Spinning drawing machining tool and method for seamless tube with variable wall thickness

Abstract

The invention relates to the technical field of metal pipe machining, and discloses a spinning and drawing machining tool and method for a variable-wall-thickness seamless pipe, the machining tool comprises a male die, a female die, a lifting gasket and balls, and the female die is provided with a truncated conical surface. The working molded surface of the female die is changed into a truncated cone structure from a traditional cylindrical shape, and the lifting gasket can move upwards or downwards in the spinning and drawing process, so that the contact position of the ball and the female die moves upwards or downwards, and the purpose of variable-wall-thickness machining is achieved; the variable wall thickness machining requirement that the wall thickness of the cylindrical blank piece is in linear, stepped or nonlinear progressive increase change from the thin end to the thick end in the length direction can be met; besides, in the axial moving process of the cylindrical blank piece, the height of the lifting gasket is adjusted in real time according to the design thickness value of each axial position of the variable-wall-thickness seamless pipe, so that the thickness size of each axial position of the variable-wall-thickness seamless pipe machined and formed by the cylindrical blank piece meets the requirement of the design thickness value.

Description

Technical Field

[0001] The invention relates to the technical field of metal pipe processing, and discloses a spinning and drawing processing tool and method for a seamless pipe with variable wall thickness. Background Art

[0002] Seamless pipes with constant inner diameter and variable wall thickness can be used in the manufacture of pipeline systems and similar parts of aerospace vehicles. They have the advantages of light weight, high processing efficiency and good mechanical properties. Typical applications include Figure 1 The aircraft pitot tube shell parts shown in the figure are installed at the front end of the aircraft fuselage to sense the total static pressure of the atmosphere. They are hollow cantilever structures. The shell under the equal strength design should be a tube body with a gradual wall thickness, which is beneficial to reduce weight and improve vibration resistance compared with the equal wall thickness structure.

[0003] Spinning is a metal plastic processing technology with little or no chipping that combines the process characteristics of forging, extrusion, drawing, bending, ring rolling, cross rolling and rolling. During spinning, the spinning wheel squeezes the material from one side of the blank onto the rotating mandrel, causing the material to undergo point-by-point continuous plastic deformation, thereby obtaining hollow rotating body parts of various generatrix shapes. Spinning and drawing is a branch of strong thinning spinning, also known as ball spinning; such as Figure 2 As shown, a plurality of balls 5 are used instead of a spinning wheel, and the cylindrical blank 7 is thinned and formed under the joint action of the balls 5, the spinning rod 1 and the female mold 2. This process has been widely used in the production of thin-walled seamless pipes. In addition to the general characteristics of the spinning method, ball spinning also has the following advantages:

[0004] The surface roughness of the pipe fittings is low and the dimensional accuracy is high: Since the ball used as the deformation tool has low surface roughness and high dimensional accuracy, the deformation mode of the deformation zone is point-by-point deformation, and the elastic deformation is very small, it ensures that the outer diameter of the pipe fittings after spinning can be controlled within ±0.005mm, the surface roughness can usually reach 0.2μm, and the thinnest pipe wall can reach 0.04mm.

[0005] The mechanical properties of the pipe fittings are improved: the metal pipe fittings are in a three-dimensional compressive stress state in the deformation zone. After deformation, the material grains are elongated and the structure is refined. It has a continuous fiber structure, which improves the yield strength and hardness of the metal.

[0006] High deformation efficiency: For metals and alloys with good plasticity, the cross-sectional shrinkage rate of ball spinning can reach 70-85%, and the deformation amount is large. Compared with drawing and cutting processes, it can significantly improve production efficiency.

[0007] It has the effect of material self-inspection: During the spinning process, the tube blank is squeezed and deformed point by point by the ball. The hidden defects such as inclusions, interlayers, cracks, etc. in the tube blank are easily exposed during the large deformation process, which plays a role in self-inspection of the tube blank material.

[0008] Due to the limitations of process principles and mold structure, the above method can only process conventional cylindrical seamless pipes with equal wall thickness, but cannot meet the manufacturing needs of variable wall thickness pipes. Summary of the invention

[0009] The purpose of the present invention is to provide a spinning and drawing processing tool and method for variable wall thickness seamless pipes, which can meet the variable wall thickness processing needs of tubular blanks with wall thickness changing linearly, step-wise or nonlinearly from the thin end to the thick end along the length direction, and can ensure that the thickness dimensions of the processed variable wall thickness seamless pipes at each axial position meet the design thickness value requirements by adjusting the height position of the lifting gasket during the spinning and drawing process.

[0010] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0011] A spinning and drawing tool for a variable wall thickness seamless pipe, comprising:

[0012] A male mold, the male mold comprising a spinning rod that can be fixed to the inner cavity of the cylindrical blank;

[0013] A female mold, wherein the female mold is provided with a forming groove for allowing the cylindrical blank to pass through the female mold, and the working surface of the forming groove is a truncated cone surface, the large-diameter end of the truncated cone surface is located on the upper surface of the female mold, and the small-diameter end of the truncated cone surface extends through the lower surface of the female mold;

[0014] A lifting washer, the lifting washer is coaxially placed in the molding groove of the female mold;

[0015] Balls, there are multiple balls, and the multiple balls are circumferentially distributed in the annular gap between the outer wall of the cylindrical blank and the truncated cone surface; the outer wall of the ball is in contact with the truncated cone surface and the outer wall of the cylindrical blank, and the bottom surface of the ball is in contact with the upper end surface of the lifting washer.

[0016] Furthermore, the diameter of the ball is smaller than the width of the annular gap between the cylindrical blank and the large diameter end of the female die truncated cone surface, and the diameter of the ball is greater than or equal to the width of the annular gap between the minimum outer diameter position of the variable wall thickness seamless pipe product and the small diameter end of the female die truncated cone surface.

[0017] Furthermore, the small-diameter end of the truncated cone surface extends to the interior of the female mold, and the female mold is provided with a cylindrical groove for accommodating the lifting washer at a position corresponding to the lifting washer.

[0018] Furthermore, the spinning rod is a cylindrical structure having an inner diameter equal to that of the cylindrical blank.

[0019] In order to achieve the above technical effects, the present invention also provides a spinning and drawing method for a variable wall thickness seamless pipe, which is based on the spinning and drawing tooling for the variable wall thickness seamless pipe, and comprises:

[0020] The male mold is fixed on the driving mechanism, so that the spinning rod of the male mold is coaxially arranged with the truncated cone surface of the female mold, and the spinning rod is located directly above the truncated cone surface of the female mold; the driving mechanism is used to drive the spinning rod of the male mold to rotate along the axial direction of the spinning rod, and move the spinning rod toward the truncated cone surface of the female mold;

[0021] The cylindrical blank to be processed is coaxially sleeved on the spinning rod, and the spinning rod is fixed to the cylindrical blank, and the cylindrical blank is used for processing to obtain a variable wall thickness seamless pipe;

[0022] The driving mechanism is started to make the spinning rod drive the cylindrical blank to rotate and pass through the truncated cone surface; wherein, during the axial movement of the cylindrical blank, the height of the lifting gasket is adjusted in real time according to the design thickness value of each axial position of the variable wall thickness seamless pipe, so that the thickness size of each axial position of the variable wall thickness seamless pipe formed by the cylindrical blank meets the design thickness value requirement.

[0023] Furthermore, one or more spinning and drawing forming methods are adopted in the spinning and drawing process, so that the thickness dimensions of the variable wall thickness seamless pipe formed by the cylindrical blank at each axial position meet the design thickness value requirements.

[0024] Furthermore, during each spinning and drawing process, the height of the lifting washer is adjusted so that the height h of the ball center point relative to the small diameter end face of the truncated cone surface is i Satisfy h i =r0sinα+(r+d i +r0+r0cosα-R0)·cotα, so that the thickness of the cylindrical blank at each axial position meets the thickness control value requirement of the current spinning and drawing process; repeat the spinning and drawing for many times until the thickness of the variable wall thickness seamless pipe at each axial position meets the design thickness value requirement; wherein r0 is the radius of the ball, α is the inclination angle of the truncated cone surface, r is the inner diameter of the cylindrical blank, and R0 is the inner diameter of the small diameter end of the truncated cone surface; d i It is the thickness control value of the i-th axial position of the cylindrical blank during one spinning and drawing process, or the design thickness value of the i-th axial position on the finished variable wall thickness seamless tube.

[0025] Furthermore, the diameter of the ball is smaller than the width of the annular gap between the cylindrical blank and the large diameter end of the female die truncated cone surface, and the diameter of the ball is greater than or equal to the width of the annular gap between the minimum outer diameter position of the finished product of the cylindrical blank and the small diameter end of the female die truncated cone surface.

[0026] Furthermore, the spinning rod is a cylindrical structure having an inner diameter equal to that of the cylindrical blank.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. By changing the working surface of the female die from the traditional cylindrical shape to a truncated cone structure, the lifting washer can move upward or downward during the spinning and drawing process, so that the contact position between the ball and the female die moves up or down, thereby achieving the purpose of variable wall thickness processing, which can meet the variable wall thickness processing requirements of the cylindrical blank whose wall thickness changes linearly, step-shaped or nonlinearly from the thin end to the thick end along the length direction.

[0029] 2. The present invention can also adjust the height of the lifting gasket in real time according to the design thickness value of each axial position of the variable wall thickness seamless pipe, so that the thickness size of each axial position of the variable wall thickness seamless pipe formed by the cylindrical blank meets the design thickness value requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a typical aircraft pitot tube structure;

[0031] Figure 2 It is a schematic diagram of the existing tooling structure for processing cylindrical seamless pipes with equal wall thickness for spinning and drawing;

[0032] Figure 3 It is a schematic diagram of the structure of the spinning and drawing tooling for the variable wall thickness seamless pipe in the embodiment;

[0033] Figure 4 It is a flow chart of the spinning and drawing method of the variable wall thickness seamless pipe in the embodiment;

[0034] Among them, 1. spinning rod; 2. female mold; 3. truncated cone surface; 4. lifting washer; 5. ball; 6. cylindrical groove; 7. tubular blank; 8. variable wall thickness seamless pipe. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0036] Example

[0037] See also Figure 3 and Figure 4 , a spinning and drawing tool for a variable wall thickness seamless pipe, comprising:

[0038] A male mold, the male mold comprising a spinning rod 1 that can be fixed to the inner cavity of a cylindrical blank 7;

[0039] A female mold 2 is provided with a forming groove for allowing a cylindrical blank 7 to pass through the female mold 2, and the working surface of the forming groove is a truncated cone surface 3, the large-diameter end of the truncated cone surface 3 is located on the upper surface of the female mold 2, and the small-diameter end of the truncated cone surface 3 extends to the inside of the female mold 2 or penetrates to the lower surface of the female mold 2;

[0040] A lifting washer 4, the lifting washer 4 is coaxially placed in the molding groove of the female mold 2;

[0041] Ball 5, there are multiple balls 5, and the multiple balls 5 are circumferentially distributed in the annular gap between the outer wall of the cylindrical blank 7 and the truncated cone surface 3; the outer wall of the ball 5 is in contact with the truncated cone surface 3 and the outer wall of the cylindrical blank 7, and the bottom surface of the ball 5 is in contact with the upper end surface of the lifting washer 4.

[0042] In this embodiment, before the cylindrical blank 7 is spun and drawn into the variable wall thickness seamless tube 8, the inner surface of the tube of the cylindrical blank structure is first fitted and coaxially fixed with the spinning rod 1 of the male mold. Since the working surface of the female mold 2 is changed from a cylindrical shape to a truncated cone surface 3 structure, the lifting washer 4 can move upward or downward during the spinning and drawing process, so that the contact position of the ball 5 and the female mold 2 moves up or down, thereby achieving the purpose of variable wall thickness processing, which can meet the variable wall thickness processing requirements of the cylindrical blank 7 whose wall thickness changes linearly, step-like or nonlinearly along the length direction from the thin end to the thick end.

[0043] Based on the same inventive concept, this embodiment also provides a spinning and drawing method for a variable wall thickness seamless pipe, which is based on the spinning and drawing tooling for the variable wall thickness seamless pipe, and includes:

[0044] Step 1, fix the male mold on the driving mechanism, so that the spinning rod 1 of the male mold is coaxially arranged with the truncated cone surface 3 of the female mold 2, and the spinning rod 1 is located directly above the truncated cone surface 3 of the female mold 2; the driving mechanism is used to drive the spinning rod 1 of the male mold to rotate along the axial direction of the spinning rod 1, and move the spinning rod 1 toward the truncated cone surface 3 of the female mold 2;

[0045] Step 2: Coaxially sleeve the cylindrical blank 7 to be processed on the spinning rod 1, and fix the spinning rod 1 and the cylindrical blank 7, wherein the cylindrical blank 7 is used for processing to obtain a variable wall thickness seamless pipe 8;

[0046] Step three, start the driving mechanism to make the spinning rod 1 drive the cylindrical blank 7 to rotate and pass through the truncated cone surface 3; wherein, during the axial movement of the cylindrical blank 7, the height of the lifting gasket 4 is adjusted in real time according to the design thickness value of each axial position of the variable wall thickness seamless tube 8, so that the thickness size of each axial position of the variable wall thickness seamless tube 8 formed by the cylindrical blank 7 meets the design thickness value requirement.

[0047] In this embodiment, one or more spinning and drawing forming methods are used during the spinning and drawing process, so that the thickness dimensions of the variable wall thickness seamless tube 8 formed by the cylindrical blank 7 at each axial position meet the design thickness value requirements.

[0048] In order to ensure that the finished product size of the variable wall thickness seamless pipe 8 meets the design requirements, in this embodiment, during each spinning and drawing process, the height of the lifting washer 4 is adjusted so that the height h of the center point of the ball 5 relative to the small diameter end face of the truncated cone surface 3 is i Satisfy h i =r0sinα+(r+d i +r0+r0cosα-R0)·cotα, so that the thickness of the cylindrical blank 7 at each axial position meets the thickness control value requirement of the current spinning and drawing process; repeat the spinning and drawing for many times until the thickness of the variable wall thickness seamless tube 8 at each axial position meets the design thickness value requirement; wherein r0 is the radius of the ball 5, α is the inclination angle of the truncated cone surface 3, r is the inner diameter of the cylindrical blank 7, and R0 is the inner diameter of the small diameter end of the truncated cone surface 3; d i It is the thickness control value of the tubular blank 7 at the i-th axial position during one spinning and drawing process, or the design thickness value of the i-th axial position on the finished variable wall thickness seamless tube 8.

[0049] To ensure that the ball 5 can maintain interaction with the outer wall of the pipe during the spinning and drawing process, the diameter of the ball 5 in this embodiment is smaller than the width of the annular gap between the cylindrical blank 7 and the large-diameter end of the truncated cone surface 3 of the female die 2, and the diameter of the ball 5 is greater than or equal to the width of the annular gap between the minimum outer diameter position of the finished variable-wall thickness seamless pipe 8 and the small-diameter end of the truncated cone surface 3 of the female die 2.

[0050] The spinning rod 1 in this embodiment is a cylindrical structure with an inner diameter equal to that of the cylindrical blank 7, ensuring that the inner diameter of the cylindrical blank 7 will not change during the spinning and drawing process, thereby ensuring the accuracy and roughness of the inner diameter.

[0051] In this embodiment, the small-diameter end of the truncated cone surface 3 extends to the interior of the female mold 2, and the female mold 2 is provided with a cylindrical groove 6 for accommodating the lifting gasket 4 at the position corresponding to the lifting gasket 4. The cylindrical groove 6 can cooperate with the lifting gasket 4 to guide the lifting gasket 4, ensuring that the lifting process of the lifting gasket 4 maintains axial movement along the cylindrical blank 7, further ensuring the accuracy of the thickness dimensions of each axial position of the processed variable-wall thickness seamless pipe 8.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A spinning and drawing tool for a variable wall thickness seamless pipe, characterized in that: include: A male mold, the male mold comprising a spinning rod that can be fixed to the inner cavity of the cylindrical blank; A female mold, wherein the female mold is provided with a forming groove for allowing the cylindrical blank to pass through the female mold, and the working surface of the forming groove is a truncated cone surface, the large-diameter end of the truncated cone surface is located on the upper surface of the female mold, and the small-diameter end of the truncated cone surface extends through the lower surface of the female mold; A lifting washer, the lifting washer is coaxially placed in the molding groove of the female mold; Balls, there are multiple balls, and the multiple balls are circumferentially distributed in the annular gap between the outer wall of the cylindrical blank and the truncated cone surface; the outer wall of the ball is in contact with the truncated cone surface and the outer wall of the cylindrical blank, and the bottom surface of the ball is in contact with the upper end surface of the lifting washer.

2. The spinning and drawing tool for variable wall thickness seamless pipe according to claim 1, characterized in that: The diameter of the ball is smaller than the annular gap width between the cylindrical blank and the large diameter end of the female die truncated cone surface, and the diameter of the ball is greater than or equal to the annular gap width between the minimum outer diameter position of the variable wall thickness seamless pipe product and the small diameter end of the female die truncated cone surface.

3. The spinning and drawing tool for variable wall thickness seamless pipe according to claim 1, characterized in that: The small-diameter end of the truncated cone surface extends to the interior of the female mold, and the female mold is provided with a cylindrical groove for accommodating the lifting washer at a position corresponding to the lifting washer.

4. The spinning and drawing tool for variable wall thickness seamless pipe according to claim 1, characterized in that: The spinning rod is a cylindrical structure having an inner diameter equal to that of the cylindrical blank.

5. A spinning and drawing method for a variable wall thickness seamless pipe, the method is based on the spinning and drawing tool for a variable wall thickness seamless pipe according to claim 1, characterized in that: include: The male mold is fixed on the driving mechanism, so that the spinning rod of the male mold is coaxially arranged with the truncated cone surface of the female mold, and the spinning rod is located directly above the truncated cone surface of the female mold; the driving mechanism is used to drive the spinning rod of the male mold to rotate along the axial direction of the spinning rod, and move the spinning rod toward the truncated cone surface of the female mold; The cylindrical blank to be processed is coaxially sleeved on the spinning rod, and the spinning rod is fixed to the cylindrical blank, and the cylindrical blank is used for processing to obtain a variable wall thickness seamless pipe; The driving mechanism is started to make the spinning rod drive the cylindrical blank to rotate and pass through the truncated cone surface; wherein, during the axial movement of the cylindrical blank, the height of the lifting gasket is adjusted in real time according to the design thickness value of each axial position of the variable wall thickness seamless pipe, so that the thickness size of each axial position of the variable wall thickness seamless pipe formed by the cylindrical blank meets the design thickness value requirement.

6. The spinning and drawing method of a variable wall thickness seamless pipe according to claim 5, characterized in that: During the spinning and drawing process, one or more spinning and drawing forming methods are adopted to ensure that the thickness dimensions of the variable wall thickness seamless pipe formed from the cylindrical blank at each axial position meet the design thickness value requirements.

7. The spinning and drawing method of a variable wall thickness seamless pipe according to claim 6, characterized in that: During each spinning and drawing process, adjust the height of the lifting washer so that the height h of the ball center point relative to the small diameter end face of the truncated cone surface is i Satisfy h i =r0sinα+(r+d i +r0+r0cosα-R0)·cotα, so that the thickness of the cylindrical blank at each axial position meets the thickness control value requirement of the current spinning and drawing process; repeat the spinning and drawing for many times until the thickness of the variable wall thickness seamless pipe at each axial position meets the design thickness value requirement; wherein r0 is the radius of the ball, α is the inclination angle of the truncated cone surface, r is the inner diameter of the cylindrical blank, and R0 is the inner diameter of the small diameter end of the truncated cone surface; d i It is the thickness control value of the i-th axial position of the cylindrical blank during one spinning and drawing process, or the design thickness value of the i-th axial position on the finished variable wall thickness seamless tube.

8. The spinning and drawing method of a variable wall thickness seamless pipe according to claim 5, characterized in that: The diameter of the ball is smaller than the width of the annular gap between the cylindrical blank and the large diameter end of the female die truncated cone surface, and the diameter of the ball is greater than or equal to the width of the annular gap between the minimum outer diameter position of the finished cylindrical blank and the small diameter end of the female die truncated cone surface.

9. The spinning and drawing method of a variable wall thickness seamless pipe according to claim 5, characterized in that: The spinning rod is a cylindrical structure having an inner diameter equal to that of the cylindrical blank.

Images