JP2006035235A - Bending method for metal tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and surely form a small-diameter part, which is made eccentric, integrally by applying simple cold plastic working to a metallic tube material. <P>SOLUTION: A method for working a metal tube is used for forming a tapered part 10 and a small-diameter part 9 that is continuously and non-coaxially connected to the part 10 in a metallic tube raw material 7. A main body 8 and the small-diameter part 9 of the metallic tube raw material 7, in which the tapered part 10 and the small-diameter part 9 continuously connected to the part 10 are formed, are firmly held by grasping members 1, 2 respectively. The non-coaxial small-diameter part 9 is formed by relatively moving the grasping members 1, 2 in a direction non-perpendicular to the tube axis. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for bending a metal tube.

  Conventionally, there is a case where a tubular member integrally having a small-diameter portion eccentric with respect to an axis of a main body portion is required for a structural member of an automobile. As an example of a method for forming such a tubular member, a method in which a main body, a tapered portion (pressed product), and a small diameter portion are connected by welding is known. However, this forming method has a problem that the cost is increased and the strength and weight are inferior to those of an integrated product.

  In order to solve this problem, a method of integrally forming an eccentric tube from a developed plate material, a so-called U-O tube forming method has been proposed (see Patent Document 1).

  In addition, as a method of decentering and reducing the diameter of a single pipe, the main body and the small diameter portion of the pipe material that has been processed into a small diameter through the tapered portion are gripped on the main body, and the main body and the small diameter portion are gripped. Both clamps are moved at right angles to the tube axis (Y-Y direction in FIG. 4) and relatively in opposite directions to make an eccentric small diameter portion, and then the eccentric bending portion is moved in the tube axis direction. A method of forming a crank by compression has been proposed (see Patent Document 2).

Furthermore, one side of the tube material is firmly held by the first clamp, and the other side is gripped loosely (loosely) by the second clamp, in an oblique direction relative to the tube axis and relative to the tube axis. A construction method is disclosed in which both clamps are moved in the opposite direction to form an eccentric portion (see Patent Document 3).
Japanese Patent Publication No. 7-63758 JP 56-36353 A Japanese Patent No. 3000017

  Although the forming method of Patent Document 1 is satisfactory in terms of strength, the problem of cost cannot be solved because a large mold is required.

  Moreover, according to the formation method of the said patent document 2, possibility that a buckling will generate | occur | produce in the taper part of the short actual length side is very high. This will be described with reference to FIG. 4. Before the eccentric processing, the actual lengths of the anti-eccentric processing side tapered portion 11 and the eccentric processing side tapered portion 12 are both L1, as shown in FIG. 4A. . When both clamps move in the opposite directions on the Y axis and are eccentrically processed as shown in FIG. 4B, the anti-eccentric processing side taper portion 11 is changed from the actual length L1 to L2 to L4. Further, when the eccentric processing side taper portion 12 is positioned on the extension line of the main body portion 8 in the middle of the eccentric processing, the actual length L3 becomes L3 <L1, and is reduced and compressed by the length of L5. . Accordingly, since an extension force acts on the anti-eccentric processing side taper portion 11, even if there are few problems in processing, a compressive force acts on the eccentric processing side taper portion 12, resulting in a problem of buckling. There is.

  Therefore, in the construction method in which the clamp is moved in a direction perpendicular to and relatively opposite to the tube axis, the eccentric small diameter portion that can be formed has a very limited shape with a small amount of eccentricity, which is not practical.

  Furthermore, according to the formation method of Patent Document 3, the length of the eccentric portion can be formed without limit with respect to the main body. However, since the eccentric portion is not formed unless the diameter is the same, the above problem is solved. Must not.

  From the above, a technique capable of integrally forming the eccentric small-diameter portion by simple cold plastic working is desired, and further, it is more desirable if not only the eccentricity but also the relationship of inclination and twist can be formed.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to propose a method for bending a metal tube that can solve the above-described problems and meet the above-mentioned demands.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a method of processing a metal pipe in which a tapered portion and a non-coaxial small-diameter portion continuous with the tapered portion are formed in a metal pipe material, the tapered portion and The main body and the small-diameter portion of the tube material in which the continuous coaxial small-diameter portions are formed are firmly held by the gripping members, and both the gripping members are moved relative to the tube axis in a direction not perpendicular to the non-coaxial small-diameter portions. It is characterized by forming.

  In the present invention, the actual length of the taper portion on the eccentric processing side can be increased by moving both gripping members that hold the main body portion and the small-diameter portion of the intermediate material relative to the tube axis in a non-perpendicular direction. A non-coaxial small-diameter portion can be formed without shortening, that is, without applying a compressive force.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, a mandrel is inserted into at least one of the main body portion and the small diameter portion, and the mandrel is moved in synchronization with the gripping member. is there.

  In the present invention, the deformation of the cross section of the portion other than the tapered portion can be prevented by the restriction to the tube material from the inside by the mandrel.

  According to the first aspect of the present invention, by performing a simple cold plastic working on the tube material, it is possible to reliably integrally form the small diameter portion eccentric to the main body portion without causing buckling of the tapered portion. .

  Moreover, not only a simple eccentric (parallel) shape but also an eccentric shape with inclination or twist can be formed.

  According to the invention of claim 2, by inserting the mandrel, it is possible to prevent the flow to the inside of the pipe part other than the taper part and to form a more accurate shape.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described based on an embodiment shown in the drawings.
The tube material 7 which is an intermediate material processed according to the present invention, that is, the metal tube before being processed according to the present invention is composed of a large diameter portion 8, a taper portion 10 and a small diameter portion 9 which are main body portions. The shaft is common (coaxial) and formed integrally.

  The tube material 7 which is the intermediate material is pressed from the axial direction of the tube material 7 with a die having a taper surface to a large diameter tube which is a main body portion by a die pressure welding method or the like in the pre-process of the process of the present invention. By forming the taper portion 10 and the small diameter portion 9 in the tube material 7, the tube material 7 in which the large diameter portion 8, the small diameter portion 9, and the taper portion 10 are integrated and coaxial as shown in FIG. Is forming. Further, although STKM11A is used as the material of the tube material 7, it is not limited to this material, and other materials may be used as long as it is a metal tube.

  In this embodiment, the diameter of the large diameter portion 8 is φ54, the small diameter portion is φ37, and the plate thickness is t1.4.

  A processing apparatus for processing the tube material 7 according to the present invention is shown in FIG. 5 as a first clamp 1 which is a gripping member for gripping the large-diameter portion 8 of the tube material 7 from the outside. The second clamp 2 is a gripping member that grips the small-diameter portion 9 of the tube material 7 from the outside, and both the clamps are split.

  In FIG. 5, one mold 1 a of the first clamp 1 has a semicircular groove 16 a formed along the axial direction of the tube material 7 so that the large diameter portion 8 of the tube material 7 can be gripped by a semicircle. Yes. The groove 16b is also formed symmetrically in the other mold 1b. The two molds 1a and 1b are brought into contact with each other so that the semicircular grooves 16a and 16b are combined, so that a gripping hole 4 penetrating in the axial direction of the tube material 7 is formed and the large-diameter portion 8 is firmly gripped. It has become.

  Similarly, the second clamp 2 is also formed as shown in FIG. 6, and a semicircular groove 17a is formed in one mold 2a and the other mold 2b so that the tube material 7 can be gripped by a semicircle. , 17b are formed along the axial direction of the tube material, and the two molds hold the 2a, 2b so that the semicircular grooves 17a, 17b are joined together and penetrate the tube material 7 in the axial direction. A hole 5 is formed to firmly grip the small diameter portion 9.

  Therefore, the tube material 7 is gripped by the first clamp 1 and the second clamp 2 in a state of being inserted across the gripping holes 4 and 5.

  The sliding surfaces 1c and 2c in contact with each other of the first clamp 1 and the second clamp 2 are orthogonal to the same axis XX as the tube axis, as shown in FIGS. It is formed in a plane inclined by a predetermined angle α with respect to the surface Z in one direction. Both sliding surfaces 1c and 2c are inclined in the same direction. The predetermined angle α is set to 7.3 degrees in the embodiment. Both the clamps 1 and 2 can slide in directions opposite to each other along the sliding surfaces 1c and 2c.

  Further, on the sliding surface 1c side of the first clamp 1, a gap 6 opened to the sliding surface 1c is provided in a predetermined amount toward the gripping hole 4 and from the shaft core portion to the eccentric side of the tube. The tube is prevented from interfering with the first clamp 1 due to the presence of the gap 6 when the tube is deformed in the eccentric processing of the tube.

  The second clamp 2 is driven by a driving means (not shown) in FIG. 1 with sliding surfaces 1c and 2c (in FIG. 1 to FIG. 3, the sliding surface made up of the sliding surfaces 1c and 2c is denoted by reference numeral 3). ) To move up and down. The first clamp 1 may be moved up and down along the sliding surfaces 1c and 2c in FIG. 1 by driving means (not shown).

Next, the eccentric processing step from the tube material will be described.
First, the 1st clamp 1 and the 2nd clamp 2 are arrange | positioned in the position where the holding holes 4 and 5 (tube axis) become coaxial, and each split mold is maintained in the state which left | separated right and left. 1A, the large diameter portion 8 of the tube material 7 is inserted between the split molds of the first clamp 1, and the small diameter of the tube material 7 is inserted between the split molds of the second clamp 2. The portion 9 is inserted, the taper portion 10 of the tube material 7 is inserted into the gap 6 in the first clamp 1, and the split molds are closed by driving means (not shown), as shown in FIG. The outer peripheral surface of the large-diameter portion 8 of the tube material 7 is firmly held by both grooves 16a and 16b in both molds 1a and 1b of the first clamp 1, and the outer peripheral surface of the small-diameter portion 9 of the tube material 7 is second The clamps 2 are firmly held by both grooves 17a and 17b in both molds 2a and 2b. Both clamps 1 and 2 are in contact with sliding surfaces 1c and 2c.

  Next, as shown in FIG. 1B, the second clamp 2 that holds the small-diameter portion 9 is slightly slid along the sliding surfaces 1c and 2c in the B direction by a driving means (not shown). As a result, the small-diameter portion 9 is pulled in a state where the tube axis is maintained horizontally from the state shown in FIG. 1 (a) obliquely downward to the right (non-perpendicular to the tube axis B) while being firmly held. At this time, the anti-eccentric processing side taper portion 11 of the taper portion 10 is plastically deformed and extended by a force pulling the small diameter portion 9 diagonally downward to the right. Further, as shown in FIG. 4B, the taper portion 10 of the taper portion 10 has a tip portion Q1 that moves obliquely downward to the right about the base portion P, and the tip portion Q1 is as described above. Move from the Y-axis to the small diameter portion 9 side. At this time, as described above, the second clamp 2 moves in the direction opposite to the first clamp 1 to allow the movement of the tip portion Q1, and the eccentric processing side tapered portion 12 maintains the actual length. , Or stretched by being pulled by a small amount and plastically deformed downward without being compressed.

  As a result, the small-diameter portion 9 is translated in the diagonally downward direction to the right, and the tube axis is decentered by OF1. The reason why the translation is performed is that the sliding surface 3 is a flat surface.

  Next, as shown in FIG. 1C, a larger parallel movement is performed by the same operation as the above-described step. Thereby, the eccentricity OF2 is obtained. By this operation, the eccentric processing side taper portion 12 is deformed to a state where it is substantially flush with the eccentric side portion 13 of the large diameter portion 8 and the eccentric side portion 14 of the small diameter portion 9. At this time, the tip portion Q1 of the eccentric processing side taper portion 12 is deformed with the actual length L1 and becomes the position of Q2 shown in FIG. 4B, and moves from the Y axis to the small diameter portion 9 side by the amount of L5. . This movement for L5 is allowed by the movement of the second clamp 2 in the opposite direction to the first clamp 1 as described above, and the eccentric processing side taper portion 12 is actually realized without generating a compression force. The length L1 is maintained to become the actual length L6 (L1 = L6), and the eccentric processing side tapered portion 12 does not buckle.

  Further, as shown in FIG. 1 (d), the sliding is advanced by the same operation as the above-described process to decenter to OF3. In this state, the eccentric processing side taper portion 12 of the taper portion 10 can be inclined downward without interfering with the first clamp 1 by the gap 6 provided on the lower side of the taper portion 10, and the large diameter portion 8 can be deviated. The eccentric side portion (lower surface) 14 of the small diameter portion 9 can be positioned below the core side portion (lower surface) 13. As a result, a state in which the movement width C (see FIG. 4B) protrudes from the outer peripheral surface of the large diameter portion 8 is obtained. In this way, a metal tube having a large eccentricity OF3 can be formed.

  Moreover, when taking out the metal tube after shaping | molding, it can take out easily by separating apart the split type of the 1st clamp 1 and the 2nd clamp 2 which are holding the metal tube firmly. The inclination angle α of the sliding surfaces 1c and 2c of the clamps 1 and 2 is set so that the relationship between L1 and L6 is L1 = L6 as described above or L1 <L6.

  In the series of steps described above, the eccentric processing side taper portion 12 of the taper portion 10 can be deformed without buckling. As described above, the second clamp 2 is inclined rightward in the direction opposite to the first clamp 1. By translating in the downward direction, the distance between the longest part P and Q2 (L6) is always longer than or equal to the distance between the shortest part P and Q1 (L1) of the tapered portion 10 (= not shortened). This is because bending is performed while maintaining the relationship. Moreover, the anti-eccentricity processing side taper part 11 is always extended by a tensile force. For this reason, it is performed smoothly by the plastic flow only extending in the taper part 10 in a process, and it is rare to cause buckling or fracture. The ratio (elongation rate) between the length of L1 and the length of L6 is preferably about several to 10%.

  FIG. 2 shows the second embodiment. In the first embodiment, the mandrel 18 is inserted into the large diameter portion 8 side, and the mandrel 19 is inserted into the small diameter portion 9 side. This is an example in which the cross-sectional deformation of the portion 9 is prevented.

  As shown in FIG. 2A, the mandrel 18 and the mandrel 19 are inserted from the opening end of the large diameter portion 8 of the tube material 7 when the tube material 7 is inserted into the first clamp 1 and the second clamp 2. The mandrel 18 is inserted into the inside of the tube, and inserted and held up to a position where the mandrel 18 is bent from the large diameter portion 8 to the tapered portion 10. Similarly, on the small diameter portion 9 side, the mandrel 19 is inserted and held from the opening end of the small diameter portion 9 to a position where the mandrel 19 is bent from the small diameter portion 9 to the tapered portion 10. In this state, an operation similar to that in the processing step is performed to form an eccentric tube. At this time, the mandrel 19 is also moved in synchronism with the moving clamp, in the illustrated embodiment, the second clamp 2.

  By the restriction from the inside by the mandrel 18 and the mandrel 19, the (cross-sectional) shapes of the large-diameter portion 8 and the small-diameter portion 9 are accurately determined even during eccentric processing. However, since the material flow (supply) to the maximum extension portion indicated by reference numerals 20 and Q2 shown in FIG. 4 (b) where the maximum extension is required deteriorates, care must be taken not to cause breakage of this portion.

  When the mandrel 18 is not inserted, the shape of the bent portion 20 from the large-diameter portion 8 to the tapered portion 10 is a large curved surface. If there is no problem as a product function, this shape is more suitable for the mandrel. Since there is no material, machining is simple and there is little risk of breakage. The shape of the processed part Q2 is also the same.

  As described above, the mandrels 18 and 19 may be used for both the large diameter portion 8 and the small diameter portion 9 as shown in FIG. 2, or may be used for one of the small diameter portions 9 as shown in FIG. One of the large-diameter portions 8 may be used, or neither of them may be used.

Next, an application example of the above embodiment will be described with reference to FIG.
FIG. 7 shows an application example to instrument panel reinforcement, which is a structural member of an automobile.

  As described in Japanese Examined Patent Publication No. 7-63758, this part is usually configured to have a large diameter only on the side of the driver's seat to which the steering is attached, and the other parts are integrally formed by a small diameter pipe material.

  When the pipe material is configured integrally with the large-diameter portion 30 and the small-diameter portion 31 as in this application example, and the shaft centers of the large-diameter portion 30 and the small-diameter portion 31 are eccentric, FIG. As described above, the small-diameter portion 31 is preferably eccentric from the large-diameter portion 30 via the tapered portion 32 of the pipe material. Then, the counterpart part is fitted and welded to the small diameter part 31.

  The bending method of the present invention is suitable for manufacturing instrument panel reinforcement in which the small-diameter portion 31 is eccentric through the tapered portion 32.

Further, the present invention may be applied to manufacture of automobile exhaust system parts.
For example, the bending method of the present invention is suitable for manufacturing a part in which both ends of a long tubular member are eccentric with a small diameter, such as the muffler case described in FIG. 1 of JP-A-2003-314240.

  FIG. 8 shows a sliding surface 41c of the first clamp 41, which is a gripping member, is a concave primary surface on the first clamp 41 side in Example 3, and the sliding of the second clamp 42, which is a gripping member. This is an example in which the surface 42c is a primary curved surface convex toward the first clamp 41 side. Further, the arc centers 01 of the sliding surfaces 41c and 42c are provided eccentrically by a distance L7 on the side opposite to the eccentricity processing side from the axis X of the large diameter portion 8 of the tube material 7. Further, the first clamp 41 is formed with a gap 46 similar to the gap 6, and the second clamp 42 is also formed with a gap 47 around the holding hole 43. FIG. 8 shows a state at the end of the machining process. Other structures of the tube material 7 and the clamps 41 and 42 are the same as in the above embodiment.

  In the machining step, the second clamp 42 slides on the curved sliding surfaces 41c and 42c downward from the drawing from the state where the large diameter portion 8 and the small diameter portion 9 are coaxial as shown in FIG. While rotating counterclockwise counterclockwise, the small diameter portion 9 is eccentric and inclined as shown in FIG. In other words, the second clamp 42 slides on the curved sliding surfaces 41c and 42c, so that the center of rotation is located on the right side of the second clamp 42 and above the axis X of the tube material 7. In the state, the second clamp 42 rotates downward. As a result, the gripping hole 43 formed in the second clamp 42 tilts toward the opposite side of the first clamp 41, that is, diagonally downward to the left in FIG. At this time, the axis of the gripping hole 43 is also eccentric downward.

  The small-diameter portion 9 gripped by the gripping hole 43 is deformed as the gripping hole 43 is moved, and has a shape inclined upward by D with respect to the tube axis while being offset downward (non-parallel).

  Also in this embodiment, since the rotation center 01 of the second clamp 42 is eccentric by L7, the eccentric processing side taper portion 12 in the tube material 7 maintains the same length as in the first embodiment. Or it is pulled and deformed, and its buckling and breaking are prevented.

  In FIG. 9, the sliding surface 51c of the first clamp 51, which is a gripping member, is a primary curved surface convex toward the second clamp 52, and the sliding surface 52c of the second clamp 52, which is a gripping member, is This is an example in which a concave surface is formed on the second clamp 52 side. Further, the arc centers 02 of the sliding surfaces 51c and 52c are provided eccentrically by a distance L8 on the eccentric processing side from the axis X of the large diameter portion 8 of the tube material 7. The first clamp 51 is formed with a gap 56 similar to the gap 6, and the second clamp 52 is also formed with a gap 57 around the holding hole 5. Other structures of the tube material 7 and the clamps 51 and 52 are the same as in the above embodiment. FIG. 9 shows a state at the end of the machining process.

  In the processing step, the second clamp 52 slides on the curved sliding surfaces 51c and 52c downward from the drawing from the state where the large diameter portion 8 and the small diameter portion 9 are coaxial as shown in FIG. While rotating clockwise, the small diameter portion 9 is eccentric and inclined as shown in FIG. That is, the second clamp 52 slides on the curved sliding surfaces 51 c and 52 c, so that the center of rotation is positioned on the left side of the first clamp 51 and below the axis X of the tube material 7. In this state, the second clamp 52 rotates downward. As a result, the gripping hole 53 formed in the second clamp 52 is inclined toward the opposite side of the first clamp 51, that is, diagonally downward to the right in FIG. At this time, the axis of the gripping hole 53 is also eccentric downward.

  The small-diameter portion 9 gripped in the grip hole 53 is deformed as the grip hole 53 moves and is offset downward (non-parallel) and has a shape inclined to the right by E with respect to the tube axis.

  Also in this embodiment, since the rotation center 02 of the second clamp 52 is eccentric by L8, the eccentric processing side taper portion 12 in the tube material 7 maintains the same length as in the first embodiment. Or it is pulled and deformed, and its buckling and breaking are prevented.

  In both the third and fourth embodiments, it is important to lay out so that the shortest actual length taper portion does not extend.

Further, although not shown in the drawings, as the fifth embodiment, the sliding surfaces 41c, 42c, 51c, 52c are formed as secondary curved surfaces, and the second clamps 42, 52 are driven to drive the primary curved surface side and the secondary curved surface side. May be provided.
That is, the sliding surfaces 41c, 42c, 51c, and 52c of both clamps are formed so that the second clamps 42 and 52 can rotate on the paper surface and also in a direction perpendicular to the paper surface in FIGS. Alternatively, by sliding in two directions in this way, it is possible to form an eccentric tube having a twisted relationship in which the large-diameter tube shaft and the small-diameter tube shaft are not on the same plane.

  Although the illustration of the clamp and the manufacturing process of the fifth embodiment is omitted, according to the fifth embodiment, for example, a tubular member comprising a large diameter portion 8, a tapered portion 10 and a small diameter portion 9 having a twist as shown in FIG. Can be obtained.

  In the third embodiment, the fourth embodiment, and the fifth embodiment, a mandrel may be inserted to prevent cross-sectional deformation of the large diameter portion and the small diameter portion in the processing process.

  In addition, the present invention can be applied as long as the metal pipe material is eccentric, and is applicable not only to automobile components and exhaust system members but also to processing of all metal tubular objects.

(A)-(b) is a longitudinal cross-sectional view which shows the process of the bending method of Example 1 of this invention. (A)-(b) is a longitudinal cross-sectional view which shows the process of Example 2 which inserted the mandrel in the large diameter part and the small diameter part in the process of FIG. (A)-(b) is a longitudinal cross-sectional view which shows the process of the state which inserted the mandrel only in the small diameter part in the process of FIG. The longitudinal cross-sectional view which showed the deformation | transformation process of the taper part of the workpiece in the Example of this invention. The large diameter part side clamp in the Example of this invention is shown, (a) is a side view, (b) is a top view, (c) is a front view. The clamp of the small diameter part in the Example of this invention is shown, (a) is a side view, (b) is a top view, (c) is a front view. The example of the process target of this invention is shown, (a) is a top view, (b) is a side view (c) is a front view. The longitudinal cross-sectional view of the clamp which shows Example 3 of this invention. The longitudinal cross-sectional view of the clamp which shows Example 3 of this invention. The articles | goods manufactured by Example 5 of this invention are shown, (a) is a side view, (b) is a front view.

Explanation of symbols

1, 2, 41, 42, 51, 52 Clamp (gripping member)
7 Tube material 8 Large diameter part (main part)
9 Small diameter part 10 Taper part 18, 19 Mandrel

Claims (2)

  A metal tube processing method for forming a tapered portion and a non-coaxial small-diameter portion continuous with the tapered portion in a metal tube material, the main body portion and the small-diameter of the tube material in which the tapered portion and the coaxial small-diameter portion continuous therewith are formed. A method of bending a metal tube, characterized in that each portion is firmly held by a gripping member, and both gripping members are moved relative to the tube axis in a non-perpendicular direction to form a non-coaxial small diameter portion.   The metal pipe bending method according to claim 1, wherein a mandrel is inserted into at least one of the main body part and the small diameter part, and the mandrel is moved in synchronization with the gripping member.

Images