Design method of cold extrusion die with adjustable spline parameters

Abstract

The invention provides a design method of a spline parameter-adjustable cold extrusion die, which comprises the following steps: S1, pressing an accommodated part into a second accommodating cavity, and forming a combined part by the accommodated part and a middle sleeve; and S2, the assembly is pressed into the first containing cavity, and the rod spacing of the tooth part is adjusted by adjusting the length of the part, pressed into the first containing cavity, of the assembly or changing the tolerance fit interference magnitude of the first containing cavity and the assembly. The method has the beneficial effects that the design process is simple, the press-in method is adopted, the actual error in machining can be compensated by calculating the target given value to finely adjust spline parameters, and rod spacing mold inventory of various gears can be established on the premise that the product size requirement is met.

Description

Technical Field

[0001] This invention relates to the field of metal compact forging technology, and in particular to a design method for a cold extrusion die with adjustable spline parameters. Background Technology

[0002] Cold extrusion spline processing is a non-cutting machining process that not only boasts high production efficiency, high material utilization, strong spline load-bearing capacity, and low production cost, but also maintains continuous metal flow lines within the spline, resulting in varying degrees of grain breakage and elongation. During subsequent heat treatment, the grains are further refined, thereby improving the overall mechanical properties of the part. The tooth profile accuracy of the spline shaft is determined by the cold extrusion die (i.e., the concave die).

[0003] When machining a die, a wire EDM machine is typically used to machine the internal tooth shape of the die. During wire EDM, the tooth surface is usually machined multiple times, with a certain amount of grinding and polishing allowed. However, the finished die is generally difficult to meet the dimensional requirements of certain products in one go, and the dimensions cannot be adjusted again. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to provide a design method for a cold extrusion die with adjustable spline parameters, which can make minute adjustments to the spline parameters to compensate for actual machining errors and reduce the defect rate in die manufacturing.

[0005] This invention provides a design method for a cold extrusion die with adjustable spline parameters. The cold extrusion die includes: an enclosure member having a through first receiving cavity; an intermediate sleeve having an interference fit within the first receiving cavity, the intermediate sleeve including an outer conical surface contacting the inner wall of the first receiving cavity and a through second receiving cavity; and an enclosure member having an interference fit within the second receiving cavity, having a through toothed extrusion cavity, the inner wall of the toothed extrusion cavity having teeth for forming external splines.

[0006] The design method includes the following steps:

[0007] S1. Press the enclosed member into the second receiving cavity, and the enclosed member and the intermediate sleeve form an assembly;

[0008] S2. Press the assembly into the first receiving cavity, and adjust the bar spacing of the teeth by adjusting the length of the assembly pressed into the first receiving cavity, or by changing the tolerance fit interference between the first receiving cavity and the assembly.

[0009] Preferably, in step S2, the range of values ​​for the tolerance fit interference is obtained through the following steps:

[0010] The minimum interference required to transfer the load can be calculated using the formula in Table 1:

[0011] Table 1

[0012]

[0013]

[0014] The maximum effective interference fit that allows for no plastic deformation in a conical interference fit can be calculated using the formulas in Table 2:

[0015] Table 2

[0016]

[0017] Preferably, the average cone diameter d of the mating surface m Obtained through equation (1):

[0018]

[0019] Where: d f2 C is the maximum cone diameter of the mating surface, and C is the taper of the mating surface.

[0020] Preferably, the method further includes step S3:

[0021] S3. Assemble the pad block in the first receiving cavity. The pad block is located below the assembly and has a through hole that communicates with the toothed extrusion cavity.

[0022] The advantages of this invention are that the design process is simple, the press-fit method can be used to make minor adjustments to the spline parameters by calculating the target given value to compensate for the actual error in machining, and it can establish a stock of bar spacing molds for various positions while meeting product size requirements. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cold extrusion die of the present invention;

[0024] Figure 2 This is a schematic diagram showing the displacement of the involute spline in the tooth section under extrusion.

[0025] Component designation explanation:

[0026] 1 Enclosure

[0027] 2. Intermediate Set

[0028] 3 Enclosed Items

[0029] 31 Toothed extrusion chamber

[0030] 32 teeth

[0031] 4 spacers

[0032] 41 Through hole Detailed Implementation

[0033] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] In the description of this invention, it should be noted that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 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 invention according to the specific circumstances.

[0036] Figure 1 The diagram shown is a structural schematic of the cold extrusion die of the present invention. In the following description, it will be referred to as... Figure 1 The attached diagram serves as a reference for direction. Figure 1 In the view, the direction upwards along the paper is called the up direction, and the direction downwards along the paper is called the down direction.

[0037] like Figure 1 As shown, the cold extrusion die designed in this invention includes an enclosing member 1, an intermediate sleeve 2, and an enclosed member 3. The enclosing member 1 has a first receiving cavity that extends vertically. The intermediate sleeve 2 is press-fitted into the first receiving cavity, and the intermediate sleeve 2 includes an outer conical surface that contacts the inner wall of the first receiving cavity, and also has a second receiving cavity that extends vertically. Specifically, the first and second receiving cavities are cylindrical through holes. The enclosed member 3 is press-fitted into the second receiving cavity, which has a toothed extrusion cavity 31 that extends vertically. The inner wall of the toothed extrusion cavity 31 has teeth 32 for forming external splines. The shaft to be extruded into the toothed extrusion cavity 31 is extruded from top to bottom, thus completing the extrusion forming of the external spline.

[0038] This invention provides a design method for a cold extrusion die with adjustable spline parameters, the design method comprising the following steps:

[0039] S1. Press the enclosed part 3 into the second receiving cavity, and the enclosed part 3 and the intermediate sleeve 2 form an assembly.

[0040] S2. Press the assembly into the first receiving cavity to form a conical interference fit connection. Adjust the length of the assembly pressed into the first receiving cavity, or change the tolerance fit interference between the first receiving cavity and the assembly to adjust the bar spacing of the teeth 32.

[0041] S3. Assemble the spacer block 4 into the first receiving cavity. The spacer block 4 is located below the assembly and has a through hole 41 that connects to the toothed extrusion cavity 31. After assembling the spacer block 4 into the first receiving cavity 4, the assembly can be leveled. The cold extrusion die assembly is complete. The shaft with external splines can then exit the cold extrusion die through the through hole 41, ultimately obtaining a splined shaft.

[0042] Combination Figure 2 As can be seen, the design principle of this invention is as follows:

[0043] Adjusting the interference fit between the assembly and the housing 1 causes deformation of the housing 3, shifting its internal profile inward by a certain amount, resulting in a displacement of the involute spline of the tooth section 32. After displacement, the tooth profile of the internal spline belongs to the same involute as the standard spline, but its application section is different, thus obtaining a good involute section and improving spline parameters. The change in the pitch M of the tooth section 32 indirectly reflects the displacement of the internal spline. Since the limit deviation of the pitch M can be derived from the limit deviation of the tooth space width of the pitch circle of the internal spline, as long as the measured length of the pitch M is within its required tolerance, the tooth thickness and tooth space width of the internal spline are also within their tolerances; they are in a one-to-one correspondence.

[0044] In step S2, the calculation conditions, key points, calculation targets, and known conditions for tolerance fit interference are as follows:

[0045] Calculation conditions: The enclosing member 1 and the enclosed member 3 are in a plane stress state, that is, the axial stress is 0; the joint pressure of the enclosing member 1 and the enclosed member 3 along the joint length is constant; the elastic modulus of the material is constant; the strength calculation is based on the deformation energy theory.

[0046] Calculation points: The calculation of the conical surface interference connection is the same as that of the cylindrical surface interference connection specified in GB5371, that is, the joint diameter d f The average cone diameter d of the mating surface should be used. m replace:

[0047]

[0048] Calculation targets: Enclosing part 1 and intermediate sleeve 2 are made of H13 mold steel with a hardness of 48-52HRC; enclosed part 3 is made of YT15 cemented carbide with a hardness of 91HRA.

[0049] The main symbols, meanings, values, and units used in the calculations are shown in the table below:

[0050]

[0051] The minimum interference required to transfer the load can be calculated using the formula in Table 1, and the results are as follows:

[0052] Table 1

[0053]

[0054]

[0055] The maximum effective interference fit that allows the coupling to not undergo plastic deformation can be calculated using the formulas in Table 2:

[0056] Table 2

[0057]

[0058] Note: The selection of conical interference fits shall be in accordance with GB / T 15755-1995, "Calculation and Selection of Conical Interference Fits".

[0059] As can be seen from the above calculations, the interference fit between the assembly and the first receiving cavity should satisfy: [δmin]>δ min , [δmax]<δ emax .

[0060] In actual manufacturing, the product requires the distance M between the two pins of the workpiece to meet a tolerance of 0.01 / 0. Based on the above calculations, the enclosed part 3... Theoretical calculations can meet practical requirements.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A design method for a cold extrusion die with adjustable spline parameters, characterized in that, Cold extrusion dies include: An enclosure having a through first receiving cavity; An intermediate sleeve, which is press-fitted into the first receiving cavity, the intermediate sleeve including an outer conical surface that contacts the inner wall of the first receiving cavity and a through second receiving cavity; The enclosed part is press-fitted into the second receiving cavity, which has a through toothed extrusion cavity, the inner wall of which has teeth for forming external splines; The design method includes the following steps: S1. Press the enclosed member into the second receiving cavity, and the enclosed member and the intermediate sleeve form an assembly; S2. Press the assembly into the first receiving cavity, and adjust the bar spacing of the teeth by adjusting the length of the assembly pressed into the first receiving cavity, or by changing the tolerance fit interference between the first receiving cavity and the assembly.

2. The design method according to claim 1, characterized in that, In step S2, the range of values ​​for the tolerance fit interference is obtained through the following steps: The minimum interference required to transfer the load can be calculated using the formula in Table 1: Table 1 The maximum effective interference fit that allows for no plastic deformation in a conical interference fit can be calculated using the formulas in Table 2: Table 2 3. The design method according to claim 2, characterized in that, Average cone diameter d at the mating surface m Obtained through equation (1): Where: d f2 C is the maximum cone diameter of the mating surface, and C is the taper of the mating surface.

4. The design method according to claim 1, characterized in that, It also includes step S3: S3. Assemble the pad block in the first receiving cavity. The pad block is located below the assembly and has a through hole that is connected to the toothed extrusion cavity.

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