Drawing processing device and drawing processing method

Abstract

To efficiently manufacture drawn material by simplifying or omitting a straightening process of the drawn material in a drawing device and a drawing method for performing drawing processing for passing raw material through a forming hole of a die.SOLUTION: A device and a method are configured to covey raw material W along a conveyance path 2, to insert the raw material W into a forming hole 6 of a die 5 located on the conveyance path 2 from an upstream side, to pull out the raw material W into a downstream side of the forming hole 6, and to form a specified outer circumference shape, where the conveyance path 2 is provided with an eccentric device (entry-side guide device 11) that brings an axial core C1 of the raw material W into an eccentric state in which the axial core is shifted or inclined with respect to a reference straight line T1 that overlaps a straight imaginary axial core, and the eccentric device changes a direction of shift or inclination of the axial core C1 along a circumferential direction around the reference straight line T1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drawing processing apparatus and a drawing processing method.

Background Art

[0002] Conventionally, a drawing processing apparatus and a drawing processing method are known in which a long material (bar, wire, tube) is drawn through a forming hole of a die, and the outer peripheral shape of the material is changed according to the shape of the forming hole (see, for example, Patent Documents 1 and 2). The drawing process includes a plurality of straightening processes. For example, in Fig. 1 of Patent Document 1 and the like, it is described that after the material is drawn, it is straightened through a three-stage straightening process of spinner straightening, straightening with centerless grinding, and two-roll straightening. For example, in Fig. 2 of Patent Document 2 and the like, it is described that after the material is drawn, it is straightened through two stages of spinner straightening and two-roll straightening.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

[0004] In the conventional drawing process using a die, the issue is to ensure the straightness of the material (drawn material) after drawing. That is, the occurrence of bending is inevitable in the drawn material after drawing because the material before drawing remains bent, and the reciprocating movement line of the chuck when drawing the material from the die does not necessarily coincide with the axis of the die. When the drawing direction and the axis of the die are different, the drawing is performed in a direction having an angle with the axis of the die, and as a result, the drawing is performed in a bent state, and a difference occurs in the contact length between the material and the die on the back side and the ventral side of these bends. For this reason, the material is stretched more on the side with the shorter contact length, and bending occurs in the drawn material after drawing. In addition, when the die itself is not completely symmetrical, bending of the drawn material is also a cause of bending. In order to remove the bending of the drawn material, a straightening process is carried out after the drawing process, but as described above, the straightening process has multiple stages, so it is desired to develop a technology that improves the straightness of the drawn material to reduce the number of steps required for straightening or to make the straightening process unnecessary. In other words, if the bending after drawing can be suppressed, it is expected that it will be possible to simplify the adjustment of straightening conditions, simplify the straightening process, and even omit the straightening process altogether.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to simplify or omit the straightening process of the drawn material in a drawing device and a drawing method for passing a material through a forming hole of a die, and to efficiently manufacture the drawn material.

Means for Solving the Problems

[0006] As a means for solving the above problems, a first aspect of the present invention is a drawing device that conveys a material along a conveyance path, inserts this material into a forming hole of a die in the conveyance path from the upstream side, and draws it to the downstream side of the forming hole to form a specified outer peripheral shape. In the conveyance path, an eccentric device is provided that makes the axis of the material in an eccentric state shifted or inclined with respect to a reference straight line that overlaps with a straight virtual axis. The eccentric device provides a drawing device that changes the direction of the shift or inclination of the axis along the circumferential direction centered on the reference straight line. According to this configuration, in a drawing device that conveys a long material such as a bar, wire, or tube along a conveyance path and draws it while reducing the diameter using a die to obtain a drawn material, an eccentric device that shifts or inclines the axis of the material is provided in the conveyance path including the die. By changing the direction of the shift or inclination of the axis so that it rotates around the reference straight line, the straightness of the drawn material can be further improved. That is, even if the material is bent or there is a shift or inclination with respect to the axis of the die in the drawing direction, intentionally causing eccentricity in the material at the inlet side, outlet side, or in the die of the die, and changing the eccentric direction so as to rotate, the following effects can be obtained. First, in the drawing process, when the material enters the die obliquely with respect to the die axis on the die inlet side, a difference occurs in the contact length between the material and the die. When a difference appears in the contact length, the side with the shorter contact length is stretched more than the side with the longer contact length. For this reason, the drawn material bends in a shape where the side with the shorter contact length is on the back (this bend is defined as a forward bend). On the other hand, when the direction in which the material obliquely travels is reversed by the operation of the eccentric device, a reverse bend occurs in the drawn material (this bend is defined as a reverse bend). By repeatedly reversing the direction of the material's skew during the drawing process, a drawn material with alternating forward and reverse bends is obtained. From a macroscopic perspective, this drawn material can be said to be nearly straight. In particular, the eccentricity device of the present application changes the direction of deviation or inclination of the axis along the circumferential direction centered on a reference straight line, so that the drawn material has the following configuration compared to a case in which the direction of inclination is reversed from forward to reverse: That is, instead of a configuration in which forward and reverse bends are simply continuous, a configuration in which forward to reverse and reverse to forward bends are smoothly connected is achieved, and the straightness of the drawn material can be further improved. In this way, according to the present invention, by repeatedly rotating the direction of the skew of the material during drawing, it is possible to actively utilize the bending of the drawn material due to the difference in the contact length between the material and the die, thereby suppressing the occurrence of macroscopic bending and obtaining a drawn material that is nearly straight. As a result, it is possible to simplify or omit the process of straightening the drawn material and efficiently manufacture the drawn material.

[0007] In a second aspect of the present invention, in the first aspect described above, an eccentric device is provided on at least one of the entrance and exit sides of the die in the conveying path, which displaces the axis of the material from a reference line and changes the direction of the axis deviation in a circumferential direction around the reference line. According to this configuration, by rotating the material around the reference straight line center, the eccentric device can repeatedly bend and unbend the material. When the eccentric device is provided on the entry side of the die, the material can be passed through the die while the initial curvature (bending) of the material disappears. This makes it possible to prevent the initial curvature of the material from remaining in the drawn material. When the eccentric device is provided on the exit side of the die, even if the drawn material is prone to curvature (bending) due to the initial curvature (bending) of the material or a misalignment or inclination with respect to the die axis in the drawing direction, the drawn material can be repeatedly bent back directly at the exit side of the die to prevent the curvature from remaining in the drawn material.

[0008] In a third aspect of the present invention, in the first aspect described above, an eccentric device is provided on at least one of the entrance and exit sides of the die in the conveying path, which displaces the axis of the material from a reference line and changes the direction of the axis deviation along a circumferential direction centered on the reference line, and a holding device is positioned further from the die than the eccentric device and holds the material on the reference line. According to this configuration, in addition to the effect of the second embodiment, by providing an eccentric device and a holding device on at least one of the entry side and exit side of the die, the material with the free end side restrained can be repeatedly bent and unbended stably by the eccentric device. In other words, the eccentric device prevents the free end side of the material from whirling when the eccentric device rotates the material in the eccentric direction, and the material can be repeatedly bent and unbended in a stable manner.

[0009] In a fourth aspect of the present invention, in the first aspect described above, the eccentric device puts the axis of the die in an eccentric state inclined with respect to a reference line, and changes the direction of inclination of the axis along a circumferential direction centered on the reference line. According to this configuration, the axial center of the die through which the material passes is inclined with respect to a reference straight line, and the direction of the inclination of the axial center of the die is rotated around the reference straight line, so that the material can be repeatedly bent and unbended. In other words, even if the material is bent or there is a deviation or inclination with respect to the axial center of the die in the drawing direction, the material is intentionally made eccentric in the die and the eccentric direction is changed so as to rotate, so that the occurrence of bending of the drawn material due to the difference in contact length between the material and the die is actively utilized, and the occurrence of macroscopic bending is suppressed, and a drawn material that is nearly straight can be obtained. As a result, the correction process of the drawn material can be simplified or omitted, and the drawn material can be efficiently manufactured.

[0010] A fifth aspect of the present invention provides a drawing method in which a material is transported along a conveying path, the material is inserted from the upstream side into a forming hole of a die located on the conveying path, and drawn out to the downstream side of the forming hole to form a specified outer peripheral shape, in which the material is drawn out while performing an eccentric operation in which the axis of the material is shifted or tilted relative to a reference line that overlaps with a straight imaginary axis, on a conveying path including the die, and a rotational operation that changes the direction of the shift or tilt of the axis along the circumferential direction centered on the reference line. Effect of the Invention

[0011] According to the present invention, in a drawing apparatus and a drawing method for performing drawing by passing a material through a forming hole in a die, it is possible to simplify or omit the correction process for the drawn material, thereby making it possible to efficiently produce drawn material. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic explanatory diagram of a drawing device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. 4 is a schematic explanatory diagram of a drawing device according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a schematic explanatory diagram of a drawing device according to a third embodiment of the present invention. [Figure 5A] FIG. 5 is a partially enlarged view of FIG. 4, showing the die tilted upward in the drawing. [Figure 5B] FIG. 5 is a partially enlarged view of FIG. 4, showing the dice tilted downward in the drawing. [Figure 6] FIG. 2 is a front view of an experimental device for the drawing apparatus. [Figure 7] FIG. 2 is a cross-sectional view of the main body of the experimental device. [Figure 8] FIG. 8 is a view taken along line VIII in FIG. 7, showing a guide device for the experimental apparatus. [Figure 9] FIG. 9 is a view taken along the arrow corresponding to FIG. 8, showing a state in which the guide device of the experimental apparatus is rotated in an eccentric state. [Figure 10] FIG. 13 is an explanatory diagram showing how the material is offset and inserted into a die in the experimental device. [Figure 11] FIG. 11 is a cross-sectional view showing a modified example of the main body of the experimental device. [Figure 12] 1 is a graph showing the experimental results of the above-mentioned experimental device, in which the vertical axis indicates the curvature of the material, and the horizontal axis indicates the measurement range of the curvature of the material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment of the present invention will be described below with reference to the drawings, but the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. The term "middle" used in this embodiment includes not only the center between both ends of an object, but also an inner part and a predetermined range between both ends of an object.

[0014] Fig. 1 is an explanatory diagram showing an outline of a drawing apparatus 1A of a first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1 (an explanatory diagram for the operation of an inlet guide device 11, which will be described later). The drawing apparatus 1A is used to manufacture drawn materials by reducing the outer diameter of a long material (workpiece) W such as a bar, wire, or tube to a specified outer diameter. The drawing apparatus 1A transports the long material W along a transport path 2 extending in the left-right direction in the figure. The left side of the transport path 2 in the figure is the upstream side, and the right side is the downstream side. Line T1 in the figure indicates a reference line that extends along the transport direction and overlaps with a virtual axis center when the material W is straight. In the figure, the Z axis indicates the transport direction that overlaps with the reference line T1, the Y axis indicates the direction perpendicular to the Z axis (the up-down direction on the figure), and the X axis indicates the direction perpendicular to the Y axis and the Z axis (the front-back direction perpendicular to the figure).

[0015] The conveying path 2 is provided with a material feeding device 3, a die 5, and a material pulling device 7 in this order from the upstream side to the downstream side. The material feed device 3 uses rollers or the like to feed the material W of a specified length, whose tip has been subjected to a narrowing process, downstream in the conveying direction. The material feed device 3 of the first embodiment is provided with an entry guide device 11 that applies displacement in the X and Y directions perpendicular to the conveying direction to the intermediate portion of the material W in the longitudinal direction. The entry guide device 11 includes an eccentric mechanism that shifts the axis C1 of the material W in at least one of the X and Y directions relative to a reference line T1 to make it eccentric, and a rotation mechanism that rotates the direction of the shift of the axis C1 around the reference line T1.

[0016] The entry-side guide device 11 includes a guide member 12 that holds the raw material W by pinching it from at least both radial sides. The entry-side guide device 11 can move the guide member 12 holding the raw material W by operating an eccentric mechanism so that the axis C1 of the raw material W is displaced in at least one of the X direction and Y direction or obliquely with respect to the reference straight line T1. 2, the inlet guide device 11 can rotate the guide member 12, which holds and displaces the material W as described above, about the reference line T1 by operating the rotation mechanism. At this time, the axis C1 of the material W rotates about the reference line T1, changing the eccentric direction of the material W. The guide member 12 may be rotated manually, for example, every time a predetermined amount is drawn out, or automatically by a drive source and a control device (not shown).

[0017] Note that the guide member 12 is not limited to being rotated by a rotating mechanism, and may be configured, for example, so that the guide member 12 moves circumferentially in parallel along the XY plane. The guide member 12 may also be configured to tilt the axis C1 of the material W with respect to the reference line T1, and the guide member 12 may be configured to swing around a fulcrum on the reference line T1. With these configurations, the direction of deviation or tilt of the axis C1 can be changed so that the material W rotates around the reference line T1. In these configurations, the guide member 12 may be configured to hold the material W from three or more sides in the circumferential direction.

[0018] The material feed device 3 of the first embodiment is provided with an entry-side holding device 15 that holds the axis C1 of the material W on the reference line T1, located upstream of the entry-side guide device 11 in the conveying direction (the side away from the die 5). The entry-side holding device 15 is provided with a holding member 16 that holds the material W by pinching it from at least both radial sides. The holding member 16 may have the same configuration as the guide member 12 of the entry-side guide device 11, for example. The holding member 16 is immovable with respect to the conveying path 2, for example, and fixes the axis C1 of the material W on the reference line T1 at the installation position of the entry-side holding device 15. The holding member 16 may hold the material W with a gap. For example, the entry-side holding device 15 may be configured to hold the material W with a margin that allows at least a part of the material W to be positioned on the reference line T1 at the installation position.

[0019] The die 5 is made of a material such as metal or metal carbide that is harder than the material W to be processed. The die 5 is substantially cylindrical, and a forming hole 6 is formed in the center along the axis C2, through which the rod-shaped material W is inserted to reduce the diameter. The forming hole 6 has a tapered portion 6a formed on the upstream side of the die 5 in the conveying direction such that the inner diameter becomes wider toward the upstream side, and a small diameter portion 6b formed to have a constant inner diameter on the downstream side of the die 5 in the conveying direction.

[0020] The upstream end of the tapered portion 6a in the conveying direction forms an upstream opening with a larger diameter than the processing target portion Wb of the material W (excluding the narrowed portion Wa) on the side surface of the die 5 on the upstream side in the conveying direction. A small diameter portion 6b of the same diameter as this end is continuous with the downstream end of the tapered portion 6a in the conveying direction. The downstream end of the small diameter portion 6b in the conveying direction forms a downstream opening with a smaller diameter than the upstream opening on the side surface of the die 5 on the downstream side in the conveying direction. A chamfer 6c is applied to the periphery of the downstream opening. The boundary portion between the cylindrical inner surface of the small diameter portion 6b and the inner surface of the chamfer 6c is located at the die exit point O described later.

[0021] The inner diameter of the cylindrical inner peripheral surface of the small diameter portion 6b is smaller than the outer diameter of the processing target portion Wb of the raw material W. When the raw material W is inserted into this small diameter portion 6b via the tapered portion 6a and pulled out, the processing target portion Wb of the raw material W is ironed by the tapered portion 6a and plastically deformed so as to reduce in diameter, and the outer peripheral surface is smoothed and adjusted to a constant outer diameter by the small diameter portion 6b, so that a drawn material having a specified cross-sectional shape can be obtained.

[0022] The material pulling device 7 is equipped with a chuck 8 that grips the narrowed portion Wa protruding downstream in the conveying direction of the forming hole 6 of the die 5, and a drive mechanism (not shown) that reciprocates the chuck 8 along the conveying direction. At the beginning of the drawing process, the chuck 8 is located at the upstream end of the reciprocating range, and multiple holding claws bite and grip the narrowed mouth portion Wa of the material W that protrudes downstream in the conveying direction of the die 5. The chuck 8 holding the narrowed mouth portion Wa moves from the upstream end to the downstream end of the reciprocating range, and pulls the material W inserted into the forming hole 6 of the die 5 from the forming hole 6. When the chuck 8 reaches the downstream end of the reciprocating range in the conveying direction, it opens its holding claws and releases the narrowed mouth portion Wa, and in that state returns to the upstream end of the reciprocating range in the conveying direction and bites and grips the material W again. By repeating this process, it is possible to continuously pull out the long material W downstream in the conveying direction.

[0023] Referring to FIG. 1, in the drawing apparatus 1A of the first embodiment, an entry guide device 11 (material eccentric device) is provided upstream of the die 5 in the conveying direction. In the conveying direction, an entry holding device 15 (material whirling prevention device) is provided upstream of the entry guide device 11 in the conveying direction (opposite the die 5) at a position a distance β away from the entry guide device 11. In the conveying direction, the position of the entry holding device 15 on the reference line T1 is the entry holding point A, the position of the entry guide device 11 on the reference line T1 is the rolling point B, and the contact position of the die 5 and the material W on the reference line T1 is the die exit point O. The distance between the die exit point O and the rolling point B is α, and the distance between the rolling point B and the entry holding point A is β. The amount of eccentricity of the shaft center C1 at the position of the rolling point B is indicated by δ.

[0024] An entry-side holding device 15 is provided upstream of the entry-side guide device 11 in the conveying direction to fix the position of the axis C1 of the material W so that the axis C1 coincides with the Z-axis. When the guide member (material holder) 12 of the entry-side guide device 11 rotates about the axis C2 of the die 5 (center of the Z-axis, center of the reference line T1), the axis C1 of the material W rotates with a radius δ at the rolling point B (see FIG. 2). As a result, the operation of rotating the skew direction of the material W is repeated during the drawing process, and the occurrence of bending of the drawn material due to the difference in contact length between the material W and the die 5 is actively utilized, making it possible to suppress the occurrence of macroscopic bending and obtain a drawn material that is nearly straight.

[0025] FIG. 3 is an explanatory diagram showing an outline of a drawing apparatus 1B of the second embodiment. In the drawing apparatus 1B of the second embodiment, an exit guide device 13 (material eccentric device) is provided downstream of the die 5 in the conveying direction. In the conveying direction, an exit holding device 17 (material whirling prevention device) is provided downstream of the exit guide device 13 in the conveying direction (opposite the die 5) at a position a distance α' away from the exit guide device 13. In the figure, reference numeral 18 indicates a holding member of the exit holding device 17. In the conveying direction, the position of the exit holding device 17 on the reference line T1 is the exit holding point A', the position of the exit guide device 13 on the reference line T1 is the rolling point B', and the contact position of the die 5 and the material W on the reference line T1 is the die exit point O. The distance between the die exit point O and the rolling point B' is β', and the distance between the rolling point B' and the exit holding point A' is α'. The eccentricity of the axis C1 at the position of the rolling point B' is indicated by δ'.

[0026] An exit-side holding device 17 is provided downstream of the exit-side guide device 13 in the conveying direction to fix the position of the axis C1 of the material W so that the axis C1 coincides with the Z-axis. When a guide member (material holder) 14 of the exit-side guide device 13 rotates about the axis C2 of the die 5 (center of the Z-axis, center of the reference line T1), the axis C1 of the material W rotates with a radius δ at the rolling point B'. As a result, the operation of rotating the skew direction of the material W is repeated during the drawing process, and the occurrence of bending of the drawn material due to the difference in contact length between the material W and the die 5 is actively utilized, thereby suppressing the occurrence of macroscopic bending and obtaining a drawn material that is nearly straight.

[0027] In the embodiment, a movable device (entry-side guide device 11 or exit-side guide device 13) is provided at one of the locations on the conveying path 2 that are farther away from the die 5 on the entry side or the exit side, but movable devices may be provided at both the entry side and the exit side. That is, in the embodiment, it is sufficient that a movable device (entry-side guide device 11 or exit-side guide device 13) is provided at least at one of the entry side or the exit side of the die 5.

[0028] FIG. 4 is an explanatory diagram showing an outline of a drawing apparatus 1C according to the third embodiment. In the drawing apparatus 1C of the third embodiment, an entry-side holding device 15 and an exit-side holding device 17 are provided upstream and downstream in the conveying direction from the die 5. In the conveying direction, the entry-side holding device 15 is provided at a position spaced a distance η upstream from the die 5 in the conveying direction, and the exit-side holding device 17 is provided at a distance κ downstream from the die 5 in the conveying direction.

[0029] In the conveying direction, the position on the reference line T1 of the entry-side holding device 15 is defined as entry-side holding point C, the position on the reference line T1 of the exit-side holding device 17 is defined as exit-side holding point D, and the contact position on the reference line T1 between the die 5 and the material W is defined as die exit-side point O. The distance between the entry-side holding point C and the die exit-side point O is defined as η, and the distance between the die exit-side point O and the exit-side holding point D is defined as κ. An entry side holding device 15 and an exit side holding device 17 are provided on the upstream side and downstream side of the die 5 in the conveying direction, respectively, for fixing the position of the axis C1 of the material W so that the axis C1 coincides with the Z axis.

[0030] The die 5 is supported by a die movable device 19 (material eccentric device). The die movable device 19 is equipped with an eccentric mechanism that tilts the axis C2 of the die 5 to an eccentric state with respect to the reference line T1. The eccentric mechanism is provided so that the die 5 can oscillate around a fulcrum on the reference line T1. The oscillating motion here means that the axis C2 of the die 5 is inclined with respect to the reference line T1, and the direction of this inclination changes successively over 360° in the circumferential direction. The die 5 itself does not need to rotate (it may oscillate around the Z axis), as long as the direction of inclination changes. This makes it possible to change the direction of inclination of the axis C2 of the die 5 so that it rotates around the reference straight line T1, and therefore makes it possible to similarly change the direction of inclination of the axis C1 of the material W.

[0031] 11 shows a lifting assembly 113' capable of the above-mentioned swivel motion as a modified example of the lifting assembly 113 (see FIGS. 6 and 7) of the experimental apparatus 100 described below. In the experimental apparatus 100, the pulling direction of the material W (and the reference line T1) is oriented vertically. The lifting assembly 113' includes a die 5 and a die case 114' that houses the die 5. The die case 114' includes a lower portion 114b that is fixed to the lifting table 105 side, and an upper portion 114a that is supported above the lower portion 114b via a bearing 114c. The upper portion 114a is supported rotatably around a reference line T1 relative to the lower portion 114b. The die 5 is supported inside the upper portion 114a via a bearing 114d. The bearing 114d and the die 5 are supported in an inclined position on the bottom surface of the upper portion 114a. The die 5 and the lower portion 114b are fixed to the lifting table 105 side and cannot rotate, but the upper portion 114a can rotate around the reference line T1 independently of the die 5 and the lower portion 114b. When the upper portion 114a is rotated by an external driving force, the tilt direction of the die 5 and the lower portion 114b changes successively over 360° in the circumferential direction.

[0032] Note that the die 5 may be configured to move circumferentially in parallel along the XY plane, instead of being configured to have the axis C2 of the die 5 inclined eccentrically with respect to the reference line T1. With these configurations, the direction of deviation or inclination of the axis C2 can be changed so that it rotates around the reference line T1.

[0033] 5A and 5B, the die movable device 19 tilts the die 5 so that the axis C2 of the forming hole 6 in the die 5 (die axis) is inclined relative to the Z axis, and by swinging the die 5 in this state, it is possible to change (rotate) the direction of the inclination of the die axis C2. The inclination of the die axis C2 relative to the XY plane at the die exit point O is indicated by ε. When the die 5 is inclined relative to the material W located on the Z-axis, a difference occurs in the contact length between the material W and the die 5 at the die exit point O depending on the circumferential position of the material W. In response to this, by rotating the inclination direction of the die 5, the operation of rotating the oblique direction of the material W is repeated during the drawing process, so that the occurrence of bending of the drawn material based on the difference in the contact length between the material W and the die 5 can be actively utilized, and a drawn material that is close to straight can be obtained while suppressing the occurrence of macroscopic bending.

[0034] FIG. 6 shows an experimental apparatus 100 for confirming the effects of the drawing apparatus 1A of the first embodiment. The experimental apparatus 100 utilizes a driving device 101 used for tensile tests of materials, etc. The driving device 101 connects the upper ends of left and right side walls 102 with an upper wall 103, and connects the lower parts of the left and right side walls 102 with a fixed table 104. Above the fixed table 104, a lifting table 105 is disposed, which is supported by the left and right side walls 102 so as to be able to move up and down.

[0035] 7, an apparatus main body 110 is installed across the fixed table 104 and the lift table 105. In the experimental apparatus 100, the pulling direction of the material W (and the reference line T1) is oriented vertically. The device main body 110 includes a fixed side assembly 111 fixed to a fixed frame, and a lifting side assembly 113 fixed to the lifting table 105 .

[0036] The fixed-side assembly 111 is provided with a chuck 8 that grips a narrowed-mouth portion Wa (the lower end portion in the drawing) of the material W. With the lower end portion of the material W gripped by the chuck 8, a portion to be processed Wb extends upward and is inserted into the lifting-side assembly 113. The lifting side assembly 113 is equipped with a die 5 and an inlet guide device 11, and by this lifting side assembly 113 moving upward (away from the chuck 8) together with the lifting table 105, a situation is reproduced in which the chuck 8 relatively pulls out the material W downward from the die 5.

[0037] The lifting assembly 113 includes a die case 114 that houses the die 5, and a guide case 116 that is supported above the die case 114 via bearings 116a and houses the entry guide device 11. The die case 114 is fixed to the lifting table 105 via a fixing flange 115. The guide case 116 includes a plurality of handles 117 that extend radially in a top view, and a screw mechanism 118 that enables the radial position of the guide member 12 of the entry guide device 11 to be moved.

[0038] 8, the guide member 12 of the experimental apparatus 100 is a rectangular parallelepiped block having an insertion hole 12a through which the material W is inserted. The guide member 12 faces its longitudinal direction in a horizontal direction (radial direction) perpendicular to a reference line T1 along the vertical direction, and is housed in a die case 114 so as to be displaceable in the longitudinal direction. Tips of adjustment screws 118a fastened from the outer periphery of a guide case 116 in a screw mechanism 118 abut on both longitudinal sides of the guide member 12. The radial position of the guide member 12 can be adjusted with respect to the reference line T1 by adjusting the amount of fastening of the adjustment screws 118a on both longitudinal sides.

[0039] 10, the effect of "an eccentric device that displaces the axis C1 of the material W from the reference line T1 on the entry side of the die 5 and changes the direction of the displacement of the axis C1 along the circumferential direction around the reference line T1" in the second embodiment of the present invention will be described. Since the eccentric device is provided on the entry side of the die 5, the initial curvature (bending) of the material W can be eliminated. The relationship between the bending of the material W upstream of the die 5 in the conveying direction and the offset amount (eccentricity amount δ) of the inlet guide device 11 is obtained in the following preliminary experiment. In the preliminary experiment, the material W is drawn twice in the order of diameter "10 mm → 9.7 mm → 9.4 mm" without the inlet guide device 11. The curvature of the material W at this time is set as a target value, and the offset amount (eccentricity amount δ) of the inlet guide device 11 in the following main experiment is set. The preliminary experiment is performed using a material W without an initial bending. When this material W is drawn twice as described above, the occurrence of bending of the material W due to factors other than the initial bending is confirmed. The bending of the material W at this time is set as a target value for the main experiment, and the straightening effect by the offset of the inlet guide device 11 is confirmed.

[0040] In this experiment after the preliminary experiment, first, the entry guide device 11 is offset so that "δ = 2 mm", and a first drawing process is performed to give an initial curvature to the material W. In the first drawing process, the diameter of the material W is changed from "10 mm" to "9.7 mm". Next, in the second drawing process, the entry guide device 11 is offset in four ways, "δ = 0, 1, 2, 3 mm", and each drawing process is performed.

[0041] Referring to Fig. 9, in the second drawing process, the entry guide device 11 is rotated by 60° every time the material W is drawn out by 1 mm. As a result, the input to the material W due to the offset of the entry guide device 11 is equalized while switching by 60° in the circumferential direction of the material W. Therefore, even if the material W on the entry side has a curvature and is bent in one direction, the material W will not be drawn while contacting the die 5 while being bent in one direction with respect to the die axis C2, and the material W will be drawn while swinging to the opposite side of the initial bend. Therefore, it is possible to suppress the occurrence of macroscopic bending of the drawn material due to a difference in the contact length between the material W and the die 5.

[0042] The results of the above experiment are shown in the graph of FIG. 12. The vertical axis of the graph in FIG. 12 is the curvature (10 -5 mm -1 ), and the horizontal axis of the graph indicates the axial range in which the curvature of the blank W was measured. Line PL1 in the graph indicates the curvature (target value: Target) after the blank W without initial curvature was drawn twice in the preliminary experiment. In the preliminary experiment, the occurrence of bending of the material W due to factors other than the initial bending is confirmed. By setting the curvature PL1 of the material W without the initial bending in the preliminary experiment as the target value (Target) of the main experiment, it is considered that the smaller the deviation from the target value, the more the initial curvature (bending) of the material W can be eliminated. The curvature (Target) after the preliminary experiment in the embodiment is in the negative region. With reference to Fig. 10, a positive curvature indicates that the material W is bent to the left side in the figure with respect to the die axis C2, and a negative curvature indicates that the material W is bent to the right side in the figure with respect to the die axis C2.

[0043] Referring to Fig. 12, in the first drawing process of this experiment (eccentricity amount δ = 2 mm), the curvature of the material W after processing occurs in a positive region (line L1 in the figure: Before 2nd drawing). In the second drawing process of this experiment (eccentricity δ = 0 mm), the curvature of the processed material W occurs in a positive region, similar to the curvature after the first drawing process, but the curvature decreases overall (line L2 in the figure).

[0044] In the second drawing process of this experiment (eccentricity amount δ = 1, 2, 3 mm), the curvature of the processed material W changes to the negative region and generally approaches (converges) to the curvature after the preliminary experiment (lines L3, L4, L5 in the figure). In other words, by setting the offset amount of the inlet guide device 11 to about "eccentricity amount δ = 1, 2, 3 mm" and performing the drawing process while rotating the inlet guide device 11, it was confirmed that even when performing drawing using a material W with an initial bend, a drawn material with a curvature similar to that when a material W without an initial bend is used can be obtained.

[0045] As described above, the drawing apparatuses 1A, 1B, and 1C in each of the above embodiments are apparatuses that transport the raw material W along the conveying path 2, insert the raw material W into the forming hole 6 of the die 5 on the conveying path 2 from the upstream side, and pull the raw material W out to the downstream side of the forming hole 6 to form a specified outer peripheral shape. The conveying path 2 is equipped with eccentric devices (entrance guide device 11, exit guide device 13, die movable device 19) that shift or tilt the axis C1 of the raw material W into an eccentric state relative to a reference line T1 that overlaps with a straight imaginary axis, and the eccentric devices change the direction of the shift or tilt of the axis C1 along the circumferential direction centered on the reference line T1.

[0046] The drawing method in the above embodiment is a method in which the raw material W is transported along the conveying path 2, the raw material W is inserted from the upstream side into the forming hole 6 of the die 5 located halfway along the conveying path 2, and drawn out to the downstream side of the forming hole 6 to form a specified outer peripheral shape. The raw material W is drawn out on the conveying path 2 including the die 5 while performing an eccentric operation in which the axis C1 of the raw material W is shifted or tilted relative to a reference line T1 that overlaps with a straight imaginary axis, and a rotational operation in which the direction of the shift or tilt of the axis C1 is changed along the circumferential direction centered on the reference line T1.

[0047] According to this configuration, in the drawing processing apparatus 1A, 1B, 1C in which a long material W such as a bar, wire, or tube is conveyed along the conveying path 2 and drawn using the die 5 while reducing the diameter to produce a drawn material, the conveying path 2 including the die 5 is provided with an eccentric device for shifting or tilting the axis C1 of the material W, and the direction of the shift or tilt of the axis C1 is changed so that it rotates around the reference straight line T1, thereby further improving the straightness of the drawn material W. That is, even if the material W is bent or there is a shift or tilt with respect to the axis C2 of the die 5 in the drawing direction, the material W is intentionally eccentric at the inlet side or outlet side of the die 5 or at the die 5, and the following action and effect can be obtained. That is, by repeating the operation of rotating the oblique direction of the material W during the drawing process, the occurrence of bending of the drawn material based on the difference in the contact length between the material W and the die 5 is actively utilized, and the occurrence of macroscopic bending is suppressed to obtain a drawn material that is nearly straight. As a result, the process of straightening the drawn material can be simplified or omitted, and the drawn material can be produced efficiently.

[0048] The drawing processing apparatus 1A, 1B in the first and second embodiments is provided with an eccentric device on at least one of the entrance and exit sides of the die 5 on the conveying path 2, which shifts the axis C1 of the material W from a reference line T1 in an eccentric state and changes the direction of the shift of the axis C1 along the circumferential direction centered on the reference line T1, and a holding device 15, 17 which is positioned farther from the die 5 than the eccentric device and holds the material W on the reference line T1. According to this configuration, by rotating the misalignment of the axial center C1 of the raw material W around the reference straight line T1, it is possible to impart repeated bending and unbending deformation to the raw material W by the eccentric device. When the eccentric device is provided on the entry side of the die 5, the raw material W can be passed through the die 5 while the initial curvature (bending) of the raw material W disappears. This makes it possible to prevent the initial curvature of the raw material W from remaining in the drawn material. When the eccentric device is provided on the exit side of the die 5, even if a curvature (bending) is likely to occur in the drawn material due to the initial curvature (bending) of the raw material W or the misalignment or inclination of the die 5 with respect to the axial center C2 in the drawing direction, it is possible to prevent the curvature from remaining in the drawn material by repeatedly bending and unbending the drawn material directly on the exit side of the die 5. Furthermore, by providing the eccentric device and the holding device 15, 17 on at least one of the entry side and the exit side of the die 5, the material W whose free end side is restrained can be stably subjected to repeated bending and unbending deformation by the eccentric device. In other words, the eccentric device prevents the free end side of the material W from whirling when the eccentric device rotates the material W in the eccentric direction, and the material W can be stabilized and repeatedly bent back. Although the holding devices 15 and 17 contribute to stable unbending of the material W, it is possible to eliminate the holding devices 15 and 17 when the rotation in the eccentric direction is slow.

[0049] In the third embodiment, the drawing processing apparatus 1C has an eccentric device that tilts the axis C2 of the die 5 together with the axis C1 of the material W in an eccentric state relative to a reference line T1, and changes the direction of inclination of the axis C2 in the circumferential direction around the reference line T1. According to this configuration, the axis C2 of the die 5 through which the material W passes is inclined with respect to the reference line T1, and the inclination direction of the axis C2 of the die 5 is rotated around the reference line T1, so that the material W can be repeatedly bent and unbended. That is, even if the material W is bent or there is a deviation or inclination with respect to the axis C2 of the die 6 in the drawing direction, the die 5 intentionally generates eccentricity in the material W and changes the eccentricity direction so as to rotate, so that the occurrence of bending of the drawn material based on the difference in contact length between the material W and the die 5 is actively utilized, and the occurrence of macroscopic bending can be suppressed to obtain a drawn material that is nearly straight. As a result, the correction process of the drawn material can be simplified or omitted, and the drawn material can be efficiently manufactured.

[0050] The present invention can be widely used in industry to manufacture shafts and various parts of automobiles, paper feed shafts for printers, and components for precision instruments such as medical instruments. The configurations in the above-described embodiments are merely examples of the present invention, and various modifications are possible without departing from the gist of the present invention, such as replacing the components of the embodiments with well-known components. [Explanation of symbols]

[0051] 1A,1B,1C Drawing processing equipment 2. Transport Route 5 Dice C2 axis center 6 Molding hole 11 Inlet guide device (eccentric device) 13 Exit guide device (eccentric device) 15 Entry side holding device (holding device) 17 Output side holding device (holding device) 19 Dice Mobile T1 Reference Line W Material C1 axis center

Claims

1. A drawing apparatus for conveying a material along a conveying path, inserting the material from an upstream side into a forming hole of a die on the conveying path, and drawing the material to a downstream side of the forming hole to form a specified outer peripheral shape, comprising: The conveying path is provided with an eccentric device for shifting or tilting the axis of the material with respect to a reference line overlapping with a straight imaginary axis, The eccentric device is a drawing device that changes the direction of deviation or inclination of the shaft core along the circumferential direction centered on the reference straight line.

2. 2. The drawing apparatus according to claim 1, further comprising an eccentric device disposed on at least one of the entrance side and exit side of the die in the conveying path, the eccentric device displaces the axis of the material from the reference straight line and changes the direction of the deviation of the axis along a circumferential direction centered on the reference straight line.

3. At least one of the entrance side and the exit side of the die in the conveying path, the eccentric device that causes the axis of the material to be in an eccentric state by being shifted with respect to the reference straight line and changes the direction of the deviation of the axis along a circumferential direction centered on the reference straight line; 2. The drawing apparatus according to claim 1, further comprising a holding device that is disposed farther from the die than the eccentric device and that holds the material on a reference straight line.

4. The drawing apparatus according to claim 1, wherein the eccentric device tilts the axis of the die relative to the reference straight line in an eccentric state, and changes the direction of tilt of the axis along a circumferential direction centered on the reference straight line.

5. A drawing method for conveying a material along a conveying path, inserting the material from an upstream side into a forming hole of a die on the conveying path, and drawing the material to a downstream side of the forming hole to form a specified outer peripheral shape, comprising: The drawing method draws out the material while performing an eccentric operation in which the axis of the material is shifted or tilted eccentrically with respect to a reference line that overlaps with a straight imaginary axis on the conveying path including the die, and a rotation operation that changes the direction of the shift or tilt of the axis along a circumferential direction centered on the reference line.

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