take the pre-pressurized booster cylinder as an example: when the working air pressure is pressed on the surface of the hydraulic oil (or piston), the hydraulic oil will compress the air and flow to the pre-pressurized stroke chamber. At this time, the hydraulic oil will quickly push the part to move. When the working displacement encounters resistance greater than the air pressure, the cylinder stops moving. At this time, the booster chamber of the booster cylinder is activated by the electrical signal (or pneumatic signal) and starts to increase the pressure to achieve the purpose of forming the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a nut structure diagram of an embodiment of the invention;

[0026] Figure 2 It is a schematic diagram of the process flow of cold heading of the blank front side according to the embodiment of the invention;

[0027] Figure 3 It is a schematic diagram of the process flow of cold heading of the reverse side of the blank according to the embodiment of the invention;

[0028] Figure 4 Cold heading process of the embodiment of the invention Figure 1 ;

[0029] Figure 5 Cold heading process of the embodiment of the invention Figure 2 ;

[0030] Figure 6 Cold heading process of the embodiment of the invention Figure 3 ;

[0031] Figure 7 It is a structural diagram of the electromagnet clamp according to an embodiment of the invention.

[0032] Among them, 1-blank, 11-first end face, 12-second end face, 13-first pre-formed groove, 14-second pre-formed groove, 15-hexagonal opposite sides, 16-pre-formed protrusion, 2-first fixed seat, 21-first mounting groove, 22-first through hole, 3-second fixed seat, 31-second mounting groove, 32-second through hole, 4-active punch, 5-driven punch, 51-discharge hole, 6-electromagnetic clamp, 61-pressure gauge, 62-boosting cylinder, 63-clamp, 64-coil, 7-step flange.

[0033] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. DETAILED DESCRIPTION

[0034] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be further described in detail in detail and in detail in conjunction with the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0035] The invention is described in detail below with reference to the accompanying drawings. Figure 1-7 As shown,

[0036] A cold forging process for a transmission locking nut, the process comprising the following steps: forming step 1: blanking a 40 mm diameter blank 1, the blank 1 comprising an axial first end face 11 and a second end face 12, rough forging the blank 1 to a 50 mm profile to form a chamfered truncated cone structure, and forging a first preformed groove 13 in the center of the first end face 11 of the blank 1;

[0037] Forming step 2: transfer the blank 1 to the next cold forging station, reverse 180° and forge to 55 mm, and forge a second pre-forming groove 14 at the center of the second end face 12 of the blank 1, and pre-form the hexagonal opposite sides 15 at the forging position on the outer peripheral surface of the blank 1 close to the second end face 12;

[0038] Forming step 3: the blank 1 is transferred to the next cold forging station, reversed 180 degrees, with the first end face 11 facing vertically upward, a preformed protrusion 16 is forged on the first end face 11, and a hexagonal opposite side 15 is forged on the outer peripheral surface of the blank 1 on the side of the second end face 12;

[0039] Forming step 4: transferring the blank 1 to the next cold heading station to complete the forming of the step flange 7;

[0040] Forming step 5: transferring the blank 1 to the next cold heading station for punching, the cold heading station at the punching location includes a first fixing seat 2, a second fixing seat 3, an active punch 4, and a driven punch 5, the second fixing seat 3 is provided with a second mounting groove 31 adapted to the contour of the hexagonal opposite side 15 on the second end face 12 of the blank 1, and the bottom of the second mounting groove 31 is coaxially provided with a second through hole 32 at the second pre-formed groove 14; the first fixing seat 2 is provided with a first mounting groove 21 adapted to the contour of the step flange 7 on the first end face 11 of the blank 1, and the first mounting groove 21 is provided with a first through hole 22 coaxial with the first pre-formed groove 13;

[0041] The driven punch 5 enters the first pre-forming groove 13 through the first through hole 22, and the outer peripheral surface of the driven punch 5 is slidably matched with the inner wall of the first pre-forming groove 13, and a discharge hole 51 is provided in the center;

[0042] The active punch 4 enters the second pre-forming groove 14 through the second through hole 32 to punch holes. When punching to the first pre-forming groove 13, the driven punch 5 is pushed out from the first through hole 22 to complete the cold heading of the nut.

[0043] The step 2 adopts the maximum forging pressure of 420T in the process, the forging pressures of steps 1 and 3 are both 70% of the maximum forging pressure of step 2, and the forging pressures of steps 4 and 5 are respectively 70% of the forging pressure of the previous step.

[0044] The first preformed groove and the second preformed groove are formed in a stepped shape with diameters decreasing toward the center.

[0045] The process adopts an electromagnet clamp 6 to clamp and deliver the blank 1 to each cold heading station; the electromagnet clamp includes a pressure gauge 61, a booster cylinder 62, a clamp 63, an iron core, an armature, and a coil 64. The coil 64 is energized to drive the iron core and the armature to be attracted, driving the clamp 63 to close and clamp the blank. The clamping force of the clamp 63 is controlled by the strength of the current or the number of turns of the coil 64, and the booster cylinder 62 drives the clamp to loosen.

[0046] As the instruction manual Figure 2-4 As shown, by gradually extending the diameter of the blank 1 to gradually reach the diameter size requirement, the blank 1 is reversed 180° twice, and pre-formed grooves are respectively upset on the first end face 11 and the second end face 12 to prepare for subsequent punching. At the same time, a pre-formed protrusion 16 is upset on the first end face 11, and finally formed into a step flange 7; a pre-formed contour of hexagonal opposite sides 15 is upset on the outer peripheral surface of the blank 1 on the side of the second end face 12, and finally the hexagonal opposite sides 15 are formed, thereby completing the outer contour structure of the nut of the present application.

[0047] Then the blank 1 is transferred to the cold heading station of the punching process, and the blank 1 is fixed by the first fixing seat 2 and the second fixing seat 3, especially the step flange 7, to ensure that the first fixing seat 2 provides support for the step flange 7 during subsequent punching.

[0048] In order to avoid deformation of the thin step flange 7 caused by the punching force, the blank 1 adopts the form of the first end face 11 facing vertically upward, the first fixing seat 2 is used to press against the radially outer end face of the step flange 7, and the driven punch 5 is used to press against the first preformed groove 13. Figure 3 As shown in the upper middle figure, the step flange 7 will not be deformed by pressure.

[0049] The active punch 4 enters from the second through hole 32, that is, from the second end face 12 of the blank 1, which is relatively thick. The second end face 12 has no thin wall formed by the step flange 7, and has little deformation effect, which is suitable for the initial stage of entry. Figure 3 As shown in the lower middle figure, the active punch 4 punches to the first preformed groove 13, and the punched waste can enter the discharge hole 51 of the driven punch 5, and push the driven punch 5 back to the first through hole 22 to complete the entire punching process. During the withdrawal process of the driven punch 5, it moves forward and backward in conjunction with the active punch 4, always maintaining support for the thin-walled step flange 7, and the active punch 4 also gradually completes the punching of the first preformed groove 13, ensuring the consistency of the punching size.

[0050] The radial inward and outward support of the driven punch 5 and the first fixed seat 2 on the step flange 7 minimizes the deformation effect of the punching pressure on the thin-walled part, and at the same time completes the one-time forming punching process of the inner hole of the thin-walled nut, improves the yield rate, avoids the additional drilling and boring process, and thus improves production efficiency and economic benefits.

[0051] At the same time, in the further process design, the maximum forging pressure of step 2 is set to 420T, the forging pressure of steps 1 and 3 are both designed to be 70% of the maximum forging pressure of step 2, that is, 294T, and steps 4 and 5 are respectively 70% of the forging pressure of the previous step, that is, step 4 is 205.8T, and step 5 is 144.06T. The purpose of this design is that the step is the shaping completion step, and the shaping is completed with the maximum forging pressure of the process. The forging pressure of the remaining steps decreases in sequence to match the gradual thinning and drilling of the nut blank, and avoid excessive forging pressure from damaging the blank size.

[0052] At the same time, it is difficult to clamp the workpiece with a clamp when using multi-station cold forging for very thin nuts. An electromagnetic clamp with an iron core inside is designed, which uses a coil with current to make it magnetic like a magnet. The iron core of the clamp should be made of soft iron or silicon steel that is easy to magnetize and easy to lose its magnetism. When the clamp is powered on, it is magnetic, and when the power is off, it disappears to facilitate clamping the workpiece. Electromagnetic clamps have many advantages: the presence or absence of electromagnetism can be controlled by turning on and off the current. The magnitude of magnetism can be controlled by the strength of the current or the number of turns of the coil. Working process: When the coil is powered on, the iron core and the armature are magnetized and become two magnets with opposite polarities. The electromagnetic attraction between them cooperates with the clamp to clamp the workpiece and align it with the mold cavity. When the workpiece is clamped, the part is locked in the clamp by magnetism. When the workpiece is pushed into the mold cavity, the armature begins to move toward the iron core. When the power supply is interrupted, the electromagnetic attraction is lost, and the armature will return to the original release position under the action of the reaction force. The electromagnetic clamp is a device that uses the electromagnetic attraction generated by the current-carrying iron core coil to manipulate the mechanical working device of the clamp to complete the expected action. It is an electromagnetic component assembly that converts electrical energy into mechanical energy. The electromagnetic clamp is mainly composed of three parts: coil, iron core and armature. The iron core and armature are generally made of soft magnetic materials. The iron core is generally stationary, and the coil is always installed on the iron core. The clamp generates magnetism through the power of electromagnetic and generates a large adsorption force. The use of booster cylinder to assist loosening can solve the problem of synchronous loosening of the clamp after demagnetization. The booster cylinder is used to control the input pressure change, and the hydraulic component with higher pressure output is used to loosen and clamp the clamp. The working process of the booster cylinder is to combine a hydraulic cylinder with a supercharger as an integral unit, and utilize the ratio of the cross-sectional areas of different sizes of the supercharger. Because the pressure remains unchanged, when the pressure area changes from large to small, the pressure will also change with the size, thereby achieving the effect of increasing the air pressure to dozens of times the pressure. Take the pre-pressurized booster cylinder as an example: when the working air pressure is pressed on the surface of the hydraulic oil (or piston), the hydraulic oil will compress the air and flow to the pre-pressurized stroke chamber. At this time, the hydraulic oil will quickly push the part to move. When the working displacement encounters resistance greater than the air pressure, the cylinder stops moving. At this time, the booster chamber of the booster cylinder is activated by the electrical signal (or pneumatic signal) and starts to increase the pressure to achieve the purpose of forming the product.

[0053] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A cold heading forming process for a transmission locking nut, characterized in that: The process comprises the following steps: forming step 1, cutting a blank with a diameter of 40 mm, the blank including a first end face and a second end face in the axial direction, rough upsetting the blank to a 50 mm profile, shaping it into a truncated cone structure with chamfers, and then upsetting a first pre-formed groove at the center of the first end face of the blank; Forming step 2, transferring the finished blank to the next cold forging station, turning it 180 degrees and forging it to 55 mm, and forging a second pre-forming groove in the center of the second end face of the blank, and preforming the hexagonal opposite sides at the forging on the outer peripheral surface of the blank close to the second end face; Forming step 3, transferring the blank to the next cold heading station, turning 180 degrees, with the first end face facing vertically upward, forging a preformed protrusion on the first end face, and forging a hexagonal opposite side on the outer peripheral surface of the blank on the second end face side; Forming step 4, transferring the blank to the next cold heading station, completing the step flange forming; Forming step 5, transferring the blank to the next cold heading station for punching, the cold heading station at the punching location includes a first fixing seat, a second fixing seat, an active punch, and a driven punch, the second fixing seat is provided with a second mounting groove adapted to the hexagonal opposite side contour of the second end face side of the blank, and the bottom of the second mounting groove is coaxially provided with a second through hole at the second pre-formed groove; the first fixing seat is provided with a first mounting groove adapted to the step flange contour of the first end face side of the blank, and the first mounting groove is provided with a first through hole coaxial with the first pre-formed groove; The driven punch enters the first pre-formed groove through the first through hole, the outer peripheral surface of the driven punch is slidably matched with the inner wall of the first pre-formed groove, and a discharge hole is provided in the center; The active punch enters the second pre-formed groove from the second through hole to punch a hole, and when punching to the first pre-formed groove, the driven punch is pushed out from the first through hole to complete the cold heading of the nut; The step 2 adopts the maximum forging pressure of 420T in the process, the forging pressures of steps 1 and 3 are both 70% of the maximum forging pressure of step 2, and steps 4 and 5 are respectively 70% of the forging pressure of the previous step; The first preformed groove and the second preformed groove are formed in a stepped shape with diameters decreasing toward the center.

2. The cold heading forming process for a transmission locking nut according to claim 1, characterized in that: The process adopts an electromagnetic clamp to clamp and deliver the blank to each cold heading station; the electromagnetic clamp includes a pressure gauge, a booster cylinder, a clamping jaw, an iron core, an armature, and a coil. The coil is energized to drive the iron core and the armature to be attracted, driving the clamping jaw to close and clamp the blank. The clamping force of the clamping jaw is controlled by the strength of the current or the number of turns of the coil, and the booster cylinder drives the clamping jaw to loosen.

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