Forging forming method and die for hollow shaft blank plate with outer flange characteristic

Abstract

The invention belongs to the field of advanced forming manufacturing and plastic processing, and provides a hollow shaft blank plate forging forming die with an outer flange characteristic, which comprises an upper die holder, a shearing and extruding convex die, a floating concave die, a floating core shaft, an outer side concave die, an ejector rod, a nitrogen spring, a base plate and a lower die holder. The invention further provides a forging forming method for the hollow shaft blank plate with the outer flange characteristic, and the forging forming method utilizes the forging forming die for the hollow shaft blank plate with the outer flange characteristic and comprises the following steps that firstly, a pipe meeting the needed part size is obtained; secondly, a blank with the outer flange characteristic and the needed part appearance is formed through the mold; and thirdly, the hollow shaft blank is subjected to one-time machining, and the hollow shaft is formed. According to the method, the plate forging technology is applied to the hollow shaft, and on the premise that the performance is met, the forming load is greatly reduced, the manufacturing cost is reduced, the service life of a forming die is prolonged, and the core competitiveness of a product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal plastic forming, in particular to a forging method and a die for a hollow shaft blank with an external flange feature. Background Art

[0002] With the rapid development of new energy vehicles, the weight of automotive parts such as motor shafts must be reduced due to the limitation of driving range, and the solid shafts on traditional vehicles can no longer meet the requirements of lightweight manufacturing of automobiles, so hollow shafts came into being. The characteristics of this type of hollow shaft are that the height-to-diameter ratio is greater than or equal to 2, the wall thickness of the middle part is less than or equal to 10mm, and there is an external flange feature at one end of the shaft.

[0003] At present, people generally use machining, rotary forging and traditional cold forging methods to form hollow motor shafts with external flange features, but the machining allowance is large, especially for such hollow shafts with external flange features, not only the inner wall needs to be drilled, but the outer wall also needs to be machined when forming the outer flange, resulting in low material utilization, high cost and no competitive advantage for the product; rotary forging equipment occupies a large area, is expensive and is not suitable for small batch production; traditional cold forging methods have large forming force, short die life, and are prone to defects such as folding and cracking.

[0004] Therefore, how to change the current situation in which it is difficult to form a hollow shaft blank with an external flange feature has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a hollow shaft blank forging forming die with an external flange feature to solve the problems existing in the above-mentioned prior art and improve the competitive advantage of existing products.

[0006] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a hollow shaft blank forging forming die with an external flange feature, comprising an upper die seat, a shearing punch, a floating die, a floating mandrel, an outer die, a push rod, a nitrogen spring, a pad, and a lower die seat. The shearing punch, the floating die, the outer die, the push rod, the pad, and the floating mandrel are coaxially placed between the upper and lower die seats, the nitrogen springs are evenly distributed on the outer die to ensure the force balance of the floating die, the floating die and the outer die are connected by the nitrogen spring, and the The bottom of the outer die and the floating mandrel slide against each other, and the floating die is slidably connected to the outer die, wherein there is a gap between the outer die and the floating mandrel, the lower end gap ensures relative sliding, and the upper end gap ensures the wall thickness of the pipe, there is a gap between the shearing punch and the outer die and the floating mandrel, there is a gap between the push rod and the lower die seat and the pad, the nitrogen spring is the limiting element of the floating die, the limiting element of the shearing punch is the limiting block on the press, and the connecting and positioning elements are screws and pins.

[0007] Preferably, the fillet radius of the working portion of the upper end of the floating mandrel should be between 0.1 mm and 5 mm.

[0008] Preferably, the minimum height between the shearing punch and the floating die should be ensured to be greater than the height of the outer flange of the target part.

[0009] The present invention also provides a method for forging a hollow shaft blank with an external flange feature, using the above-mentioned hollow shaft blank with an external flange feature forging die, comprising the following steps:

[0010] Step 1: Obtain the pipe that meets the required part size;

[0011] Step 2: using the above mold to form a blank with the required part shape having the characteristics of an outer flange;

[0012] Step 3: Machining the hollow shaft blank once to form the hollow shaft.

[0013] Preferably, in step 1, obtaining a tube that meets the required parts should first include drilling, turning or drawing the rod to ensure uniform wall thickness, and the height-to-diameter ratio of the tube should be greater than 2:1.

[0014] Preferably, in step 2, the stroke of the shearing punch should be greater than the maximum relative distance between the floating die and the outer die.

[0015] Compared with the prior art, the present invention has achieved the following technical effects: the present invention provides a hollow shaft blank forging forming die with an external flange feature, comprising an upper die seat, a shearing punch, a floating die, a floating mandrel, an outer die, a push rod, a nitrogen spring, a pad, and a lower die seat, wherein the shearing punch, the floating die, the outer die, the push rod, the pad, and the floating mandrel are coaxially placed between the upper and lower die seats, the nitrogen springs are uniformly distributed on the outer die to ensure the force balance of the floating die, the floating die and the outer die are connected by the nitrogen spring, and the The bottom of the outer die and the floating mandrel slide against each other, and the floating die is slidably connected to the outer die, wherein there is a gap between the outer die and the floating mandrel, the gap at the lower end ensures relative sliding, and the gap at the upper end ensures the wall thickness of the pipe, there is a gap between the shearing punch and the outer die and the floating mandrel, there is a gap between the push rod and the lower die seat and the pad, the nitrogen spring is the limiting element of the floating die, the limiting element of the shearing punch is the limiting block on the press, and the connecting and positioning elements are screws and pins. The present invention also provides a forging forming method for a hollow shaft blank with an external flange feature, the first step is to obtain a pipe that meets the required parts; the second step is to place the machined parts in the above-mentioned mold to form the required part shape with the external flange feature; the third step is to machine the hollow shaft blank once to form a hollow shaft. The present invention also has the following advantages:

[0016] (1) By adopting the above process steps, a hollow shaft that meets the requirements can be manufactured, that is, the wall thickness, aspect ratio, diameter and height of the outer flange and the tolerance of the tube blank all meet the requirements of the hollow shaft, and compared with the traditional processing technology, the above process greatly reduces the processing steps of the parts during processing, improves processing efficiency, shortens the processing cycle, and at the same time improves the utilization rate of related materials, saves processing costs, and improves product competitiveness.

[0017] (2) Through the above process steps, a hollow shaft with an external flange feature can be produced, and the mechanical properties and other indicators can meet the requirements of parts produced by traditional forging methods. In particular, the flange area is deformed by shearing and extrusion, and the strength meets the characteristics of the hollow shaft that can withstand high speed and alternating loads.

[0018] (3) By using this die to form the hollow shaft blank after preliminary processing, the folding defects caused by the nitrogen spring stroke during the forming process can be effectively improved, and the number and tonnage of nitrogen springs required can be directly reduced. Since the contact area between the shearing punch and the pipe is small, the forming force is stable and far less than the forming force required by the traditional forging forming method, which greatly increases the life of the die. The inner hole and outer circle of the formed part have high shape and position accuracy. After forming, all inner holes except those with assembly requirements can be left unprocessed, which greatly saves machining costs and improves product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic cross-sectional structure diagram of a hollow shaft blank forging forming die with an external flange feature of the present invention when it is working;

[0021] Figure 2 It is a schematic diagram of the cross-sectional structure of the pipe material required for step 1 of a hollow shaft blank forging forming method with an external flange feature of the present invention;

[0022] Figure 3 It is a schematic diagram of the cross-sectional structure of the hollow shaft blank after being formed by a die in step 2 of a forging method of a hollow shaft blank with an external flange feature of the present invention;

[0023] Figure 4 It is a schematic diagram of the cross-sectional structure of the hollow shaft blank after machining in step 3 of a forging forming method of a hollow shaft blank with an external flange feature of the present invention;

[0024] Among them, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are respectively the upper die base, shearing punch, floating die, floating mandrel, outer die, ejector rod, nitrogen spring, pad, and lower die base; D is the outer diameter of the pipe required in step one, H is the height of the pipe, and L is the wall thickness of the pipe; H1 is the minimum height between the shearing punch and the floating die in step two, L1 is the shearing depth of the shearing punch, and r is the fillet radius of the lower end of the inner wall of the shearing punch; H2 is the height of the outer flange of the target part in step three; t1 and t2 are two different thicknesses of the side wall of the end of the target part. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The purpose of the present invention is to provide a hollow shaft blank forging forming die with an external flange feature to solve the problems existing in the above-mentioned prior art and improve the competitiveness of existing products.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Please refer to Figure 1-4 ,in, Figure 1 It is a schematic diagram of the cross-section structure of a hollow shaft blank forging forming die with an external flange feature of the present invention when it is working. Figure 2 This is a schematic diagram of the cross-sectional structure of the pipe required for step 1 of a hollow shaft blank forging method with an external flange feature of the present invention. Figure 3 This is a schematic diagram of the cross-sectional structure of the hollow shaft blank after being formed by a die in step 2 of a forging method for a hollow shaft blank with an external flange feature of the present invention. Figure 4 It is a schematic diagram of the cross-sectional structure of the hollow shaft blank after machining in step three of a forging forming method for a hollow shaft blank with an external flange feature of the present invention.

[0029] The present invention provides a hollow shaft blank forging forming die with an external flange feature, comprising an upper die base 1, a shearing punch 2, a floating die 3, a floating mandrel 4, an outer die 5, a push rod 6, a nitrogen spring 7, a pad 8, and a lower die base 9. The shearing punch 2, the floating die 3, the floating mandrel 4, the outer die 5, the push rod 6, and the pad 8 are coaxially placed between the upper die base 1 and the lower die base 2. The nitrogen springs 7 are evenly distributed on the lower die base 9 to ensure that the floating die 3 is balanced in force. The floating die 3 is placed on the nitrogen spring 7, and the push rod 6 is placed in the pad 8. The floating mandrel 4 is placed on the top of the pad 8, and the floating die 3 is slidably connected to the outer die 5, wherein there is a gap between the floating die 3 and the floating mandrel 4, the lower end gap ensures relative sliding, and the upper end gap ensures the wall thickness of the pipe, there is a gap between the shearing punch 2 and the outer die 5 and the floating mandrel 4, there is a gap between the push rod 6 and the lower die base 9 and the pad 8, the nitrogen spring 7 is a limiting element of the floating die 3, the limiting element of the shearing punch 2 is a limiting block on the press, and the connecting and positioning elements are screws and pins.

[0030] In addition, the fillet radius of the upper working portion of the floating die 3 should be between 0.1 mm and 5 mm; the minimum height H1 between the shearing punch 2 and the floating die 3 should be at least greater than the outer flange height H2 of the target part.

[0031] The present invention also provides a method for forging a hollow shaft blank with an external flange feature, using the above-mentioned hollow shaft blank with an external flange feature forging die, comprising the following steps:

[0032] Step 1: Obtain pipes that meet the required parts;

[0033] Step 2: using the above mold to form a blank with the required part shape having the characteristics of an outer flange;

[0034] Step 3: Machining the hollow shaft blank once to form the hollow shaft.

[0035] Specifically, in step one, the step of obtaining a tube that meets the required part shape includes extruding or drawing the original rod and inspecting the chemical composition, structure, mechanical properties and defects of the material, verifying whether the tube after extrusion or drawing and heat treatment meets the requirements of the part, and selecting the required tube according to the verification result, and the tube height-to-diameter ratio H / D is greater than or equal to 2:1.

[0036] In step 2, the above-mentioned mold is used to form a blank with the required part shape with the characteristics of the outer flange, which specifically includes the following steps: during forming, the outer die 5 and the floating mandrel 4 are positioned, the nitrogen springs 7 are evenly distributed on the outer die 5, the floating die 3 is placed above the spring 7 and can slide relative to the outer die 5, and then the blank is placed on the floating mandrel 4, and the oil cylinder pushes the shearing punch 2 downward to form the part; after forming, the floating mandrel 4 is pushed out by the ejector rod. Among them, the single-sided gap between the pipe and the floating die 3 and the floating mandrel 4 should be between 0.05mm and 0.1mm, and the stroke of the shearing punch 2 should be greater than the maximum relative distance between the floating die 3 and the outer die 5. The whole process uses a single-cylinder press, which has simple equipment, few processes, is suitable for mass production, and has a strong product competitive advantage.

[0037] In step three, the hollow shaft blank is machined once to form the hollow shaft, which should include machining of the outer flange area, and may also include machining of the inner wall, outer circle, step, undercut and / or spline.

[0038] The present invention provides a forging method and die for a hollow shaft blank with an external flange feature, which has the following advantages:

[0039] (1) By adopting the above process steps, a hollow shaft that meets the requirements can be manufactured, that is, the wall thickness, aspect ratio, diameter and height of the outer flange and the tolerance of the tube blank all meet the requirements of the hollow motor shaft. Compared with the traditional processing technology, the above process greatly reduces the processing steps of parts during processing, improves processing efficiency, shortens the processing cycle, and at the same time improves the utilization rate of related materials, saves processing costs, and improves product competitiveness.

[0040] (2) Through the above process steps, a hollow shaft with a local external flange feature can be produced, and the mechanical properties and other indicators can meet the requirements of parts produced by traditional forging methods. In particular, the flange area is deformed by shearing and extrusion, and the strength meets the requirements of the hollow motor shaft to withstand high speed and alternating loads.

[0041] (3) By using this die to form the hollow shaft blank after preliminary processing, the folding defects formed at the height of the nitrogen spring during the forming process can be effectively improved, and the number and tonnage of nitrogen springs required can be directly reduced. Since the contact area between the shearing punch and the pipe is small, the forming force is stable and far less than the forming force required by the traditional forging forming method, which greatly increases the life of the die. The inner hole and outer circle of the formed part have high shape and position accuracy. After forming, all inner holes except those with assembly requirements can be left unprocessed, which greatly saves machining costs and improves product competitiveness.

[0042] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for forging a hollow shaft blank with an external flange feature, using a hollow shaft blank with an external flange feature forging die, can produce a hollow shaft blank with an external flange feature without folding or buckling defects, characterized in that: The mold comprises an upper die seat, a shearing punch, a floating die, a floating mandrel, an outer die, a push rod, a nitrogen spring, a pad, and a lower die seat. The shearing punch, the floating die, the floating mandrel, the outer die, the push rod and the pad are coaxially placed between the upper die seat and the lower die seat. The nitrogen springs are evenly distributed on the lower die seat. The floating die is placed on the nitrogen spring. The push rod is placed in the pad. The floating mandrel is placed on the top of the pad. The floating die is slidably connected to the outer die. There is a gap between the floating die and the floating mandrel. The gap at the lower end ensures relative sliding, and the gap at the upper end ensures the wall thickness of the pipe. There is a gap between the shearing punch and the outer die and the floating mandrel. There is a gap between the push rod and the lower die seat and the pad. The nitrogen spring is a limiting element of the floating die. The limiting element of the shearing punch is a limiting block on the press. The connecting and positioning elements are screws and pins. The forming method comprises the following steps: Step 1: Obtain pipes that meet the required parts; Step 2: Use the above mold to form a blank with the required part shape and external flange features. Step 3: machining the hollow shaft blank to form the hollow shaft.

2. The method for forging a hollow shaft blank with an external flange feature according to claim 1, characterized in that: The minimum height between the shearing punch and the floating die should be ensured to be greater than the height of the outer flange of the target part.

3. The method for forging a hollow shaft blank with an external flange feature according to claim 1, characterized in that: In step 1, the height-to-diameter ratio of the tube is greater than 2:

1.

4. The method for forging a hollow shaft blank with an external flange feature according to claim 1, characterized in that: In the step 2, the stroke of the shearing punch should be greater than the maximum relative distance between the floating die and the outer die.

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