A method and die for achieving heading forming of a fastener head structure

Abstract

The application provides a method and a die for realizing heading forming of a fastener head structure, and comprises the following steps: adopting the die to perform one-time heading on the fastener head structure to obtain a rough heading head type; and adopting the die to perform two-time heading on the rough heading head type to obtain a fine heading head type.The application has the beneficial effects that: the product size consistency is good; the new forming method is adopted, the product head type is replaced by heading instead of turning, the influences of unstable clamping, tool wear and unstable personnel operation during turning are avoided, the product processing process is stable, and the size consistency is good; the material utilization rate is high; the product head type is replaced by heading instead of turning, the head type size is directly formed by heading, the original turning head type condition is avoided, and the material utilization rate is improved from less than 80% to 100%.

Description

Technical Field

[0001] This invention belongs to the field of fastener head upsetting technology, and in particular relates to a method and mold for upsetting fastener head structures. Background Technology

[0002] The trend towards high precision, high reliability, and long lifespan in modern aircraft and other aerospace vehicles places increasingly higher demands on the structure, materials, and dimensional accuracy of fasteners. This poses higher requirements for the manufacturing of fastener products. Product structures are becoming increasingly refined, and high-strength alloys such as titanium alloys and high-temperature alloys are being used. These materials have high resistance to deformation, and the high dimensional accuracy further complicates the upsetting process.

[0003] like Figure 1 The diagram shows the head structure of a certain type of fastener product. It is a cylindrical head structure with a dovetail-shaped support surface. The product material is GH2132 high-temperature alloy. The main dimensions include transition arcs A, B, and C, the outer circle of the head D, the head height H, and the inclination angle α of the support surface. To meet installation and usage requirements, the tolerance of the outer circle D is generally 0.05–0.08 mm, the tolerance of the head height H is generally 0.10–0.15 mm, the tolerance of the inclination angle α of the support surface is generally 5°, the tolerance of the transition arc B is generally 0.1–0.2, and the tolerances of the transition arcs A ≈ 0.2 and C ≈ 0.5.

[0004] Due to the strict dimensional control requirements and high material deformation resistance of this type of product, direct upsetting is quite difficult. Currently, this type of product is generally processed by using a cold upsetting machine to rough upset the head, followed by lathe turning. Figure 2 As shown. However, this method has low processing efficiency, low material utilization, and high production costs. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method and mold for upsetting fastener head structures to solve at least one of the problems existing in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for upsetting a fastener head structure includes the following steps:

[0008] S1. The fastener head structure is upsetting once using a die to obtain a rough upsetting head shape;

[0009] S2. The rough upsetting head is forged a second time using a mold to obtain the fine upsetting head.

[0010] Furthermore, in step S1, the first upsetting forging adopts a semi-closed or closed upsetting method to cause upsetting deformation of the fastener head structure, thereby obtaining a rough upsetting head shape.

[0011] Furthermore, in step S2, the secondary upsetting forging adopts a closed extrusion method to precisely form the head shape, thereby obtaining a precision upsetting head shape.

[0012] Furthermore, in step S1, the dimensions of the rough upsetting head after one upsetting include transition arc A2, transition arc B2, transition arc C2, head outer circle D2, head height H2, support surface inclination angle α2, and head cone angle β;

[0013] In step S2, the dimensions of the rough upsetting head after the secondary upsetting include transition arc A, transition arc B, transition arc C, head outer circle D, head height H, support surface inclination angle α, and head cone angle β.

[0014] Furthermore, the outer circle D2 of the head is smaller than the outer circle D of the head, the cone angle β of the head is in the range of 15° to 25°, the relationship between the support surface inclination angle α2 and the support surface inclination angle α is: α2≥α, the relationship between the transition arc A2 and the transition arc A is: A2≈A, and the transition arc B2 is larger than the transition arc B.

[0015] A mold for upsetting a fastener head structure includes a primary upsetting mold and a secondary upsetting mold. The primary upsetting mold is used in step S1 to perform a primary upsetting of the fastener head structure to obtain a rough upsetting head shape. The secondary upsetting mold is used in step S2 to perform a secondary upsetting of the rough upsetting head shape to obtain a fine upsetting head shape.

[0016] Furthermore, the primary upsetting forming die includes an A-die, a primary main die, and a primary main die ejector pin. The primary main die is installed on one side of the A-die, and a receiving cavity for accommodating the primary workpiece die is opened on the side of the A-die near the primary main die. A forming channel is opened in the middle of the primary main die, and a main die ejector pin is installed on the right side of the forming channel. The primary main die is used to accommodate the primary workpiece on the left side of the forming channel.

[0017] Furthermore, the primary upsetting forming die includes a primary die ejector pin, a B die, a primary main die, and a primary main die ejector pin. The primary main die is installed on one side of the B die. The B die has a channel for installing the primary die ejector pin on the side away from the primary main die. The B die has a receiving cavity for accommodating the primary workpiece die on the side closer to the primary main die. A forming channel is formed in the middle of the primary main die. The main die ejector pin is installed on the right side of the forming channel. The main die is used to accommodate the primary workpiece on the left side of the forming channel.

[0018] Furthermore, the secondary upsetting forming die includes a secondary punch, a secondary main die, and a secondary main die ejector pin. A secondary forming channel is provided in the middle of the secondary main die, and the secondary punch, the secondary workpiece, and the secondary main die ejector pin are installed sequentially from left to right in the secondary forming channel.

[0019] Furthermore, the secondary main mold includes a mold core A, a mold core B, a mold sleeve, and a pad. The mold core A, the mold core B, and the pad are sequentially fitted inside the mold sleeve from left to right. One end of the secondary punch and the punch of the secondary workpiece are sequentially fitted inside the mold core A from left to right. The main mold of the secondary workpiece and one end of the secondary main mold ejector rod are sequentially fitted inside the mold core B from left to right. The other end of the secondary main mold ejector rod passes through the pad and is located outside the mold sleeve.

[0020] Furthermore, the A mold core, B mold core, and pad block are assembled with the mold sleeve by an interference fit.

[0021] Furthermore, the A mold core has several venting grooves equidistantly spaced on it, and the A mold core is provided with a guide structure with an angle γ and a length L.

[0022] Compared with existing technologies, the method and mold for upsetting fastener head structures described in this invention have the following advantages:

[0023] (1) The method and mold for upsetting the head structure of fasteners described in this invention have good product size consistency: the new forming method replaces turning with upsetting, avoiding the influence of factors such as unstable clamping, tool wear and unstable operation of personnel during turning. The product processing is stable and the size consistency is good. The material utilization rate is high: the head shape is upset instead of turning, and the head shape size is directly upset, avoiding the situation of turning the head shape in the original solution. The material utilization rate is increased from less than 80% to 100%.

[0024] (2) The method and mold for upsetting the head structure of fasteners described in this invention have high production efficiency: the original solution uses turning to form the head shape, with an average daily production capacity of 2,000 pieces, while the new solution uses upsetting to form, with an average daily production capacity of more than 16,000 pieces, and the production efficiency is more than 8 times that of the original solution; the production cost is low: the new solution saves the turning process, and can save more than 2,000 yuan in production costs for every 10,000 products. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a schematic diagram of the head structure of a certain type of fastener as described in the prior art of this invention;

[0027] Figure 2 This is a schematic diagram of the conventional processing and forming method described in the prior art of this invention (the left side is the rough upsetting head type, and the right side is the fine upsetting head type);

[0028] Figure 3 This is a schematic diagram of the forming method described in an embodiment of the present invention (the left side is the rough upsetting head type, and the right side is the fine upsetting head type);

[0029] Figure 4 This is a schematic diagram of the one-time upsetting forming die structure (Type I) according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the one-time upsetting forming die structure (Type II) according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the secondary upsetting forming die structure according to an embodiment of the present invention;

[0032] Figure 7 This is a cross-sectional view of the A mold core according to an embodiment of the present invention;

[0033] Figure 8 for Figure 7 A magnified view of a portion of the image;

[0034] Figure 9 This is a schematic diagram of the exhaust channel structure according to an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. A-die; 2. Primary workpiece; 3. Primary main die; 4. Primary main die ejector pin; 5. Primary die ejector pin; 6. B-die; 7. Secondary die; 8. Secondary main die; 9. Secondary workpiece; 10. Secondary main die ejector pin; 11. A-die core; 12. B-die core; 13. Die sleeve; 14. Spacer block. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] like Figures 1 to 9 As shown, a method and mold for upsetting the head structure of a fastener are disclosed. The head shape is formed by two upsetting processes. The first upsetting uses a semi-closed (or closed) upsetting method to deform the raw material, obtaining a rough upset head shape with a conical truncated platform and specified dimensions. The second upsetting uses a closed extrusion method to precisely form the head shape, obtaining a fine upset head shape that meets the product's head shape dimensional requirements. Figure 3 As shown.

[0042] In this forming method, the head shape dimensions after one upsetting mainly include transition arcs A2, B2, and C2, head outer circle D2, head height H2, support surface inclination angle α2, and head cone angle β. Its shape is mainly composed of a semi-closed (or closed) cavity formed by the die and the main die (see...). Figure 4 , Figure 5 To ensure smooth secondary upsetting and improve product forming stability and die life, it is necessary to reasonably control the rough forming dimensions, i.e., to rationally design the initial punch die dimensions. This is now being addressed... Figure 3 The dimensions are explained as follows:

[0043] (1) D2: The D2 dimension is mainly guaranteed by the die during the first upsetting. In order to reduce the forming force during the second upsetting, the D2 dimension should be as large as possible. At the same time, considering that the blank formed by rough upsetting can be smoothly inserted into the die during the second upsetting, the D2 dimension should be smaller than the D dimension. For example, when D≤10mm, it is recommended that D2=D-(0.1~0.3).

[0044] (2) β: The β dimension is guaranteed by the die during the first upsetting, that is, the draft angle of the die cavity, which is generally 15° to 25°.

[0045] (3) H2: The size of H2 is mainly guaranteed by the die during the first upsetting. Generally, after the dimensions of D2 and β are determined, H2 is calculated according to the principle of equal volume.

[0046] (4) α2: The dimension of α2 is guaranteed by the main die during the first upsetting. Generally, α2 ≥ α, and the value is determined according to the deformation characteristics.

[0047] (5) A2: The A2 dimension is freely formed during one upsetting. The greater the upsetting force during one upsetting, the smaller the A2 dimension. It is recommended that A2≈A.

[0048] (6) B2: The B2 dimension is guaranteed by the main die during the first upsetting. In order to reduce the forming force during the second upsetting and to avoid defects such as folding at the joint of the head and rod during the forming process, the B2 dimension should be slightly larger than the B dimension. For example, when B≤1mm, it is recommended that B2=B+(0.05~0.15).

[0049] (7)C2: The C2 dimension is guaranteed by the die during the first upsetting. The design of this dimension is mainly determined by the relationship between D2 and D and D, H2 and H and the deformation characteristics of the product material.

[0050] The structure of the die for one-time upsetting is as follows Figure 4 As shown, it mainly consists of A-die 1, primary main die 3, and primary main die ejector pin 4. The primary workpiece 2 undergoes upsetting deformation within the cavity it forms, obtaining... Figure 3 The rough upsetting profile is shown. It should be noted that the die used for primary upsetting can also be as shown... Figure 5 The structure shown mainly consists of a primary die ejector pin 5, a B die 6, a primary main die 3, and a primary main die ejector pin 4. The workpiece 2 undergoes upsetting deformation within the cavity formed by these components to obtain... Figure 3 The rough upsetting shape structure is shown.

[0051] The structure of the die for secondary upsetting is as follows Figure 6 As shown, it mainly consists of a secondary die 7, a secondary main die 8, and a secondary main die ejector pin 10. During the forming process, the secondary die 7 penetrates into the secondary main die 8, and the secondary workpiece 9 undergoes extrusion deformation within the cavity formed by the secondary die 7, the secondary main die 8, and the secondary main die ejector pin 10 to obtain... Figure 3 The outline structure of the precision upsetting is shown.

[0052] like Figure 7 As shown, the secondary main die 8 for secondary upsetting consists of four parts: die core A 11, die core B 12, die sleeve 13, and spacer block 14. Die core A 11, die core B 12, and spacer block 14 are assembled with die sleeve 13 by interference fit. Die core A 11 and die core B 12 are made of high-strength, wear-resistant materials, die sleeve 13 is made of a material with high strength and toughness, and spacer block 14 is made of a high-strength material. Die core A 11 and die core B 12 are in direct contact with the workpiece and are the core parts for forming the workpiece. Spacer block 14 is used to bear the axial pressure of die core A 11 and die core B 12 and transmit it to the upsetting equipment. Die sleeve 13 combines die core A 11, die core B 12, and spacer block 14 together and applies a certain prestress to die core A 11 and die core B 12 to improve the service life of die core A 11 and die core B 12. During the forming process, mold core A 11 is mainly subjected to radial tensile stress, mold core B 12 is mainly subjected to axial compressive stress, and the outer diameter of the head of the secondary workpiece 9 ( Figure 1 The middle D dimension is mainly guaranteed by the A mold core 11, and the transition arc and support surface inclination angle of the secondary workpiece 9 are also guaranteed. Figure 1 The dimensions (B and α) are mainly guaranteed by the B mold core 12.

[0053] like Figure 7 As shown, to avoid "air trapping" during the extrusion process, which would result in incomplete forming of the workpiece head, a number of venting groove structures are designed on the A mold core 11. To avoid rigid impact between molds and to facilitate the smooth insertion of the secondary punch 7 into the secondary main mold 8, a guide structure with a γ tilt angle and L length is designed on the A mold core 11.

[0054] It should be further noted that the final external dimensions of the product ( Figure 1 The parameters B, D, α, and H are directly guaranteed by the secondary main mold 8. In the mold design, B3≈B, D3≈D, and α3≈α. In addition, H3≥H ensures that there is enough space in the mold head to form the product head. However, if H3 is too large, it will cause excessive friction during demolding, which can easily cause damage to the cylindrical surface of the product head.

[0055] The secondary main die 8 for secondary upsetting adopts a combined structure (composed of die core A and die core B). On the one hand, it facilitates die processing and manufacturing and the processing of venting grooves. On the other hand, it can effectively release stress and avoid die core cracking due to different stress states (tensile stress in die core A and compressive stress in die core B), thus reducing the service life of the die.

[0056] Compared with conventional forming methods, the novel forming method proposed in this invention has significant advantages in upset forming of head shapes:

[0057] (1) Good product dimensional consistency. The new forming method is adopted, and the product head shape is "upsetting instead of turning", which avoids the influence of factors such as unstable clamping, tool wear and unstable operation of personnel during turning. The product processing is stable and the dimensional consistency is good.

[0058] (2) High material utilization rate. The product head shape is "upset instead of turned", and the head shape size is directly upset, avoiding the original solution of turning the head shape. The material utilization rate has increased from less than 80% to 100%.

[0059] (3) High production efficiency. The original design used turning to form the head shape, with an average daily production capacity of 2,000 pieces. The new design uses upsetting to form the head shape, with an average daily production capacity of more than 16,000 pieces. The production efficiency is more than 8 times that of the original design.

[0060] (4) Low production cost. The new solution saves the turning process, and can save more than 2,000 yuan in production costs for every 10,000 products.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for upsetting a fastener head structure, characterized in that: Includes the following steps: S1. The fastener head structure is upsetting once using a die to obtain a rough upsetting head shape; S2. The rough upsetting head is forged a second time using a die to obtain the fine upsetting head. In step S1, the first upsetting forging uses a semi-closed or closed upsetting method to cause upsetting deformation of the fastener head structure, thereby obtaining a rough upsetting head shape; In step S2, the secondary upsetting forging uses a closed extrusion method to precisely form the head shape, thereby obtaining a precision upsetting head shape; In step S1, the dimensions of the rough upsetting head after one upsetting include transition arc A2, transition arc B2, transition arc C2, head outer circle D2, head height H2, support surface inclination angle α2, and head cone angle β; In step S2, the dimensions of the rough upsetting head after the second upsetting include transition arc A, transition arc B, transition arc C, head outer circle D, head height H, support surface inclination angle α, and head cone angle β; The outer circle D2 of the head is smaller than the outer circle D of the head, the cone angle β of the head is in the range of 15°~25°, the relationship between the support surface inclination angle α2 and the support surface inclination angle α is: α2≥α, the relationship between the transition arc A2 and the transition arc A is: A2≈A, and the transition arc B2 is larger than the transition arc B. A mold for upsetting a fastener head structure is provided, which is applied to the method for upsetting a fastener head structure. The mold includes a primary upsetting mold and a secondary upsetting mold. The primary upsetting mold is used to perform a primary upsetting of the fastener head structure in step S1 to obtain a rough upsetting head shape. The secondary upsetting mold is used to perform a secondary upsetting of the rough upsetting head shape in step S2 to obtain a fine upsetting head shape. The secondary upsetting forming die includes a secondary punch (7), a secondary main die (8) and a secondary main die ejector (10). The secondary main die (8) has a secondary forming channel in the middle. The secondary forming channel is installed with the secondary punch (7), the secondary workpiece (9) and the secondary main die ejector (10) from left to right. The secondary main mold (8) includes an A mold core (11), a B mold core (12), a mold sleeve (13), and a pad (14). The A mold core (11), the B mold core (12), and the pad (14) are sequentially fitted inside the mold sleeve (13) from left to right. One end of the secondary punch (7) and the punch of the secondary workpiece (9) are sequentially fitted inside the A mold core (11) from left to right. One end of the main mold of the secondary workpiece (9) and the secondary main mold ejector (10) are sequentially fitted with the B mold core (12) from left to right. The other end of the secondary main mold ejector (10) passes through the pad (14) and is located outside the mold sleeve (13). The A mold core (11), B mold core (12) and pad (14) are assembled with the mold sleeve (13) by an interference fit. The A mold core (11) has several venting grooves equidistantly spaced on it, and the A mold core (11) is provided with a guide structure with an inclination angle of γ and a length of L.

2. The method for upsetting a fastener head structure according to claim 1, characterized in that: The primary upsetting forming die includes an A-die (1), a primary main die (3), and a primary main die ejector pin (4). The primary main die (3) is installed on one side of the A-die (1). The A-die (1) has a receiving cavity for accommodating the primary workpiece (2) on the side near the primary main die (3). A forming channel is provided in the middle of the primary main die (3). The main die ejector pin is installed on the right side of the forming channel. The main die is used to accommodate the primary workpiece (2) on the left side of the forming channel.

3. The method for upsetting a fastener head structure according to claim 1, characterized in that: The primary upsetting forming die includes a primary die ejector pin (5), a B die (6), a primary main die (3), and a primary main die ejector pin (4). The primary main die (3) is installed on one side of the B die (6). The B die (6) has a channel for installing the primary die ejector pin (5) on the side away from the primary main die (3). The B die (6) has a receiving cavity for accommodating the primary workpiece (2) on the side close to the primary main die (3). A forming channel is provided in the middle of the primary main die (3). The main die ejector pin is installed on the right side of the forming channel. The main die is used to accommodate the primary workpiece (2) on the left side of the forming channel.

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