JP5448909B2 - Drawing machine for tubular workpieces - Google Patents

Description

  The present invention relates to a tubular workpiece drawing device, a drawing die, and a tubular workpiece drawing method.

  In the present specification and claims, the term “aluminum” is used to include both pure aluminum and aluminum alloys unless otherwise specified. Further, “upstream side” and “downstream side” mean the upstream side and the downstream side in the workpiece drawing direction, respectively.

  Conventionally, an aluminum tube having an outer surface with a surface roughness Ry of about 1.0 to 3.0 μm has been manufactured, for example, by sequentially extruding and drawing an aluminum material (eg, aluminum billet). Such a drawn tube is called an “ED (Extrusion Drawing) tube”. This drawing tube is used for a photosensitive drum substrate of an electrophotographic apparatus (copying machine, laser beam printer, etc.), for example.

  Thus, Japanese Patent Application Laid-Open No. 2005-118799 discloses a drawing apparatus (diameter reducing apparatus) provided with a drawing die for reducing the outer diameter of a metal tube as a tubular workpiece. 1). This drawing apparatus does not include a drawing plug for processing the inner surface of the pipe, that is, employs an empty drawing method, and therefore has a feature that the thickness of the pipe increases by drawing. doing. The purpose of this drawing apparatus is to suppress an increase in the thickness of the pipe without using a drawing plug, and to prevent chattering marks generated on the outer surface of the pipe during the drawing process.

  Japanese Patent Application Laid-Open No. 8-66715 discloses a method of manufacturing a solid wire or bar by drawing, not a method of manufacturing a tube (see Patent Document 2). The workpiece used in this method is solid rather than tubular. Therefore, the drawing apparatus used in this method does not need to have a drawing plug.

JP 2005-118799 A JP-A-8-66715

  Thus, the drawing tube is used for various purposes. For example, the drawing tube used for the above-described photosensitive drum substrate preferably has a mirror surface on the outer surface. Therefore, conventionally, the outer surface of the tube is made into a mirror surface by cutting the outer surface of the tube. The drawn tube whose outer surface is cut in this way is called a “cutting tube”. On the other hand, a drawn tube whose outer surface is not cut is called a “non-cut tube”.

  The cutting tube has a problem of high manufacturing cost because it is necessary to cut the outer surface of the tube. Accordingly, in order to reduce the manufacturing cost, it is desirable to use a non-cutting tube instead of a cutting tube.

  However, the non-cutting pipe has many oil pits as concave defects generated at the time of drawing on the outer surface thereof. Therefore, it has been very difficult to obtain a non-cutting tube having a highly smooth outer surface with a surface roughness Ry of, for example, 1.0 μm or less.

  Then, the present inventors earnestly studied the cause of oil pits in the drawing process, and obtained the following knowledge. This finding will be described below with reference to FIGS.

  In FIG. 4, 110 is a conventional drawing apparatus for tubular workpieces. The drawing apparatus 110 includes a drawing die 120 that processes the outer surface 40 a of the workpiece 40, and a drawing plug 130 that processes the inner surface 40 b of the workpiece 40. The shape of the extraction plug 130 is substantially ball-shaped or substantially spherical. The extraction plug 130 is provided at the distal end portion of the support bar 131 and is disposed in the hollow portion 40 c of the workpiece 40. Further, as shown in FIG. 5, on the peripheral surface of the die hole 121 of the drawing die 120, a curved surface portion 101C having an arc-shaped longitudinal section is smoothly and continuously formed at the downstream end of the die approach portion 101A. The curved surface portion 101C is smoothly formed at the upstream end F of the bearing portion 101B. The die approach portion 101A and the curved surface portion 101C are formed such that their diameters gradually decrease toward the downstream side in the drawing direction N of the workpiece 40. Further, in the cross section including the die axis X of the drawing die 120, the inclination of the tangent line of the curved surface portion 101 </ b> C with respect to the die axis X of the drawing die 120 gradually decreases as the workpiece 40 moves in the drawing direction N. The die bearing portion 101B is formed substantially parallel to the die axis X of the drawing die 120. Reference numeral 102E denotes a relief portion of the drawing die 120. 4 and 5, the workpiece 40 is indicated by dot hatching so that it can be easily distinguished from other members.

  When the tubular workpiece 40 is drawn using the drawing device 110, the workpiece 40 comes into contact with the die approach portion 101A or the curved surface portion 101C of the drawing die 120 and is reduced in diameter by the curved surface portion 101C. Guided to the die bearing portion 101B. Then, when the workpiece 40 passes between the die bearing portion 101B and the plug bearing portion 103B of the extraction plug 130, the outer surface 40a and the inner surface 40b of the workpiece 40 are simultaneously formed by the die bearing portion 101B and the plug bearing portion 103B. Finished. During the finishing process, the workpiece 40 is pressurized by the die bearing portion 101B and the plug bearing portion 103B, and the thickness of the workpiece 40 decreases. The drawing tube 41 is obtained through such material flow of the workpiece 40.

  In such a material flow of the workpiece 40, conventionally, as generally described in a drawing textbook, the workpiece 40 that is in contact with the curved surface portion 101C of the drawing die 120 remains in contact with the curved surface portion 101C. Thus, it is considered that the curved surface portion 101C is guided to the die bearing portion 101B. However, in the actual drawing process, such a material flow of the workpiece 40 does not occur. That is, as shown in FIG. 5, the workpiece 40 that contacts the curved surface portion 101C is guided from the curved surface portion 101C to the die bearing portion 101B. At this time, it was once separated from the curved surface portion 101C and re-contacted with the die bearing portion 101B. Therefore, the workpiece 40 is excessively reduced in diameter while the workpiece 40 is moving from the curved surface portion 101C to the die bearing portion 101B. As a result, the outer surface 40a of the workpiece 40 is recessed in an arc shape in the longitudinal section, and a large number of intense fine irregularities (not shown) are generated on the outer surface 40a. The lubricating oil for drawing is collected in the concave portion of the intense unevenness. In this state, the workpiece 40 passes between the die bearing portion 101B and the plug bearing portion 103B, so that the outer surface 40a and the inner surface 40b of the workpiece 40 are pressurized by the die bearing portion 101B and the plug bearing portion 103B. As a result, a large number of fine oil pits (not shown) are generated on the outer surface 41 a of the drawing tube 41. Due to such a large number of oil pits, the outer surface 41a of the drawing tube 41 becomes rough. The inventors have obtained the above findings.

  On the other hand, when the supply amount of lubricating oil is reduced to prevent the occurrence of oil pits, the outer surface 40a of the workpiece 40 is likely to be seized on the drawing die 120.

  The present invention was made based on the above technical background and the above knowledge obtained by the inventors, the purpose of which can prevent seizure with the drawing die of the outer peripheral surface of the tubular workpiece, and An object of the present invention is to provide a tubular workpiece drawing apparatus capable of processing the outer surface of the workpiece into a highly smooth surface, a drawing die suitably used in the drawing apparatus, and a tubular workpiece drawing method.

  The present invention provides the following means.

[1] A drawing die that processes the outer surface side of the tubular workpiece, and a drawing plug that is disposed in the hollow portion of the workpiece and processes the inner surface side of the workpiece,
The drawing die is
A first curved surface part that is separated while the workpiece is reduced in diameter;
A die bearing portion disposed on the inner side and downstream side of the workpiece separation position in the first curved surface portion;
A guide portion that has a second curved surface portion smoothly connected to the upstream end of the die bearing portion and guides to the die bearing portion while re-contacting the workpiece away from the first curved surface portion and reducing the diameter of the workpiece. ,
With
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The radius of curvature of the second curved surface portion is set larger than the radius of curvature of the first curved surface portion,
The drawing work apparatus for a tubular workpiece, wherein the drawing plug includes a plug bearing portion that is disposed at a position corresponding to the die bearing portion and is shorter than the length of the die bearing portion.

  [2] The drawing apparatus for tubular workpieces according to item 1 above, wherein the position of the upstream end of the plug bearing portion is the same as or downstream of the position of the upstream end of the die bearing portion.

  [3] In the cross section including the die axis of the drawing die, the inclination of the tangent line of the first curved surface portion and the inclination of the tangential line of the second curved surface portion with respect to the die axis of the drawing die are respectively in the drawing direction of the workpiece. 3. The drawing apparatus for tubular workpieces according to item 1 or 2, wherein the apparatus is gradually reduced as it progresses.

  [4] Any of the preceding items 1 to 3, wherein the guide portion has an auxiliary curved surface portion that is smoothly connected to an upstream end of the second curved surface portion and is bent in a direction opposite to a bending direction of the second curved surface portion. The drawing apparatus for tubular workpieces described in 1.

  [5] The tubular workpiece drawing apparatus according to any one of the preceding items 1 to 4, wherein a length of the plug bearing portion is set in a range of 5 to 70% with respect to a length of the die bearing portion.

  [6] The drawing device for tubular workpieces according to any one of the preceding items 1 to 5, wherein a parallelism of the die bearing portion with respect to a die axis of the drawing die is set within ± 3 °.

  [7] The tubular workpiece drawing apparatus according to any one of the preceding items 1 to 6, wherein the parallelism of the plug bearing portion with respect to the die axis of the drawing die is set within ± 3 °.

  [8] The drawing apparatus for tubular workpieces according to any one of items 1 to 7, wherein the die bearing portion has a length of 5 mm or more.

  [9] Any one of items 1 to 8 above, wherein a step between the workpiece separation position in the first curved surface portion and the die bearing portion in the radial direction of the drawing die is set to be 0.3 mm or more and less than 3 mm. The drawing apparatus for tubular workpieces described in 1.

  [10] The drawing device for tubular workpieces according to any one of the aforementioned Items 1 to 9, wherein the drawing plug includes a third curved surface portion that is smoothly connected to an upstream end of the plug bearing portion.

  [11] The tubular workpiece drawing apparatus according to any one of the preceding items 1 to 10, further comprising a pulling device that pulls the workpiece in the drawing direction so that the drawing speed is in a range of 10 to 100 m / min.

[12] A drawing die for processing the outer surface side of the tubular workpiece,
A first curved surface part that is separated while the workpiece is reduced in diameter;
A die bearing portion disposed on the inner side and downstream side of the workpiece separation position in the first curved surface portion;
A guide portion that has a second curved surface portion smoothly connected to the upstream end of the die bearing portion and guides to the die bearing portion while re-contacting the workpiece away from the first curved surface portion and reducing the diameter of the workpiece. ,
With
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The drawing die, wherein a radius of curvature of the second curved surface portion is set larger than a radius of curvature of the first curved surface portion.

  [13] The drawing die according to item 12, wherein the drawing die is used in combination with a drawing plug that is disposed in a hollow portion of the workpiece and processes the inner surface of the workpiece.

  [14] A method for drawing a tubular workpiece, wherein the tubular workpiece is drawn using the drawing apparatus according to any one of 1 to 11 above.

[15] A method for drawing a tubular workpiece by a drawing apparatus comprising a drawing die for processing the outer surface side of the tubular workpiece, and a drawing plug disposed in the hollow portion of the workpiece and for processing the inner surface side of the workpiece. Because
The drawing die includes a first curved surface portion, a die bearing portion, and a guide portion having a second curved surface portion smoothly connected to the upstream end of the die bearing portion,
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The radius of curvature of the second curved surface portion is set larger than the radius of curvature of the first curved surface portion,
Separating the workpiece from the first curved surface portion while reducing the diameter of the tubular workpiece by the first curved surface portion of the drawing die,
Next, the work is guided to the die bearing part while reducing the diameter by bringing the workpiece into contact with the guide part of the drawing die,
A method of drawing a tubular workpiece, wherein the outer surface of the workpiece is processed by passing the workpiece between the die bearing portion and the plug bearing portion of the extraction plug.

[16] The die bearing portion is disposed on the inner side and the downstream side of the workpiece separation position in the first curved surface portion,
The length of the plug bearing portion is set shorter than the length of the die bearing portion,
16. The method of drawing a tubular workpiece as recited in the aforementioned Item 15, wherein the position of the upstream end of the plug bearing portion is the same as or downstream of the position of the upstream end of the die bearing portion.

  [17] In the cross section including the die axis of the drawing die, the inclination of the tangent line of the first curved surface portion and the inclination of the tangential line of the second curved surface portion with respect to the die axis of the drawing die are respectively in the drawing direction of the workpiece. 17. The method for drawing a tubular workpiece according to the above item 15 or 16, which is gradually reduced as it progresses.

  [18] Any of the above items 15 to 17, wherein the guide portion has an auxiliary curved surface portion that is smoothly connected to an upstream end of the second curved surface portion and is bent in a direction opposite to a bending direction of the second curved surface portion. A method for drawing a tubular workpiece as described in 1 above.

  [19] The method for drawing a tubular workpiece according to any one of the above items 15 to 18, wherein a length of the plug bearing portion is set in a range of 5 to 70% with respect to a length of the die bearing portion.

  [20] The method for drawing a tubular workpiece according to any one of the items 15 to 19, wherein a parallelism of the die bearing portion with respect to a die axis of the drawing die is set within ± 3 °.

  [21] The tubular workpiece drawing method according to any one of items 15 to 20, wherein a parallelism of the plug bearing portion with respect to a die axis of the drawing die is set within ± 3 °.

  [22] The method for drawing a tubular workpiece according to any one of the above items 15 to 21, wherein the die bearing portion has a length of 5 mm or more.

  [23] Any of the preceding items 15 to 22, wherein in the radial direction of the drawing die, a step between the workpiece separation position in the first curved surface portion and the die bearing portion is set to be 0.3 mm or more and less than 3 mm. A method for drawing a tubular workpiece as described in 1 above.

  [24] The tubular workpiece drawing method according to any one of [15] to [23], wherein the drawing plug includes a third curved surface portion smoothly connected to an upstream end of the plug bearing portion.

  [25] The tubular work drawing method according to any one of items 15 to 24, wherein the work is drawn by setting the drawing speed in a range of 10 to 100 m / min.

  The present invention has the following effects.

  According to the drawing apparatus according to the invention of [1], the tubular workpiece is separated from the first curved surface portion so as to be guided toward the guide portion while being reduced in diameter by the first curved surface portion of the drawing die. The workpiece is again brought into contact with the guide portion and is guided to the die bearing portion while being reduced in diameter by the guide portion, and the workpiece passes between the die bearing portion and the plug bearing portion of the extraction plug. Thereby, the inner surface and the outer surface of the workpiece are respectively processed.

  In the material flow of the workpiece as described above, the die bearing portion of the drawing die is disposed on the inner side of the workpiece separation position in the first curved surface portion, so that the workpiece moves from the first curved surface portion to the die bearing portion. It is possible to prevent the workpiece from being excessively reduced in diameter.

  Further, since the second curved surface portion of the guide portion is smoothly connected to the upstream end of the die bearing portion, the work re-contacted with the guide portion smoothly moves toward the die bearing portion through the second curved surface portion. be able to.

  Furthermore, the length of the plug bearing portion of the extraction plug is set to be shorter than the length of the die bearing portion of the extraction die, so that the outer surface of the plug bearing portion and the die bearing portion can be made highly smooth on the workpiece. It is possible to reliably apply the pressure necessary for processing.

  When the above effects act synergistically, the outer surface of the workpiece can be processed into a highly smooth surface.

  Further, since the second curved surface portion is integrally formed at the upstream end of the die bearing portion, it is possible to prevent the axial deviation between the shaft of the second curved surface portion and the shaft of the die bearing portion in the drawing die. Thereby, the coaxiality of the drawing die can be increased. Therefore, the dimensional accuracy of the outer diameter and inner diameter of the drawn pipe can be reliably improved by drawing the workpiece using the drawing apparatus equipped with the drawing die.

  Furthermore, since the curvature radius of the second curved surface portion is set to be larger than the curvature radius of the first curved surface portion, the lubricating oil drawn between the outer surface of the workpiece and the first curved surface portion is used as the outer surface of the workpiece. And the second curved surface portion can be supplied without shortage. Thereby, seizing with the drawing die of the outer surface of a work can be prevented.

  In the invention of [2], it is possible to surely prevent the workpiece from being excessively reduced in diameter while the workpiece re-contacted with the guide portion of the drawing die moves from the guide portion to the die bearing portion, and also to connect the plug bearing portion. Further, the pressure necessary to process the outer surface of the workpiece into a highly smooth surface can be more reliably applied to the work from both portions of the die bearing portion and the die bearing portion. Thereby, the outer surface of a workpiece | work can be reliably processed into a highly smooth surface.

  In the invention of [3], the workpiece can be reliably reduced in diameter by the first curved surface portion, and the workpiece re-contacted with the guide portion can be reliably guided to the die bearing portion by the second curved surface portion.

  In the invention of [4], the guide portion has the auxiliary curved surface portion that is smoothly connected to the upstream end of the second curved surface portion and is bent in the direction opposite to the bending direction of the second curved surface portion. The workpiece away from the portion can be reliably received by the guide portion, so that the workpiece can be reliably guided from the guide portion to the die bearing portion.

  In the invention of [5], when the length of the plug bearing portion is set to 5% or more with respect to the length of the die bearing portion, the outer surface of the plug bearing portion and the die bearing portion can be applied to the workpiece. It is possible to more reliably apply the pressure necessary to process the surface into a highly smooth surface. Thereby, the outer surface of a workpiece | work can be further reliably processed into a highly smooth surface. In addition, since the length of the plug bearing portion is set to 70% or less with respect to the length of the die bearing portion, the work disconnection caused by the contact frictional force between the work and the plug bearing portion is reduced. It can be surely prevented.

  In the invention of [6], the parallelism of the die bearing portion with respect to the die axis of the drawing die is set within ± 3 °, so that the outer surface of the workpiece can be further reliably processed into a highly smooth surface.

  In the invention [7], similarly to the invention [6], the outer surface of the work can be further reliably processed into a highly smooth surface.

  In the invention of [8], the outer surface of the workpiece can be reliably processed into a highly smooth surface.

  In the invention of [9], when the step between the workpiece separation position and the die bearing portion in the first curved surface portion is set to 0.3 mm or more, the workpiece moves from the first curved surface portion to the die bearing portion. It is possible to reliably prevent the workpiece from being excessively reduced in diameter. Further, by setting the step to be less than 3 mm, it is possible to reliably prevent the workpiece from separating from the die bearing portion when the workpiece recontacted with the guide portion is guided to the die bearing portion. Thereby, the outer surface of a workpiece | work can be further reliably processed into a highly smooth surface.

  In the invention of [10], the work contacting the third curved surface portion of the extraction plug can smoothly move toward the plug bearing portion. Thereby, the outer surface of a workpiece | work can be further reliably processed into a highly smooth surface.

  In the invention of [11], the drawing efficiency can be improved by pulling the workpiece by the pulling device so that the drawing speed is 10 m / min or more. In addition, by pulling the work with a pulling device so that the drawing speed is 100 m / min or less, it is possible to prevent the amount of the lubricating oil drawn between the outer surface of the work and the drawing die from being excessively increased. Can do. Thereby, generation | occurrence | production of an oil pit can be prevented further reliably, and the outer surface of a workpiece | work can be further reliably processed into a highly smooth surface.

  The inventions [12] and [13] provide a drawing die that can prevent seizure of the outer surface of the tubular workpiece with the drawing die and that can process the outer surface of the workpiece into a highly smooth surface. it can.

  Further, it is possible to prevent the axial deviation between the axis of the second curved surface part and the axis of the die bearing part in the drawing die. Thereby, the coaxiality of the drawing die can be increased.

  In the invention [14], seizure of the outer surface of the tubular workpiece with the drawing die can be prevented. Furthermore, the outer surface of the workpiece can be processed into a highly smooth surface, and thus a drawn tube having a highly smooth outer surface can be manufactured.

  In the invention of [15], for the same reason as in the invention of [1], seizure of the outer surface of the tubular workpiece with the drawing die can be prevented, and the outer surface of the workpiece is processed into a highly smooth surface. can do.

  Further, it is possible to prevent the axial deviation between the axis of the second curved surface part and the axis of the die bearing part in the drawing die. Thereby, the coaxiality of the drawing die can be increased.

  The inventions [16] to [25] have the same effects as the inventions [2] to [11].

FIG. 1 is a schematic overall view of a tubular workpiece drawing apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the drawing die and the drawing plug in a state where the workpiece is being drawn using the drawing apparatus. FIG. 3 is an enlarged view of FIG. FIG. 4 is a cross-sectional view of a drawing die and a drawing plug in a state in which a workpiece is being drawn using a conventional tubular workpiece drawing apparatus. FIG. 5 is an enlarged view of FIG.

  Next, several embodiments of the present invention will be described below with reference to the drawings.

  1-3 is a figure explaining the drawing processing apparatus for tubular workpieces which concerns on one Embodiment of this invention. In these drawings, reference numeral 10 denotes a drawing apparatus according to this embodiment.

  The drawing apparatus 10 is for drawing a tubular workpiece 40 as shown in FIGS. When the tubular work 40 is drawn by the drawing device 10, the drawn tube 41 is manufactured. The drawing tube 41 is used for a tube that requires the outer surface 41a to be a highly smooth surface, and is suitably used for a photosensitive drum substrate of an electrophotographic apparatus (copying machine, laser beam printer, etc.), for example. Is. A predetermined film such as an OPC (organic photoconductor) film is coated on the outer surface of the photosensitive drum substrate. Therefore, the workpiece 40 can be regarded as a blank for manufacturing a photosensitive drum substrate.

  The workpiece 40 is made of, for example, a metal extruded tube (eg, aluminum extruded tube) obtained by extruding a metal billet (eg, aluminum billet) as a material. The cross-sectional shape of the workpiece 40 is annular. The outer diameter of the workpiece 40 is set to 15 to 50 mm, for example, and the wall thickness is set to 0.5 to 2 mm, for example.

  The material of the workpiece 40 is a metal such as iron, steel, copper, magnesium (including its alloy), aluminum (including its alloy), and particularly preferably aluminum.

  In this embodiment, the diameter reduction rate of the workpiece 40 is set to, for example, 10 to 20%, and the workpiece 40 is drawn by the drawing device 10, whereby the drawing tube 41 having an annular cross section is manufactured. At this time, the thickness of the drawing tube 41 is reduced to, for example, 60 to 90% with respect to the thickness of the workpiece 40.

  The diameter reduction ratio Q of the work 40 (more specifically, the diameter reduction ratio of the outer diameter of the work 40) is D0 as the outer diameter of the work 40 before drawing, and the work 40 after drawing (that is, the drawn pipe 41). When the outer diameter is D1, it is calculated by the following equation (1).

  Q = {1- (D1 / D0)} × 100% (1)

  As illustrated in FIGS. 1 and 2, the drawing apparatus 10 according to the present embodiment employs a plug drawing method instead of an empty drawing method. Therefore, the drawing device 10 includes a drawing tool 11 including a drawing die 20 and a drawing plug 30, and further includes a traction device 12, a lubricating oil supply device 13, and the like.

  The drawing die 20 is for processing the outer surface 40a of the workpiece 40, and is held in a fixed state by a die holder (not shown). The material of the drawing die 20 is cemented carbide, die steel, high speed tool steel, ceramic or the like. The detailed configuration of the drawing die 20 will be described later.

  The extraction plug 30 is disposed in the hollow portion 40 c of the workpiece 40 and processes the inner surface 40 b of the workpiece 40, and is provided in a fixed state at the distal end portion of the support bar 31 that supports the extraction plug 30. . The shape of the extraction plug 30 is substantially spherical or spherical. The material of the drawing plug 30 is cemented carbide, die steel, high-speed tool steel, ceramic or the like. The detailed configuration of the extraction plug 30 will be described later.

  As shown in FIG. 1, the traction device 12 is for traction of the workpiece 40 in the extraction direction N, and includes a chuck portion 12a and a drive source 12b that applies a traction force in the extraction direction N to the chuck portion 12a. ing. The chuck part 12 a chucks the mouth-attaching part 40 d formed at the tip part of the workpiece 40. A hydraulic cylinder or the like is used as the drive source 12b. The drawing direction N of the workpiece 40 is a direction along the die axis X of the drawing die 20.

  The lubricating oil supply device 13 supplies and attaches the drawing lubricating oil 14 to the outer surface 40 a of the workpiece 40, and includes a nozzle 13 a that ejects the lubricating oil 14 toward the outer surface 40 a of the workpiece 40. The nozzle 13 a is disposed on the upstream side of the drawing die 20.

The lubricant 14 is not particularly limited, and specific examples include the trade name “Daphney Master Draw” manufactured by Idemitsu Kosan Co., Ltd., the trade name “Sandrow” manufactured by Sugimura Chemical Co., Ltd., and Kyoei. The product name “Strol” manufactured by Yuka Co., Ltd. is used. The kinematic viscosity of the lubricating oil 14 is not particularly limited, but for example, the kinematic viscosity at 40 ° C. is preferably 300 to 500 mm ² / s.

  The structure of the drawing die 20 is as follows.

  As shown in FIGS. 2 and 3, the drawing die 20 is used in combination with a drawing plug 30 disposed inside the die hole 21, and is connected to the die approach portion 1A and the first curved surface portion 1C. 1B, guide part 2D, die bearing part 2B, and relief part 2E are provided. These parts (1A, 1C, 1B, 2D, 2B, 2E) are sequentially provided in the drawing direction N of the workpiece 40 on the peripheral surface of the die hole 21 of the drawing die 20. Furthermore, these parts are not divided individually but are integrally formed. In addition, the surfaces of these parts are all polished into a mirror surface.

  The die approach portion 1A is formed so that its diameter gradually decreases toward the downstream side in the drawing direction N of the workpiece 40. More specifically, the die approach portion 1A is formed in a conical taper shape.

  The inclination angle of the die approach portion 1A relative to the die axis X of the drawing die 20, that is, the die approach half angle θ1, is set to 20 to 40 °, for example (see FIG. 2).

  The first curved surface portion 1C is formed smoothly and continuously at the downstream end of the die approach portion 1A with respect to the die approach portion 1A. That is, the first curved surface portion 1C has steps and corners at the downstream end of the die approach portion 1A. It is formed continuously so as not to occur. Furthermore, the first curved surface portion 1 </ b> C is formed such that its diameter gradually decreases toward the downstream side in the drawing direction N of the workpiece 40. Further, in the cross section including the die axis X of the drawing die 20, the inclination of the tangent line of the first curved surface portion 1 </ b> C with respect to the die axis X of the drawing die 20 gradually decreases as the workpiece 40 advances in the drawing direction N. The vertical cross-sectional shape of the first curved surface portion 1C is an arc shape. In the present specification, the longitudinal section is a section including the die axis X of the drawing die 20, that is, the section shown in FIGS.

  The curvature radius R1 of the first curved surface portion 1C is set to 1 to 10 mm, for example.

  The die approach portion 1A and the first curved surface portion 1C are portions that first reduce the diameter of the workpiece 40 (specifically, reduce the diameter of the outer surface 40a of the workpiece 40). Further, the first curved surface portion 1 </ b> C is a portion where the workpiece 40 is separated while being reduced in diameter.

  The length L1 in the direction parallel to the die axis X, which is the sum of the die approach portion 1A and the first curved surface portion 1C, is set to 10 to 50 mm, for example.

  Here, the position where the workpiece 40 (more specifically, the outer surface 40a of the workpiece 40) first contacts the die approach portion 1A or the first curved surface portion 1C is defined as “J”. A position where the workpiece 40 is separated from the first curved surface portion 1C while being reduced in diameter is defined as “K”. In the present embodiment, the workpiece 40 is initially in contact with the first curved surface portion 1C, not the die approach portion 1A. In the present invention, the workpiece 40 may first contact the die approach portion 1A.

  The die bearing portion 2B is disposed away from the first curved surface portion 1C on the inner side (that is, on the die axis X side) and downstream of the workpiece separation position K in the first curved surface portion 1C. The die bearing portion 2B is a portion that finishes the outer surface 40a and the outer diameter of the workpiece 40, and is formed substantially parallel to the die axis X.

  The parallelism of the die bearing portion 2B with respect to the die axis X is set within ± 3 °.

  The length L4 of the die bearing portion 2B, more specifically, the length L4 in the direction parallel to the die axis X of the die bearing portion 2B is set to 3 to 15 mm, for example, and preferably set to 5 mm or more. good.

  In the radial direction r of the drawing die 20, the step H1 between the workpiece separating position K and the die bearing portion 2B in the first curved surface portion 1C is set variously, but preferably 0.3 mm or more and less than 3 mm. It is good to be set to.

  The guide portion 2D is a portion that re-contacts with the workpiece 40 (more specifically, the outer surface 40a of the workpiece 40) separated from the first curved surface portion 1C and guides the workpiece 40 to the die bearing portion 2B while reducing the diameter. . The guide portion 2D is formed such that its diameter gradually decreases toward the downstream side in the drawing direction N of the workpiece 40. Here, a position where the workpiece 40 comes into contact with the guide portion 2D again is “M”.

  The guide portion 2D has a second curved surface portion 2C having a circular arc section that is smoothly connected to the die bearing portion 2B at the upstream end F of the die bearing portion 2B, and further upstream of the second curved surface portion 2C. An auxiliary curved surface portion 2A having a circular arc in a longitudinal section that is smoothly connected to the second curved surface portion 2C is provided at the end. Since the guide portion 2D is integrally formed with the die bearing portion 2B, the second curved surface portion 2C of the guide portion 2D is integrally formed with the upstream end F of the die bearing portion 2B.

  In the cross section including the die axis X of the drawing die 20, the inclination of the tangent line of the second curved surface portion 2 </ b> C with respect to the die axis X of the drawing die 20 gradually decreases as the workpiece 40 advances in the drawing direction N. On the other hand, the auxiliary curved surface portion 2A is bent in a direction opposite to the bending direction of the second curved surface portion 2C. Therefore, in the cross section including the die axis X of the drawing die 20, the inclination of the tangent line of the auxiliary curved surface portion 2 </ b> A with respect to the die axis X of the drawing die 20 gradually increases as the workpiece 40 advances in the drawing direction N.

  The length L3 of the guide part 2D in the direction parallel to the die axis X is set to 2 to 5 mm, for example. The curvature radius R21 of the second curved surface portion 2C is set to 1 to 10 mm, for example. The curvature radius R22 of the auxiliary curved surface portion 2A is set to 1 to 10 mm, for example. Furthermore, the curvature radius R21 of the second curved surface portion 2C is set to be larger than the curvature radius R1 of the first curved surface portion 1C (that is, R21> R1). In particular, it is desirable that the curvature radius R21 of the second curved surface portion 2C is set within a range of 1.5 to 2.0 times the curvature radius R1 of the first curved surface portion 1C.

  The connecting portion 1B is a portion that is disposed between the first curved surface portion 1C and the guide portion 2D and connects the first curved surface portion 1C and the guide portion 2D. In the present embodiment, the connecting portion 1B integrally connects the first curved surface portion 1C and the guide portion 2D. Accordingly, the first curved surface portion 1C and the guide portion 2D are integrally formed via the connecting portion 1B. Further, the connecting portion 1B is formed substantially parallel to the die axis X so as not to contact the workpiece 40 during the drawing process. Further, the upstream end of the connecting portion 1B is smoothly connected to the downstream end of the first curved surface portion 1C. Further, the downstream end of the connecting portion 1B is smoothly connected to the upstream end of the guide portion 2D (more specifically, the auxiliary curved surface portion 2A of the guide portion 2D).

  The length L2 of the connecting portion 1B in the direction parallel to the die axis X is set to 3 to 10 mm, for example.

  In the radial direction r of the drawing die 20, the step H2 between the connecting portion 1B and the die bearing portion 2B is set to be equal to or slightly smaller than the step H1 (that is, H2 ≦ H1). However, the difference between H2 and H1 is generally very small. Therefore, although H2 and H1 are strictly different, they may normally be regarded as equal.

  Relief part 2E is a part which forms the work exit part of drawing die 20, and in order to make it not contact with work 40 (drawing pipe 41 in detail), the part toward the downstream side of drawing direction N of work 40 The diameter is formed so as to gradually increase. The inclination angle of the relief portion 2E with respect to the die axis X, that is, the relief half angle θ2 of the relief portion 2E is set to 20 to 40 °, for example (see FIG. 2).

  The length L5 of the relief part 2E in the direction parallel to the die axis X is set to 2 to 10 mm, for example.

  The structure of the extraction plug 30 is as follows.

  The drawing plug 30 is arranged such that its axis coincides with the die axis X of the drawing die 20, and includes a plug approach portion 3A, a third curved surface portion 3C, and a plug bearing portion 3B. These portions (3 </ b> A, 3 </ b> C, 3 </ b> B) are sequentially provided in the drawing direction N of the workpiece 40 on the peripheral surface of the drawing plug 30. Furthermore, these parts are not divided individually but are integrally formed. In addition, the surfaces of these parts are all polished into a mirror surface.

  The plug bearing portion 3B is a portion that finishes the inner surface 40b and the inner diameter of the workpiece 40, and is disposed at a position corresponding to the die bearing portion 2B of the drawing die 20. More specifically, the plug bearing portion 3B faces the die bearing portion 2B. And arranged substantially parallel to the die axis X. Furthermore, the position of the upstream end G of the plug bearing portion 3B is arranged at the same position or downstream of the upstream end F of the die bearing portion 2B in the drawing direction N of the workpiece 40. In FIG. 3, S indicates the amount of shift of the position of the upstream end G of the plug bearing portion 3B to the downstream side with respect to the position of the upstream end F of the die bearing portion 2B. Therefore, as shown in FIG. 3, when the position of the upstream end G of the plug bearing portion 3B is shifted to the downstream side with respect to the position of the upstream end F of the die bearing portion 2B, the sign of the shift amount S is “+ ( Positive) ”. On the contrary, when the position of the upstream end G of the plug bearing portion 3B is shifted to the upstream side, the sign of the shift amount S is “− (negative)”. This deviation amount S is set, for example, in the range of −5 to 5 mm, preferably in the range of −1 to 3 mm, and particularly preferably in the range of 0 to 2 mm. .

  The parallelism of the plug bearing portion 3B with respect to the die axis X is set within ± 3 °.

  The length L6 of the plug bearing portion 3B, more specifically, the length L6 of the plug bearing portion 3B in the direction parallel to the die axis X is set to be shorter than the length L4 of the die bearing portion 2B (ie, L6 < L4). Further, the length L6 is desirably set in a range of 5 to 70% with respect to the length L4 of the die bearing portion 2B, and particularly preferably in a range of 6 to 30%. Dp is the diameter of the plug bearing portion 3B of the extraction plug 30.

  The plug approach portion 3A is formed so that its diameter gradually increases toward the downstream side in the drawing direction N of the workpiece 40. More specifically, the plug approach portion 3A has a conical taper shape.

  The inclination angle of the plug approach portion 3A with respect to the die axis X, that is, the plug approach half angle θ3 is set to 5 to 30 °, for example (see FIG. 2).

  The third curved surface portion 3C is disposed between the plug approach portion 3A and the plug bearing portion 3B, and smoothly connects the plug approach portion 3A and the plug bearing portion 3B. That is, the third curved surface portion 3C is formed at the upstream end G of the plug bearing portion 3B so as to be smoothly connected to the plug bearing portion 3B. Further, a plug approach portion 3A is smoothly formed at the upstream end of the third curved surface portion 3C. In the cross section including the die axis X of the drawing plug 30, the inclination of the tangent line of the third curved surface portion 3 </ b> C with respect to the die axis X gradually decreases as the workpiece 40 advances in the drawing direction N. Specifically, the vertical cross-sectional shape of the third curved surface portion 3C is an arc shape.

  The curvature radius R3 of the third curved surface portion 3C is set to 10 to 60 mm, for example.

  The plug approach portion 3A and the third curved surface portion 3C are in contact with the workpiece 40 (more specifically, the inner surface 40b of the workpiece 40), and guide the third curved surface portion 3C to the plug bearing portion 3B while reducing the thickness of the workpiece 40. It is a part to do. In the present embodiment, the inner surface 40b of the workpiece 40 is initially in contact with the third curved surface portion 3C instead of the plug approach portion 3A. In the present invention, the inner surface 40b of the workpiece 40 may first contact the plug approach portion 3A.

  The method of drawing the tubular workpiece 40 using the drawing device 10 of the present embodiment is substantially the same as the conventional method, and this will be briefly described as follows.

  First, a mouthed portion 40d having a diameter smaller than that of the workpiece 40 is formed at the tip of the tubular workpiece 40 by swaging or the like. Then, the extraction plug 30 is inserted and disposed in the hollow portion 40 c of the workpiece 40, and the tip end portion (that is, the mouth fitting portion 40 d) of the workpiece 40 is inserted into the die hole 21 of the extraction die 20. At this time, the plug bearing portion 3 </ b> B of the extraction plug 30 is disposed at a position corresponding to the die bearing portion 2 </ b> B of the extraction die 20.

  Next, the butt portion 40 d at the tip of the workpiece 40 is chucked by the chuck portion 12 a of the traction device 12. As shown in FIG. 1, the work 40 is supplied so that the lubricating oil 14 is supplied from the nozzle 13 a of the lubricating oil supply device 13 to the outer surface 40 a of the work 40 and the drawing speed is in the range of 10 to 100 m / min. Is pulled in the pulling direction N by the pulling device 12. Thereby, the workpiece 40 is drawn.

  In this drawing process, as shown in FIGS. 2 and 3, the work 40 is guided toward the guide part 2D while being brought into contact with the first curved surface part 1C of the drawing die 20 and being reduced in diameter by the first curved surface part 1C. As shown in FIG. Next, the workpiece 40 is again brought into contact with the guide portion 2D of the drawing die 20 and is guided to the die bearing portion 2B through the second curved surface portion 2C while being reduced in diameter by the guide portion 2D. At this time, the inner surface 40b of the workpiece 40 comes into contact with the third curved surface portion 3C of the extraction plug 30 and is guided from the third curved surface portion 3C to the plug bearing portion 3B.

  Then, when the workpiece 40 passes between the die bearing portion 2B and the plug bearing portion 3B, the outer surface 40a and the inner surface 40b of the workpiece 40 are respectively formed in the die bearing portion 2B so that the thickness of the workpiece 40 is reduced. And it is pressurized by the plug bearing part 3B. As a result, the outer diameter dimension of the workpiece 40 is finished to the target dimension by the die bearing portion 2B, and at the same time, the outer surface 40a of the workpiece 40 is finished to a highly smooth surface by the die bearing portion 2B. At the same time as the inner diameter dimension is finished to the target dimension by the plug bearing portion 3B, the inner surface 40b of the workpiece 40 is finished to the target surface roughness by the plug bearing portion 3B.

  Through the above-described steps, it is possible to obtain a drawn tube 41 having a highly smooth outer surface 41a comparable to that of the polishing process.

  Thus, the drawing apparatus 10 of the present embodiment has the following advantages.

  Since the die bearing portion 2B of the drawing die 20 is disposed on the inner side of the workpiece separating position K in the first curved surface portion 1C, the workpiece 40 is moved while the workpiece 40 moves from the first curved surface portion 1C to the die bearing portion 2B. Can be prevented from being excessively reduced in diameter. As a result, it becomes difficult for severe irregularities to accumulate the lubricating oil 14 to occur on the outer surface 40a of the workpiece 40 [Effect 1].

  Further, since the second curved surface portion 2C of the guide portion 2D is smoothly connected to the upstream end F of the die bearing portion 2B, the workpiece 40 re-contacted with the guide portion 2D passes through the second curved surface portion 2C and the die bearing portion. It can move smoothly toward 2B [Effect 2].

  Further, the length L6 of the plug bearing portion 3B of the drawing plug 30 is set to be shorter than the length L4 of the die bearing portion 2B of the drawing die 20, so that both the plug bearing portion 3B and the die bearing portion 2B are separated from each other. It is possible to reliably give the work 40 the pressure necessary to process the outer surface 40a into a highly smooth surface [Effect 3].

  When the above effects 1 to 3 act synergistically, the outer surface 40a of the workpiece 40 can be processed into a highly smooth surface.

  Further, since the second curved surface portion 2C is integrally formed with the upstream end F of the die bearing portion 2B, the axial displacement between the shaft of the second curved surface portion 2C and the shaft of the die bearing portion 2B in the drawing die 20 is prevented. can do. Thereby, the coaxiality of the drawing die 20 can be increased. Therefore, by drawing the workpiece 40 using the drawing die 20, the dimensional accuracy of the outer diameter and the inner diameter of the drawing tube 41 can be reliably improved. In addition, in the present embodiment, the first curved surface portion 1C, the guide portion 2D, and the die bearing portion 2B of the drawing die 20 are integrally formed. Therefore, the shaft of the first curved surface portion 1C, the shaft of the guide portion 2D, and the die bearing portion. Axis deviation between the 2B axes can be prevented. Thereby, the coaxiality of the drawing die 20 is further increased. Therefore, by drawing the workpiece 40 using the drawing die 20, the dimensional accuracy of the outer diameter and inner diameter of the drawing tube 41 can be further improved.

  Further, since the curvature radius R21 of the second curved surface portion 2C is set to be larger than the curvature radius R1 of the first curved surface portion 1C, the lubrication drawn between the outer surface 40a of the workpiece 40 and the first curved surface portion 1C. The oil 14 can be supplied between the outer surface 40a of the workpiece 40 and the second curved surface portion 2C without being insufficient. Thereby, it is possible to prevent the outer surface 40a of the workpiece 40 from being seized on the drawing die 20 (particularly the second curved surface portion 2C and the die bearing portion 2B of the drawing die 20).

  Furthermore, the position of the upstream end G of the plug bearing portion 3B of the extraction plug 30 is the same as or downstream of the upstream end F of the die bearing portion 2B. As a result, it is possible to reliably prevent the workpiece 40 from being excessively reduced in diameter while the workpiece 40 re-contacted with the guide portion 2D of the drawing die 20 is moved from the guide portion 2D to the die bearing portion 2B, and the plug The pressure required to process the outer surface 40a of the workpiece 40 from both the bearing portion 3B and the die bearing portion 2B into a highly smooth surface can be more reliably applied. Thereby, the outer surface 40a of the workpiece 40 can be reliably processed into a highly smooth surface.

  Further, in the cross section including the die axis X of the drawing die 20, the inclination of the tangent line of the first curved surface portion 1C and the inclination of the tangent line of the second curved surface portion 2C with respect to the die axis X of the drawing die 20 are respectively drawn out of the workpiece 40. As it goes in the direction N, it gradually decreases. Thereby, the diameter of the workpiece 40 can be reliably reduced by the first curved surface portion 1C, and the workpiece 40 re-contacted with the guide portion 2D can be reliably guided to the die bearing portion 2B by the second curved surface portion 2C. it can.

  Furthermore, since the guide portion 2D has the auxiliary curved surface portion 2A that is smoothly connected to the upstream end of the second curved surface portion 2C and is bent in the direction opposite to the bending direction of the second curved surface portion 2C, the first curved surface portion The workpiece 40 separated from 1C can be reliably received by the guide portion 2D, and thus the workpiece 40 can be reliably guided from the guide portion 2D to the die bearing portion 2B.

  Furthermore, when the length L6 of the plug bearing portion 3B of the extraction plug 30 is set to 5% or more with respect to the length L4 of the die bearing portion 2B, both portions of the plug bearing portion 3B and the die bearing portion 2B are provided. Therefore, it is possible to more reliably apply the pressure necessary to process the outer surface 40a of the workpiece 40 into a highly smooth surface. Thereby, the outer surface 40a of the workpiece 40 can be further reliably processed into a highly smooth surface. Further, the length L6 of the plug bearing portion 3B is set to 70% or less with respect to the length L4 of the die bearing portion 2B, thereby causing a contact friction force between the workpiece 40 and the plug bearing portion 3B. The disconnection of the workpiece 40 that occurs can be reliably prevented.

  Furthermore, by setting the parallelism of the die bearing portion 2B with respect to the die axis X of the drawing die 20 to be within ± 3 °, the outer surface 40a of the workpiece 40 can be further reliably processed into a highly smooth surface.

  Furthermore, when the parallelism of the plug bearing portion 3B with respect to the die axis X of the drawing die 20 is set within ± 3 °, the outer surface 40a of the workpiece 40 can be more reliably processed into a highly smooth surface.

  Furthermore, when the length L4 of the die bearing portion 2B of the drawing die 20 is 5 mm or more, the outer surface 40a of the workpiece 40 can be more reliably processed into a highly smooth surface.

  Further, in the radial direction r of the drawing die 20, the step H1 between the workpiece separating position K and the die bearing portion 2B in the first curved surface portion 1C of the drawing die 20 is set to 0.3 mm or more, so that the workpiece It is possible to reliably prevent the workpiece 40 from being excessively reduced in diameter while moving 40 from the first curved surface portion 1C to the die bearing portion 2B. Further, by setting the step H1 to be less than 3 mm, it is possible to reliably prevent the workpiece 40 from separating from the die bearing portion 2B when the workpiece 40 re-contacted with the guide portion 2D is guided to the die bearing portion 2B. be able to. Thereby, the outer surface 40a of the workpiece 40 can be further reliably processed into a highly smooth surface.

  Furthermore, since the extraction plug 30 includes the third curved surface portion 3C that is smoothly connected to the upstream end G of the plug bearing portion 3B, the workpiece 40 in contact with the third curved surface portion 3C is smoothly directed toward the plug bearing portion 3B. Can move. Thereby, the outer surface 40a of the workpiece 40 can be further reliably processed into a highly smooth surface.

  Furthermore, the drawing work efficiency can be improved by pulling the workpiece 40 by the pulling device 12 so that the drawing speed of the drawing tube 41 is 10 m / min or more. Further, by pulling the workpiece 40 by the traction device 12 so that the drawing speed is 100 m / min or less, the amount of the lubricating oil 14 drawn between the outer surface 40a of the workpiece 40 and the drawing die 20 is excessive. The increase can be prevented. Thereby, generation | occurrence | production of an oil pit can be prevented further reliably, and the outer surface 40a of the workpiece | work 40 can be further reliably processed into a highly smooth surface.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to what was shown to the said embodiment, It can change variously.

  In the present invention, between the first curved surface portion 1C and the guide portion 2D of the drawing die 20, one or a plurality of auxiliary bearing portions and diameter reduction processing portions that support the material flow of the workpiece 40 are disposed. May be. Further, in the present invention, even if one or a plurality of auxiliary bearing portions or diameter reduction processing portions that support the material flow of the workpiece 40 are arranged on the upstream side of the first curved surface portion 1C of the drawing die 20. good.

  In the present invention, the drawing tube obtained by drawing by the drawing apparatus according to the present invention is not limited to that used for the photosensitive drum substrate, and can be used for various applications.

  Next, some specific examples and comparative examples of the present invention will be described below. However, the present invention is not limited to the following examples.

  An aluminum tubular work 40 was prepared as a drawing work used in the following examples and comparative examples. The cross-sectional shape of the workpiece 40 is annular. The material of the workpiece 40 is an aluminum alloy equivalent to JIS (Japanese Industrial Standard) A3003, which is one of the materials often used as a material for a drawing work. The workpiece 40 is made of an aluminum extruded tube obtained by extruding an aluminum billet. The work 40 has an outer diameter of 20 mm, an inner diameter of 17 mm, and a wall thickness of 1.5 mm.

<Examples 1-42>
1-3, the drawing speed, the radius of curvature R1 of the first curved surface portion 1C, the radius of curvature R21 of the second curved surface portion 2C of the guide portion 2D, and the plug bearing portion are used. The workpiece 40 was drawn only once by variously changing the displacement amount S of 3B and the length L6 of the plug bearing portion 3B, whereby the drawn tube 41 was manufactured. The outer diameter of the drawing tube 41 is 16.0 mm, its inner diameter is 14.4 mm, and its wall thickness is 0.8 mm. Therefore, the diameter reduction ratio Q of the workpiece 40 is 20%. The lubricating oil 14 used in the drawing process is a trade name “Daphney Master Draw 2594” manufactured by Idemitsu Kosan Co., Ltd. The kinematic viscosity of this lubricating oil 14 at 40 ° C. is 300 to 500 mm ² / s. The supply amount of the lubricating oil 14 to the work outer surface 40a is 1000 g / min. And the surface roughness Ry of the outer surface 41a of the drawing tube 41 was measured, and the surface roughness of the outer surface 41a was evaluated. In addition, ten workpieces 40 were drawn continuously, and the occurrence of seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 during the drawing process was visually evaluated. The results are shown in Tables 1 and 2. In addition, in the “drawing apparatus” column in Tables 1 and 2, a reference numeral “10”, which means the drawing apparatus 10 shown in FIGS.

  The dimensions of the other parts of the drawing die 20 and the drawing plug 30 of the drawing apparatus 10 used in Examples 1-42 are as follows.

  In the drawing die 20, the die approach half angle θ1 = 30 °, the relief half angle θ2 = 20 ° of the relief portion 2E, the length L1 in the direction parallel to the die axis X, which is the sum of the die approach portion 1A and the first curved surface portion 1C = 10 mm, length L2 in the direction parallel to the die axis X of the connecting portion 1B = 6 mm, length L3 = 3 mm in the direction parallel to the die axis X of the guide portion 2D, length L4 = 9 mm of the die bearing portion 2B, relief The length L5 of the part 2E in the direction parallel to the die axis X is 2 mm, and the radius of curvature R22 of the auxiliary curved surface part 2A of the guide part 2D is 2 mm. The curvature radius R1 of the first curved surface portion 1C, the curvature radius R21 of the second curved surface portion 2C, the displacement S of the plug bearing portion 3B, and the length L6 of the plug bearing portion 3B are shown in Tables 1 and 2, respectively. “R1”, “R21”, “Slip amount S of plug bearing portion”, and “Length L6 of plug bearing portion”. In the radial direction r of the drawing die 20, a step H2 between the connecting portion 1B and the die bearing portion 2B = 0.5 mm, and a step H1 between the workpiece separating position K and the die bearing portion 2B in the first curved surface portion 1C = 0.6 mm. Further, the parallelism of the die bearing portion 2B with respect to the die axis X of the drawing die 20 is set within ± 3 °.

  In the drawing plug 30, the diameter Dp of the plug bearing portion 3B = 14.4 mm, the radius of curvature R3 of the third curved surface portion 3C = 50 mm, and the plug approach half angle θ3 = 20 °. When the length L6 of the plug bearing portion 3B is 0, 1, 2, and 5 mm, the ratio of the length L6 of the plug bearing portion 3B to the length L4 of the die bearing portion 2B is 0, 11, 22, and 56%. The parallelism of the plug bearing portion 3B with respect to the die axis X of the drawing die 20 is set within ± 3 °.

  Further, in Tables 1 and 2, “the displacement amount S of the plug bearing portion” indicates the displacement amount S of the upstream end G of the plug bearing portion 3B to the downstream side of the upstream end F position of the die bearing portion 2B. ing. The sign of the deviation amount S is as described above.

  The meanings of the symbols in the “surface roughness” column in Tables 1 and 2 are as follows. The meanings of symbols in the “surface roughness” column in the following Tables 3 to 5 are the same.

A: Ry is 1.0 μm or less (that is, Ry ≦ 1.0 μm)
○: Ry exceeds 1.0 μm and less than 2.0 μm (that is, 1.0 μm <Ry <2.0 μm)
Δ: Ry is 2.0 μm or more (that is, Ry ≧ 2.0 μm)
X: The workpiece was disconnected or could not be drawn.

  The surface roughness Ry of the outer surface 41a of the drawing tube 41 is measured at five locations in the circumferential direction and the length direction of the outer surface 41a of the drawing tube 41 with a laser surface roughness meter (laser probe: 2 μm). These average values were defined as the surface roughness Ry. Moreover, the measurement was performed based on JISB0601: 1994. Ry means the maximum height of the surface roughness.

  Further, the meanings of the symbols in the “burn-in” column in Tables 1 and 2 are as follows. The meanings of the symbols in the “burn-in” column in the following Tables 3 to 5 are the same as this.

○: No seizure occurred Δ: Very small seizure occurred ×: Linear seizure extending in the drawing direction N occurred.

<Comparative Examples 1 and 2>
Except that the length L6 of the plug bearing portion 3B of the drawing plug 30 of the drawing device 10 used in Examples 1-42 is set to 15 mm longer than the length L4 of the die bearing portion 2B, the first to first embodiments. The workpiece 40 was drawn under the same processing conditions as those for the No. 42, whereby the drawn tube 41 was manufactured. And the surface roughness Ry of the outer surface 41a of the drawing tube 41 was measured, and the surface roughness of the outer surface 41a was evaluated. Further, the occurrence of seizure with the drawing die 20 on the outer surface 40a of the workpiece 40 was visually evaluated. The results are shown in Tables 1 and 2.

  As shown in Examples 1 to 42 in Tables 1 and 2, the drawing apparatus 10 of the present embodiment in which the length L6 of the plug bearing portion 3B of the drawing plug 30 is set shorter than the length L4 of the die bearing portion 2B. When the workpiece 40 was drawn using, the outer surface 40a of the workpiece 40 could be processed into a highly smooth surface. Further, when the curvature radius R21 of the second curved surface portion 2C is larger than the curvature radius R1 of the first curved surface portion 1C, the seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 hardly occurred.

  On the other hand, as shown in Comparative Examples 1 and 2, using the drawing apparatus 10 in which the length L6 of the plug bearing portion 3B of the drawing plug 30 is set to be longer than the length L4 of the die bearing portion 2B, the workpiece 40 is formed. When the drawing process was performed, the contact frictional force between the workpiece 40 and the drawing plug 30 was too large, so that the workpiece 40 was seized and the workpiece 40 was disconnected.

<Comparative Examples 3-8>
1-3, the workpiece 40 is drawn by varying the drawing speed, the displacement S of the plug bearing portion 3B, and the length L6 of the plug bearing portion 3B. Thus, the drawn tube 41 was manufactured. And the surface roughness Ry of the outer surface 41a of the drawing tube 41 was measured, and the surface roughness of the outer surface 41a was evaluated. In addition, ten workpieces 40 were drawn continuously, and the occurrence of seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 during the drawing process was visually evaluated. The results are shown in Table 2.

  In the drawing apparatus 10 used in Comparative Examples 3 to 8, the curvature radius R1 of the first curved surface portion 1C of the drawing die 20 and the curvature radius R21 of the second curved surface portion 2C of the guide portion 2D are the same as those of the above-described Examples 1-42. Are different, that is, the curvature radius R1 of the first curved surface portion 1C is 4 mm, and the curvature radius R21 of the second curved surface portion 2C is 4 mm. Other dimensions and drawing conditions of the drawing apparatus 10 are the same as those in Examples 1-42.

  As shown in Table 3, when the workpiece 40 is drawn using the drawing apparatus 10 in which the curvature radius R21 of the second curved surface portion 2C is set equal to the curvature radius R1 of the first curved surface portion 1C, Although the outer surface 40a of 40 can be processed into a highly smooth surface, it has been found that the outer surface 40a of the workpiece 40 may be seized onto the drawing die 20 depending on the drawing speed and other conditions.

<Comparative Examples 9 and 10>
Except that the conventional drawing apparatus 110 shown in FIGS. 4 and 5 was used, the workpiece 40 was drawn under the same processing conditions as in Examples 1-42, thereby producing a drawn tube. And the surface roughness Ry of the outer surface 41a of the drawing tube 41 was measured, and the surface roughness of the outer surface 41a was evaluated. In addition, ten workpieces 40 were drawn continuously, and the occurrence of seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 during the drawing process was visually evaluated. The results are shown in Table 4. In the “Drawing device” column in Table 4, the reference numeral “110”, which means the conventional drawing device 110 shown in FIGS. 4 and 5, is described.

  The dimensions of the other parts of the drawing die 120 and the drawing plug 130 of the drawing apparatus 110 used in Comparative Examples 9 and 10 are as follows.

  In the drawing die 120, the die approach half angle θ1 = 30 °, the relief half angle θ2 = 20 ° of the relief portion 102E, the length L1 = 10 mm in the direction parallel to the die axis X, which is the sum of the die approach portion 101A and the curved surface portion 101C, The length L4 of the die bearing portion 101B is 20 mm, the length L5 of the relief portion 102E in the direction parallel to the die axis X is 2 mm, and the radius of curvature R1 of the curved surface portion 101C is 4 mm.

  In the drawing plug 130, the diameter Dp of the plug bearing portion 103B = 14.4 mm, the length L6 = 2 mm of the plug bearing portion 103B, and the curvature radius R3 = 50 mm of the curved surface portion 103C between the plug bearing portion 103B and the plug approach portion 103A. The plug approach half angle θ3 = 18 °, and the displacement S of the plug bearing portion 103B is S = 2 mm. The displacement amount S of the plug bearing portion 103B is a displacement amount of the upstream end G of the plug bearing portion 103B to the downstream side with respect to the upstream end F of the die bearing portion 101B.

  As shown in Table 4, when the workpiece 40 was drawn using the conventional drawing apparatus 110, seizure of the outer surface 40a of the workpiece 40 with the drawing die 120 did not occur. The surface roughness of the outer surface 40a of the work 40 was worse than when the work 40 was drawn using the form drawing apparatus 10.

<Examples 43 to 47>
The drawing apparatus 10 according to the present embodiment shown in FIGS. 1 to 3 is used to draw the workpiece 40 by varying the drawing speed and the displacement amount S of the plug bearing portion 3B, thereby drawing the pipe 41. Manufactured. And the surface roughness Ry of the outer surface 41a of the drawing tube 41 was measured, and the surface roughness of the outer surface 41a was evaluated. In addition, ten workpieces 40 were drawn continuously, and the occurrence of seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 during the drawing process was visually evaluated. The results are shown in Table 5.

  In the drawing apparatus 10 used in Examples 43 to 47, the step H1 between the workpiece separating position K and the die bearing part 2B in the first curved surface part 1C of the drawing die 20 is different from those in Examples 1 to 42. That is, the steps H1 = 1.1 mm and H2 = 1.0 mm. Other dimensions and drawing conditions of the drawing apparatus 10 are the same as those in Examples 1-42.

  As shown in Table 5, the present embodiment in which the step H1 between the workpiece separation position K and the die bearing portion 2B in the first curved surface portion 1C of the drawing die 20 is set to be different from those in Examples 1-42. Even when the workpiece 40 is drawn using the drawing apparatus 10, the outer surface 40a of the workpiece 40 can be processed into a highly smooth surface, and seizure of the outer surface 40a of the workpiece 40 with the drawing die 20 can be prevented. Could be confirmed.

  INDUSTRIAL APPLICABILITY The present invention can be used for a tubular workpiece drawing apparatus, a drawing die, and a tubular workpiece drawing method.

10: Drawing device 12: Pulling device 20: Drawing die 1A: Die approach portion 1B: Connecting portion 1C: First curved surface portion 2A: Auxiliary curved surface portion 2B: Dice bearing portion 2C: Second curved surface portion 2D: Guide portion 30: Drawing plug 3A: Plug approach portion 3B: Plug bearing portion 3C: Third curved surface portion 40: Work piece 40a: Outer surface 41: Pulling tube 41a: Outer surface X: Die axis N of drawing die N: Work drawing direction

Claims (24)

A drawing die for processing the outer surface side of the tubular workpiece, and a drawing plug disposed in the hollow portion of the workpiece and for processing the inner surface side of the workpiece,
The drawing die is
A first curved surface part that is separated while the workpiece is reduced in diameter;
A die bearing portion disposed on the inner side and downstream side of the workpiece separation position in the first curved surface portion;
A guide portion that has a second curved surface portion smoothly connected to the upstream end of the die bearing portion and guides to the die bearing portion while re-contacting the workpiece away from the first curved surface portion and reducing the diameter of the workpiece. ,
With
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The radius of curvature of the second curved surface portion is set larger than the radius of curvature of the first curved surface portion,
The drawing work apparatus for a tubular workpiece, wherein the drawing plug includes a plug bearing portion that is disposed at a position corresponding to the die bearing portion and is shorter than the length of the die bearing portion.   2. The tubular workpiece drawing apparatus according to claim 1, wherein the position of the upstream end of the plug bearing portion is the same as or downstream of the position of the upstream end of the die bearing portion.   In the cross section including the die axis of the drawing die, the inclination of the tangential line of the first curved surface portion and the inclination of the tangential line of the second curved surface portion with respect to the die axis of the drawing die are gradually increased in the workpiece drawing direction. The drawing apparatus for tubular workpieces according to claim 1 or 2, wherein the drawing apparatus is small.   The said guide part has an auxiliary | assistant curved surface part which continued to the upstream end of the said 2nd curved surface part smoothly, and was bent in the direction opposite to the bending direction of a 2nd curved surface part. Drawing machine for tubular workpieces.   The length of the said plug bearing part is a 5-70% range with respect to the length of the said die bearing part, The drawing processing apparatus for tubular workpieces in any one of Claims 1-4.   6. The drawing apparatus for tubular workpieces according to claim 1, wherein a parallelism of the die bearing portion with respect to a die axis of the drawing die is set within ± 3 °.   The tubular workpiece drawing apparatus according to any one of claims 1 to 6, wherein a parallelism of the plug bearing portion with respect to a die axis of the drawing die is set within ± 3 °.   The length of the said die bearing part is 5 mm or more, The drawing processing apparatus for tubular workpieces in any one of Claims 1-7.   The step between the workpiece separation position in the first curved surface portion and the die bearing portion in the radial direction of the drawing die is set to be 0.3 mm or more and less than 3 mm. Drawing machine for tubular workpieces.   The said drawing plug is a drawing apparatus for tubular works in any one of Claims 1-9 provided with the 3rd curved surface part connected with the upstream end of the said plug bearing part smoothly.   The drawing apparatus for tubular workpieces according to any one of claims 1 to 10, further comprising a pulling device that pulls the workpiece in the drawing direction so that the drawing speed is in a range of 10 to 100 m / min. A drawing die that is disposed in a hollow portion of a tubular workpiece and is used in combination with a drawing plug that processes the inner surface of the workpiece, and that processes the outer surface side of the workpiece,
A first curved surface part that is separated while the workpiece is reduced in diameter;
A die bearing portion disposed on the inner side and downstream side of the workpiece separation position in the first curved surface portion;
A guide portion that has a second curved surface portion smoothly connected to the upstream end of the die bearing portion and guides to the die bearing portion while re-contacting the workpiece away from the first curved surface portion and reducing the diameter of the workpiece. ,
With
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The radius of curvature of the second curved surface portion is set larger than the radius of curvature of the first curved surface portion ,
The drawing die is characterized in that the drawing plug is provided at a position corresponding to the die bearing portion and has a plug bearing portion shorter than the length of the die bearing portion .   A method for drawing a tubular workpiece, wherein the tubular workpiece is drawn using the drawing apparatus according to claim 1. A method of drawing a tubular workpiece by a drawing apparatus comprising a drawing die for processing the outer surface side of the tubular workpiece, and a drawing plug disposed in the hollow portion of the workpiece and for processing the inner surface side of the workpiece. ,
The drawing die includes a first curved surface portion, a die bearing portion, and a guide portion having a second curved surface portion smoothly connected to the upstream end of the die bearing portion,
The second curved surface portion is integrally formed at the upstream end of the die bearing portion,
The radius of curvature of the second curved surface portion is set larger than the radius of curvature of the first curved surface portion,
The extraction plug is provided at a position corresponding to the die bearing portion and includes a plug bearing portion shorter than the length of the die bearing portion,
Separating the workpiece from the first curved surface portion while reducing the diameter of the tubular workpiece by the first curved surface portion of the drawing die,
Next, the work is guided to the die bearing part while reducing the diameter by bringing the workpiece into contact with the guide part of the drawing die,
A method of drawing a tubular workpiece, wherein the outer surface of the workpiece is processed by passing the workpiece between the die bearing portion and the plug bearing portion of the extraction plug. The die bearing portion is disposed on the inner side and the downstream side of the workpiece separating position in the first curved surface portion,
The tubular workpiece drawing method according to claim 14 , wherein the position of the upstream end of the plug bearing portion is the same as or downstream of the position of the upstream end of the die bearing portion. In the cross section including the die axis of the drawing die, the inclination of the tangential line of the first curved surface portion and the inclination of the tangential line of the second curved surface portion with respect to the die axis of the drawing die are gradually increased in the workpiece drawing direction. The tubular workpiece drawing method according to claim 14 or 15 , wherein the tubular workpiece is reduced in size. The guide portion, according to any one of claims 14 to 16 to the bending direction of the smoothly contiguous and the second curved surface to the upstream end of the second curved portion has an auxiliary curved portion bent in the opposite direction Drawing method of tubular work. 18. The method of drawing a tubular workpiece according to claim 14 , wherein a length of the plug bearing portion is set in a range of 5 to 70% with respect to a length of the die bearing portion. The tubular workpiece drawing method according to any one of claims 14 to 18 , wherein a parallelism of the die bearing portion with respect to a die axis of the drawing die is set within ± 3 °. The tubular workpiece drawing method according to any one of claims 14 to 19 , wherein a parallelism of the plug bearing portion with respect to a die axis of the drawing die is set within ± 3 °. The length of the said die bearing part is 5 mm or more, The drawing process method of the tubular workpiece in any one of Claims 14-20 . In the radial direction of the drawing die, the step between the workpiece away position and the die bearing section of the first curved surface portion, according to any one of claims 14 to 21 which is set to less than than 0.3 mm 3 mm Drawing method of tubular work. The method of drawing a tubular workpiece according to any one of claims 14 to 22 , wherein the drawing plug includes a third curved surface portion smoothly connected to an upstream end of the plug bearing portion. The tubular workpiece drawing method according to any one of claims 14 to 23 , wherein the workpiece is drawn by setting a drawing speed in a range of 10 to 100 m / min.