JP2013022590A - Device and method for manufacturing inner tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an inner tube which is uniform and has small deviation in an outer diameter and a wall thickness even though heat treatment is applied.SOLUTION: A manufacturing device for the inner tube includes a support section 11 for supporting a tube C made of a metal material, and a press-fitting section 12 arranged opposite to the support section 11, wherein a spherical body D having an outer diameter larger than an inner diameter of the tube C and being harder than a material of the tube C is press-fitted to and passed through the tube C.

Description

  The present invention relates to an inner tube manufacturing apparatus and an inner tube manufacturing method for manufacturing an inner tube of a shock absorber used for a front fork or the like of a motorcycle, and more particularly to a method for correcting roundness.

  A shock absorber 100 is attached to the front fork of the motorcycle M (see FIG. 2). The shock absorber 100 is configured by combining an outer tube 110 and an inner tube 120. In the inner tube manufacturing method, a tube processed by core drawing from a raw tube is induction-quenched and tempered (furnace return / high-frequency). At this time, the tube is deformed and the roundness is lowered. The amount of deformation at this time is about 0.1 to 0.3 mm when the outer diameter is, for example, 50 mm. In order to correct this deformation, an outer diameter grinding step is performed in which the outer circumference is ground to adjust the outer diameter.

Japanese Patent No. 4647964 JP 59-130633 A JP 2007-061894 A

  The above-described inner tube manufacturing method has the following problems. That is, since the outer peripheral surface is ground, the outer diameter is constant, but the thickness after grinding is not uniform. In addition, a grinding allowance in anticipation of the deformation amount is required, and the outer diameter of the raw tube is increased, and at the same time, the grinding process (number of times of grinding) is increased. In addition, since scratches remain on the outer peripheral surface, the function as a shock absorber may be affected.

  Therefore, the present invention provides an inner tube manufacturing method and an inner tube manufacturing method in which the outer diameter and thickness are uniform and the outer peripheral surface is not scratched when the outer diameter and the wall thickness are uniform and the grinding allowance is not uniform. The purpose is to provide.

  In order to solve the problems and achieve the object, the inner tube manufacturing apparatus and the inner tube manufacturing method of the present invention are configured as follows.

  A support part that supports a tube made of a metal material, and a sphere made of a metal material that is disposed opposite to the support part, has an outer diameter larger than the inner diameter of the tube, and is harder than the material of the tube. -It has a press-fitting part that allows it to pass.

  A tube is formed by coreing the raw tube, the tube is heat-treated, and a metal sphere having an outer diameter larger than the inner diameter of the tube is press-fitted and passed through the tube.

  According to the present invention, it is possible to produce an inner tube that is uniform in both outer diameter and thickness, and that is not damaged on the outer peripheral surface, even if the tube has been heat-treated.

The side view which shows typically the inner tube manufacturing apparatus which concerns on one embodiment of this invention. The perspective view which shows typically the shock absorber apparatus with which the inner tube manufactured by the inner tube manufacturing apparatus was integrated. The graph which shows the internal diameter after an automatic correction before and after the ball sizing (press-fit process) of the inner tube manufactured with the inner tube manufacturing apparatus. The graph which shows the outer diameter before and after the ball sizing (press-fit process) of the inner tube manufactured by the inner tube manufacturing apparatus, and after automatic correction. The graph which shows the full length before and after the ball sizing (press-fit process) of the inner tube manufactured by the inner tube manufacturing apparatus, and after automatic correction. The graph which shows the runout (bending) before and after the ball sizing (press-fit process) of the inner tube manufactured by the inner tube manufacturing apparatus, and after automatic correction. The graph which shows the internal-diameter dimension and roundness after heat processing of the inner tube manufactured with the same inner tube manufacturing apparatus, and before ball | bowl sizing (press-fit process). The graph which shows the internal diameter dimension and roundness after ball sizing (press-fit process) of the inner tube manufactured with the inner tube manufacturing apparatus.

  FIG. 1 is a side view schematically showing an inner tube manufacturing apparatus 10 according to an embodiment of the present invention, and FIG. 2 shows a shock absorber apparatus 100 in which an inner tube 120 manufactured by the inner tube manufacturing apparatus 10 is incorporated. It is a perspective view showing typically. 3 to 6 are graphs showing measured values before and after ball sizing (press-fit processing) of the intertube 120 by the inner tube manufacturing apparatus 10 and after automatic correction.

  As shown in FIG. 1, the inner tube manufacturing apparatus 10 has a bottomed cylindrical support portion 11 that supports a metal tube C, and an outer diameter larger than the inner diameter of the tube C in the tube C. And a press-fitting portion 12 for press-fitting and passing a sphere D made of a metal material harder than the C material. The press-fit portion 12 includes a hydraulic cylinder 13 and a rod 14 that is operated by the hydraulic cylinder 13. A metal sphere D is detachably disposed at the tip of the rod 14. The spherical body D is formed of a metal harder than the material of the tube C and has an outer diameter slightly larger than the inner diameter of the tube C.

  FIG. 2 schematically shows a shock absorber 100 in which the inner tube 120 manufactured by the inner tube manufacturing apparatus 10 is used. That is, the shock absorber 100 is used for a front fork or the like of the motorcycle M, and the outer tube 110 and the inner tube 120 are arranged coaxially and configured to be slidable in the axial direction.

  The inner tube 120 is manufactured using the inner tube manufacturing apparatus 10 as follows. In addition, except the case where heat processing is performed, a process is advanced under normal temperature (10-40 degreeC). In the inner tube manufacturing method, the tube C is plastically processed by drawing the base tube. Next, a predetermined heat treatment such as induction hardening and tempering (furnace return / high frequency) is performed to form a metal structure. At this time, the tube is deformed and the roundness is lowered.

  Next, the tube C is inserted into the opening of the support portion 11 of the inner tube manufacturing apparatus 10, and the outer peripheral surface is fixed. Next, the sphere D is placed on the upper end of the tube C. Then, the hydraulic cylinder 13 is operated to extend the rod 14. Thereby, the sphere D is press-fitted into the tube C. The extension speed of the rod 14 is about 15 mm per second, for example. In this way, the sphere D is passed through the tube C to complete the process.

  Next, the shake (bend) of the tube C is corrected using an automatic bend straightening machine.

  Furthermore, grinding of the outer peripheral surface of the tube C, a flaw detection test, etc. are performed, and the inner tube 120 is completed.

  Here, it demonstrates based on the dimension of the concrete tube C and the inner tube 120, etc. FIG. For example, before heat treatment, a tube C having an axial length of 603 mm, an inner diameter of 45 mm, an outer diameter of 48.5 mm, and a wall thickness of 1.75 mm is used. Next, when heat treatment is performed, the inner diameter, outer diameter, total length, and runout change as shown in FIGS. Here, the runout is the amount of bending at the center measured on the basis of the outer diameter. I. R (Axial eccentricity: Total Indicator Reading).

  Next, using the inner tube manufacturing apparatus 10, a sphere D having a diameter of 48.5 mm is press-fitted into the tube C to correct the tube C, that is, perform ball sizing. After ball sizing, the inner diameter, outer diameter, total length, and runout change as shown in FIGS. That is, the inner and outer diameters are increased and the overall length is shortened. However, the same change does not occur with respect to runout, and it becomes larger or smaller. This is influenced by the initial bending amount after quenching.

  That is, the inner diameter, the outer diameter, and the total length are hardly changed, the variation in the inner diameter is eliminated, and the runout is reduced. Such a tendency is the same at both ends and the center of the tube C.

  FIG. 7 is a graph showing the inner diameter and roundness after heat treatment of the inner tube manufactured by the inner tube manufacturing apparatus 10 and before ball sizing (press fitting), and FIG. 8 is manufactured by the inner tube manufacturing apparatus 10. 6 is a graph showing the inner diameter size and roundness after ball sizing (press-fit processing) of the inner tube.

  In this way, the tube C is heat treated and then corrected using the sphere D, so that the outer diameter and the wall thickness are uniform, the roundness of the inner tube 120 is improved, and the tube C is incorporated in the shock absorber 100. However, desired performance can be obtained.

  Moreover, since the machining allowance of the outer peripheral surface can be minimized, it is possible to save materials.

  As described above, according to the inner tube manufacturing apparatus 10, even the heat-treated tube C is manufactured, the inner tube 120 having a uniform outer diameter and wall thickness and having no damage on the outer peripheral surface is manufactured. It becomes possible.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Inner tube manufacturing apparatus, 11 ... Support part, 12 ... Press-fit part, 13 ... Hydraulic cylinder, 14 ... Rod, C ... Tube, D ... Sphere.

Claims (2)

A support portion for supporting a tube made of a metal material;
A press-fit portion disposed opposite to the support portion and having a larger outer diameter than the inner diameter of the tube and press-fitting and passing a sphere made of a metal material harder than the tube material. Inner tube manufacturing equipment. Form the tube by centering the base tube,
Heat treating the tube,
A method of manufacturing an inner tube, comprising: pressing and passing a metal sphere having an outer diameter larger than the inner diameter of the tube into the tube.

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