JP5182803B2 - Tube material for front fork outer tube excellent in shock absorption and manufacturing method thereof - Google Patents

Description

  The present invention relates to a tube material for a front fork outer tube excellent in shock absorption and a manufacturing method thereof.

  There are two types of motorcycle front forks, upright and inverted, and aluminum alloy wrought material is used for the inverted outer tube. As for the material, Al-Zn-Mg alloy is usually used for off-road vehicles such as motocross vehicles, and Al-Mg-Si alloy is used for on-road vehicles. Yes.

  These front fork outer tubes require a larger inner diameter than the sliding portion with the inner pipe for sealing with the inner pipe at the lower end. For this reason, a necessary shape may be provided in advance by cutting from a pipe having a large wall thickness, but pipe expansion is often performed at the end of the pipe for cost reduction. (See Patent Document 1)

  In the case of an inverted front fork outer tube for on-road use, an Al-Mg-Si alloy T6 tempered tube or T8 tempered tube is used. In general, the shape of the pipe end is given by cutting.

However, the front fork outer tube manufactured by such a process has a problem that the toughness (impact characteristic) in the tube expansion processed portion is lower than that in the non-expanded tube processed portion, and the improvement thereof is desired.
JP 2007-119853 A

  In order to solve the above-described conventional problems, the present invention provides a process for casting, homogenization, hot extrusion, and pipe expansion in the manufacture of an Al-Mg-Si aluminum alloy front fork outer tube. It was made as a result of repeated tests and examinations on the relationship between the toughness (impact characteristics) of the welded part and the unexpanded processed part, and its purpose was excellent in shock absorption and the toughness of the expanded part was not expanded An object of the present invention is to provide a front fork outer tube tube material that is superior in toughness and a method for manufacturing the same.

  In order to achieve the above object, the pipe material for a front fork outer tube excellent in shock absorption according to claim 1 is composed of an Al-Mg-Si aluminum alloy tube whose end is expanded, and the aluminum alloy tube On the other hand, when a Charpy impact test without a notch is performed, E0 <E1 where E1 is the impact value of the expanded pipe portion and E0 is the impact value of the unexpanded portion.

According to a second aspect of the present invention, in the pipe material for a front fork outer tube having excellent shock absorption, the aluminum alloy pipe is made of JIS A 6061 alloy in the first aspect.

  A method for producing a pipe material for a front fork outer tube having excellent shock absorption according to claim 3 is a method for producing a pipe material for a front fork outer tube according to claim 1 or 2, wherein the Al-Mg-Si based aluminum is used. After casting the alloy, the resulting ingot is homogenized, hot extruded, solution treated, and quenched to produce a T4 tempered aluminum alloy tube, and after expanding the end of the aluminum alloy tube, It is characterized by performing artificial aging treatment.

A method for producing a pipe material for a front fork outer tube excellent in shock absorption according to claim 4 is a method for producing a pipe material for a front fork outer tube according to claim 1 or 2, wherein the Al-Mg-Si based aluminum is used. The alloy is cast, and the resulting ingot is homogenized, hot extruded, solution treated, quenched, drawn to produce a T3 tempered aluminum alloy tube, and the end of the aluminum alloy tube is expanded Then, artificial aging treatment is performed.

  According to the present invention, since the toughness of the pipe expansion processed part is superior to the toughness of the non-expanded processed part, a front fork outer tube pipe material excellent in shock absorption can be obtained.

  The tube material for a front fork outer tube excellent in shock absorption according to the present invention is composed of an Al-Mg-Si-based aluminum alloy tube whose end is expanded, and the aluminum alloy tube is subjected to a Charpy impact test without a notch. In this case, E0 <E1 where E0 <E1 where E0 is the impact value of the unexpanded processed portion that is not expanded, and E1 is the impact value of the expanded pipe end (expanded processed portion), and E0 <E1 As a result, excellent shock absorption can be imparted to the front fork outer tube.

  The shape of the test piece of the notch-free Charpy impact test is not particularly limited because the shape that can be formed varies depending on the diameter and thickness of the tube expansion portion and the non-expansion tube processing portion. For example, a test of 2.5 mm × 10 mm × 55 mm A piece is used. The Charpy impact test is performed at room temperature in accordance with JIS Z 2242 “Metal material impact test method”.

The tube material for the front fork outer tube of the present invention is made of an Al—Mg—Si based aluminum alloy, and among the Al—Mg—Si based aluminum alloys, it is a JIS A 6061 alloy from the balance of strength, toughness and corrosion resistance. More preferably.

  Hereinafter, the manufacturing method of the pipe material for front fork outer tubes excellent in shock absorption of the present invention is explained. First, an Al-Mg-Si-based aluminum alloy is cast by a technique such as semi-continuous casting, and the resulting ingot is homogenized, hot-extruded, solution-treated, and quenched in accordance with a conventional method. An aluminum alloy tube is produced. You may perform the process of a softening process and a drawing process suitably between a hot extrusion and solution treatment.

  Next, after expanding the end portion of the T4 tempered aluminum alloy tube, an artificial aging treatment is performed. Although the pipe expansion processing method of an edge part is not specifically limited, For example, the method of pushing a plug inside a pipe | tube is used suitably. The tube expansion process may be performed at room temperature, but may be performed at a temperature of 300 ° C. or less. The artificial aging treatment condition after the pipe expansion process is not particularly limited because the optimum condition varies depending on the required strength, but as an example, a condition of 8 hours at a temperature of 175 ° C. is recommended.

As described above, Al-Mg-Si-based aluminum alloy is cast by a technique such as semi-continuous casting, and the resulting ingot is homogenized, hot-extruded, solution-treated, quenched, according to a conventional method , After drawing this to T3 tempering and expanding the end of the T3 tempered aluminum alloy tube, an artificial aging treatment may be performed. Also in this case, the above-mentioned tube expansion processing conditions and artificial aging treatment conditions can be applied.

  Conventionally, the pipe expansion process for the front fork outer tube was normally performed on the T6 tempered material or the T8 tempered material. However, in the present invention, the T4 tempered material or the T3 tempered material is used. Tube expansion is performed, and then an artificial aging treatment is performed, whereby the ductility is improved as the dislocation density is reduced due to recovery, and the characteristics of E0 <E1 can be obtained.

  Examples of the present invention will be described below in comparison with comparative examples. In addition, these Examples show one Embodiment of this invention, and this invention is not limited to these.

Example 1 and Comparative Example 1
An aluminum alloy having the chemical components shown in Table 1 was melted, an ingot having a diameter of 260 mm was produced by a semi-continuous casting method according to a conventional method, cut to a length of 1000 mm, then cut to an outer diameter of 254 mm, A through-hole was drilled by cutting to produce a tubular billet.

  The obtained billet was charged into an atmospheric furnace, heated to 520 ° C., and kept at this temperature for 10 hours for homogenization treatment and naturally cooled to room temperature. Then, it inserted in the induction heating furnace, heated up to 400 degreeC, and extruded by the indirect extrusion method which uses a mandrel to the pipe material of 55 mm of outer diameters, and 42 mm of inner diameters.

  The extruded tube material was subjected to a solution treatment at 540 ° C. for 1 hour using an atmospheric furnace, and then quenched into normal temperature tap water to obtain a T4 tempered material, which was cut into a length of 450 mm, and test material 1 It was.

  Moreover, the test material 2 made into T6 tempering was also produced by performing artificial aging treatment for 8 hours at 175 degreeC to said T4 tempered material.

  About the test material 1 and the test material 2, the pipe expansion process was performed by pushing the plug of diameter 65mm into a pipe end at normal temperature. The length of the pipe expansion processing part was 70 mm. After the pipe expansion process, the test material 1 was subjected to an artificial aging treatment at 175 ° C. for 8 hours, and the test material 2 was not subjected to the artificial aging treatment.

  About the test material 1 and the test material 2 after a process, while taking the tensile test piece and the Charpy impact test piece on the conditions shown below from the pipe expansion process part and the non-expansion process part, respectively, the tensile test and the Charpy impact test were done. . The test results are shown in Table 2.

  Tensile test: A tensile test piece having a parallel part diameter of 4 mm and a gauge distance of 10 mm is formed so that the tensile test direction coincides with the extrusion direction, and a tensile test is performed at room temperature in accordance with JIS Z 2241. 0.2% proof stress and elongation were measured.

  Charpy impact test: An unnotched Charpy impact test piece having a thickness of 2.5 mm, a width of 10 mm, and a length of 55 mm was molded, and a Charpy impact test was performed at room temperature in accordance with JIS Z 2242 to measure the impact value. At this time, sampling of the test piece in the pipe expansion processing part and the non-expansion processing part may be performed from any position of the pipe expansion processing part and the non-expansion processing part. Moreover, the impact test was performed by giving an impact with a hammer to a surface having a thickness of 2.5 mm and a length of 55 mm.

  As can be seen from Table 2, the test material 1 according to the present invention had a large elongation at the tube expansion processed portion, and the characteristics of E0 <E1 were obtained. On the other hand, T6 tempering before pipe expansion, and the test material 2 according to the conventional method in which the artificial aging treatment was not performed after pipe expansion, the elongation of the pipe expansion processed portion and the Charpy impact value were small, and E0> E1.

Example 2 and Comparative Example 2
The tubular billet having a through-hole having an outer diameter of 254 mm and an inner diameter of 48 mm produced in Example 1 was charged into an atmospheric furnace, heated to 520 ° C., and held at this temperature for 10 hours, as in Example 1. The mixture was then homogenized and naturally cooled to room temperature. Then, it inserted in the induction heating furnace, heated up at 400 degreeC, and extruded by the indirect extrusion method which uses a mandrel to 62 mm of outer diameters and 48 mm in inner diameter.

  The extruded tube material is subjected to a solution treatment at 540 ° C. for 1 hour using an atmospheric furnace, quenched into tap water, and further drawn to an outer diameter of 55 mm and an inner diameter of 42 mm to obtain a T3 tempered material. The test material 3 was cut into a length of 450 mm.

  Moreover, the test material 4 made into T8 tempering was also produced by performing artificial aging treatment for 8 hours at 175 degreeC to said T3 tempered material.

  About the test material 3 and the test material 4, the pipe expansion process was performed by pushing the plug of diameter 65mm into a pipe end at normal temperature. The length of the pipe expansion processing part was 70 mm. After the pipe expansion process, the test material 3 was subjected to artificial aging treatment at 175 ° C. for 8 hours, and the test material 4 was not subjected to artificial aging treatment.

  A tensile test and a Charpy impact test were performed under the same conditions as in Example 1 for the tube expansion portion and the non-expansion tube processed portion of the treated test material 3 and test material 4. The test results are shown in Table 3.

  As can be seen in Table 3, the test material 3 according to the present invention had a large elongation at the tube expansion portion, and the characteristics of E0 <E1 were obtained. On the other hand, the test material 4 according to the conventional method, which was subjected to T8 tempering before the pipe expansion and was not subjected to the artificial aging treatment after the pipe expansion, had a small expansion and Charpy impact value at E0> E1.

Claims (4)

When the end portion is made of an Al-Mg-Si-based aluminum alloy pipe whose pipe has been expanded, and when a Charpy impact test without a notch is performed on the aluminum alloy pipe, the impact value of the pipe-expanded portion is E1, A tube material for a front fork outer tube excellent in shock absorption, wherein E0 <E1 when the impact value is E0. The said aluminum alloy pipe | tube consists of a JISA6061 alloy, The pipe material for front fork outer tubes excellent in the shock absorption property of Claim 1 characterized by the above-mentioned. A method for producing a tube material for a front fork outer tube according to claim 1 or 2, wherein an Al-Mg-Si based aluminum alloy is cast, and the obtained ingot is homogenized, hot extruded, and solutionized. For a front fork outer tube with excellent shock absorption, which is manufactured and hardened to produce a T4 tempered aluminum alloy tube, the end of the aluminum alloy tube is expanded, and then an artificial aging treatment is performed. Manufacturing method of pipe material. A method for producing a tube material for a front fork outer tube according to claim 1 or 2, wherein an Al-Mg-Si based aluminum alloy is cast, and the obtained ingot is homogenized, hot extruded, and solutionized. A front fork with excellent shock absorption, characterized in that a T3 tempered aluminum alloy tube is produced by treatment, quenching and drawing, and the end of the aluminum alloy tube is expanded and then subjected to artificial aging treatment Manufacturing method of outer tube material.