Method and die for forging and forming hollow shaft blank plate with unequal wall thickness

Abstract

The invention discloses an unequal-wall-thickness hollow type shaft blank plate forging die which comprises an upper die part and a lower die part, the invention further provides an unequal-wall-thickness hollow type shaft blank plate forging forming method, and compared with a traditional method, the unequal-wall-thickness hollow type shaft blank plate forging die is high in size precision and low in production cost, and the material utilization rate is increased. The method comprises the specific steps that firstly, a pipe blank is placed in a female die, then a sliding block on the outer side of a press vertically moves downwards to drive a male die to extrude the blank, the middle wall thickness is reduced, the lower end part is freely formed and necked towards the middle, and a hollow shaft blank with the unequal wall thickness is obtained; and finally, the press machine outer sliding block vertically moves upwards to enable the workpiece to be separated from the upper die, and the ejector rod ejects out to complete workpiece taking.

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 unequal wall thickness. Background Art

[0002] Compared with solid shafts, hollow shafts with the same outer diameter have little difference in transmitting torque, bending moment and combined bending moment functions, but can meet the requirements of lightweight. Moreover, hollow motor shaft parts are no longer satisfied with the requirements of equal wall thickness. Parts with the same wall thickness may have a series of problems such as high weight, excessive local structural stiffness and strength performance, which brings new challenges to the field of metal plastic forming.

[0003] At present, people use rotary forging and spinning to form hollow shaft blanks with different wall thicknesses. However, rotary forging equipment is expensive, the production cost is high, and it is not suitable for small batch production. At the same time, there is a problem of low precision after spinning.

[0004] Therefore, how to change the current situation in the prior art where the forming cost of hollow shaft blanks with unequal wall thicknesses is high and the precision is poor has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In order to solve the shortcomings of existing technologies, the present invention proposes a forging method and mold for hollow shaft blanks with unequal wall thicknesses, which can achieve differentiated distribution of the wall thickness of the hollow shaft blanks in one process, while saving costs and improving precision.

[0006] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a forging forming die for hollow shaft blanks with unequal wall thickness, characterized in that it includes an upper die part and a lower die part; the upper die part is composed of a punch, a detachable core, an upper die fixing plate, an upper pad, and an upper die seat; the lower die part is composed of a die, a lower die fixing plate, a lower pad, a lower die seat, and a push rod; the upper die fixing plate, the upper pad, and the upper die seat are connected by screws to form a whole, and their movement is controlled by a press slider; the lower die fixing plate is connected to the pad, and the pad is connected to the lower die seat with screws; the detachable core is installed inside the punch and the two are coaxially arranged without relative sliding, and the outer diameter of the detachable core corresponds to the aperture of the blank; there is a gap between the die and the punch; the inner size of the die needs to match the shape of the blank.

[0007] Preferably, the forming punch and the outer die, as well as the forming punch and the detachable core, adopt clearance fit; the forming punch and the outer die adopt H7 / g6 fit, and the forming punch and the detachable core adopt H6 / h5 fit.

[0008] Preferably, the taper angle of the upper end of the die should ensure that α=150°, and the gap between the maximum inner diameter of the die and the detachable core is .

[0009] Preferably, the taper angle at the lower end of the die should be β=157°, and the clearance between the inner diameter of the middle part of the two taper angles of the die and the detachable core should be .

[0010] Preferably, the diameter of the minimum inner diameter of the die should ensure .

[0011] The present invention also provides a forging method for a hollow shaft blank with unequal wall thickness, using the above-mentioned forging die for a hollow shaft blank with unequal wall thickness, comprising the following steps: Step (1) transferring a tubular blank of equal wall thickness to a die and positioning it based on the outer contour of the blank, and the outer slide of the press moves vertically downward to drive the punch to extrude the blank, so that the blank is squeezed into a semi-enclosed area formed by the die and the detachable core, so that the tube wall is thinned; Step (2) the punch continues to move downward, causing the metal to flow into the die with a smaller diameter, allowing the lower end of the blank to shrink freely, and finally forming a hollow shaft blank metal part with different outer diameters, different inner diameters and different wall thicknesses; Step (3) The outer slide of the press drives the punch to move vertically upward and separate from the workpiece, and the ejector pin ejects the workpiece upward, completing the removal of the workpiece.

[0012] Technical effect: The present invention forms a hollow shaft blank with unequal wall thicknesses at one time, effectively solving the problem of multiple extrusion processes, improving the dimensional accuracy and mechanical properties of the target parts, and has the advantages of simple process, low forming load and high forming accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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 drawings in the following description are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0014] Figure 1 It is a schematic diagram of the cross-section structure of the hollow shaft blank forging die of unequal wall thickness of the present invention when it is working; Figure 2 A schematic diagram of a tube blank formed by the forging forming method of a hollow shaft blank with unequal wall thickness according to the present invention; Figure 3 A schematic diagram of a target part formed by the forging forming method of a hollow shaft blank with unequal wall thickness according to the present invention; In the figure, upper die base 1, upper die pad 2, upper die fixing plate 3, punch 4, detachable core 5, die 6, lower die fixing plate 7, lower pad 8, lower die base 9, screw 10, screw 11, screw 12, screw 13, and push rod 14. is the outer diameter of the tube, is the wall thickness of the tube, is the height of the tube, is the outer diameter of the thinned part in the middle of the target part, is the wall thickness of the thinned part in the middle of the target part, is the outer diameter of the free shrinkage at the lower end of the target part, is the maximum wall thickness of the free shrinkage at the lower end of the target part, is the height of the target part, and α and β are the taper angles of the die. DETAILED DESCRIPTION

[0015] 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.

[0016] The purpose of the present invention is to provide a forging die for a hollow shaft blank with unequal wall thickness, so as to solve the problems existing in the above-mentioned prior art, improve the dimensional accuracy and mechanical properties of the formed parts, and reduce the production cost.

[0017] 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.

[0018] Please refer to Figure 1-3 ,in, Figure 1 It is a schematic diagram of the cross-section structure of the hollow shaft blank forging die of unequal wall thickness of the present invention when it is working. Figure 2 A schematic diagram of a tube blank formed by the forging forming method of a hollow shaft blank with unequal wall thickness according to the present invention; Figure 3 It is a schematic diagram of a target part formed by the forging forming method of hollow shaft blank with unequal wall thickness of the present invention.

[0019] like Figure 1As shown, the present invention provides a forging forming die for hollow shaft blanks with unequal wall thickness, including an upper die part and a lower die part; the upper die part is composed of a punch 4, a detachable core 5, an upper die fixing plate 3, an upper pad 2, and an upper die seat 1; the lower die part is composed of a die 6, a lower die fixing plate 7, a lower pad 8, a lower die seat 9, and a push rod 14; the upper die fixing plate 3, the upper pad 2, and the upper die seat 1 are connected by screws to form a whole, and their movement is controlled by a press slide; the lower die fixing plate 7 is connected to the pad 8 by screws 12, and the pad 8 is connected to the lower die seat 9 by screws 13; the detachable core 5 is installed inside the punch 4 and the two are coaxially arranged without relative sliding, and the outer diameter of the detachable core 5 corresponds to the hole diameter of the blank; the inner size of the die 6 needs to match the shape of the blank.

[0020] The present invention also provides a method for forging a hollow shaft blank with unequal wall thickness, comprising the following steps: Step 1: Set the outer diameter to , wall thickness is , height is The tube is positioned according to its outer diameter and placed in the forming die 7. The main cylinder of the press has an independent slider output mechanism. The punch is connected to the slider in the main cylinder of the press. As the slider drives the punch to slide down at a uniform speed to extrude the upper end surface of the tube blank, the blank is squeezed into the semi-enclosed area composed of the die and the detachable core shaft, so that the tube wall is thinned.

[0021] Step 2: The slider in the main cylinder of the press drives the punch to continue to shape, so that the metal flows into the smaller diameter die, so that the lower end of the blank can shrink freely to form the target part, such as Figure 3 As shown, the outer diameter of the thinned part in the middle of the target part is , the wall thickness of the middle thinning part is , the maximum outer diameter of the free shrinkage at the lower end is , the maximum wall thickness of the free shrinkage at the lower end is , height is , the two cone angles are α and β respectively.

[0022] Step 3: After the part is formed, during the demolding process, the press slide drives the punch back to separate from the part, and then the hydraulic cylinder under the press drives the ejector device to eject the part out of the die.

[0023] In this specific embodiment, the forming punch and the outer die, the forming punch and the detachable core are all clearance matched; the forming punch and the outer die are matched with H7 / g6, and the forming punch and the detachable core are matched with H6 / h5. In addition, the taper angle of the upper end of the die should ensure that α=150°, and the clearance between the maximum inner diameter of the die and the detachable core is .

[0024] In addition, the taper angle of the lower end of the die should ensure β = 157°, and the gap between the inner diameter of the middle part of the two taper angles of the die and the detachable core should ensure .

[0025] In this specific embodiment, the outer diameter of the minimum outer diameter of the die should ensure .

[0026] The present invention forms a hollow shaft blank with unequal wall thicknesses at one time, effectively solves the problem of multiple extrusion processes, improves the dimensional accuracy and mechanical properties of the target parts, and has the advantages of simple process, low forming load and high forming accuracy.

[0027] 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 hollow shaft blanks with unequal wall thicknesses, which utilizes a forging die for hollow shaft blanks with unequal wall thicknesses to form shaft blanks with equal wall thicknesses and different inner diameters, characterized in that: The mold comprises an upper mold part and a lower mold part; the upper mold part comprises a punch, a detachable core, an upper mold fixing plate, an upper pad, and an upper mold seat; the lower mold part comprises a die, a lower mold fixing plate, a lower pad, a lower mold seat, and a push rod; the upper mold fixing plate, the upper pad, and the upper mold seat are connected by screws to form a whole, and their movement is controlled by a press slide; the lower mold fixing plate is connected to the pad, and the pad is connected to the lower mold seat by screws; the detachable core is installed inside the punch and the two are coaxially arranged without relative sliding, and the outer diameter of the detachable core corresponds to the inner diameter of the tube blank; there is a gap between the die and the punch, and the inner size of the die needs to match the shape of the blank; the forming method comprises the following steps: Step 1: Transfer the blank of the tubular structure with equal wall thickness to the die and position it according to the outer contour of the blank. The outer slide of the press moves vertically downward to drive the punch to extrude the blank, so that the blank is squeezed into the semi-enclosed area composed of the die and the detachable core, so that the tube wall is thinned; Step 2: The punch continues to move downward, so that the metal flows into the die with a smaller diameter, so that the lower end of the blank is freely shrunken, and finally a hollow shaft blank metal part with different wall thicknesses and different inner diameters is formed; Step 3: The outer slide of the press moves vertically upward to separate the punch from the workpiece, and the ejector pin ejects the workpiece upward.

2. The method for forging a hollow shaft blank with unequal wall thickness according to claim 1, characterized in that: The forming punch and the outer die, as well as the forming punch and the detachable core, all adopt clearance fit; the forming punch and the outer die adopt H7 / g6 fit, and the forming punch and the detachable core adopt H6 / h5 fit.

3. The method for forging a hollow shaft blank with unequal wall thickness according to claim 1, characterized in that: The taper angle of the upper end of the die should be α = 150°, and the gap between the maximum inner diameter of the die and the detachable core is .

4. The method for forging a hollow shaft blank with unequal wall thickness according to claim 1, characterized in that: The taper angle at the lower end of the die should be β = 157°, and the clearance between the inner diameter of the middle part of the two taper angles of the die and the removable core should be .

5. The method for forging a hollow shaft blank with unequal wall thickness according to claim 1, characterized in that: The diameter of the minimum inner diameter of the die should ensure .

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