KR100375702B1 - Method for manufacturing of seamless tube for vehicle alloy wheel - Google Patents

Abstract

The present invention is an automotive alloy comprising a rim portion 16 forming the uneven portion 14 from the edge portion 10 to the drop center portion 12 and the disc portion 18 coupled to the inside of the rim portion 16. It provides a method for manufacturing a seamless tube used in the rim portion for manufacturing a wheel. The present invention is to forge a rim material to obtain a cup-shaped preform 28, the step of fixing the preform 28 to the mandrel 32 to rotate, and the mandrel 32 to obtain a seamless tube 20 The rolling roller 38 is pressurized in the axial direction of the mandrel 32 in the radial direction with respect to the preform 28 by using three rolling rollers 38 which are arranged at intervals of 120 ° but not on the same concentric circle. And the rolling roller 38 moves forward with respect to the mandrel 32 along the longitudinal direction at an appropriate speed so as to perform flow molding so that the thickness decreases at the same time and continuously on the entire main surface of the preform 28.

Description

Manufacturing method of seamless tube for automobile alloy wheel {METHOD FOR MANUFACTURING OF SEAMLESS TUBE FOR VEHICLE ALLOY WHEEL}

The present invention relates to a method for manufacturing a seamless tube for manufacturing an automotive alloy wheel, in particular, in an automotive alloy wheel consisting of a rim portion and a disk portion coupled to the inside of the rim portion, the seamless used for forming the rim portion It relates to a method for producing a tube.

Typically, alloy wheels for automobiles are required to have high rigidity and light weight so that a material of aluminum or aluminum alloy is used and it is required to have a densified structure throughout the entire rim. In this respect, the rim (or drum) is an important part in the manufacture of alloy wheels for automobiles.

In manufacturing the rim portion of the conventional alloy wheel, for example, there is a method of molten forging the entire rim and the disk, and there is a continuous forging method for forging the disc-shaped material step by step. However, the molten metal forging method requires a molten metal forging machine with a complicated structure, and it is difficult to determine the thickness of the rim to the extent that the work process can obtain complicated defects, required rigidity and light weight. In addition, in the continuous forging method for forging the disk-shaped material step by step, waste of the raw material is large in the process of obtaining the disk-shaped material, and the process of forging such disk-shaped material to the tubular rim is too complicated.

In particular, in the case of manufacturing aluminum tubes for rim parts of automotive alloy wheels, the front and rear extrusion method is generally used, but large presses are used for the production of large tubes having an outer diameter of 400 to 700 mm and a thickness of 3.5 to 4.5 mm. In itself, the production costs are high and economic efficiency is low. In addition to the forward and backward extrusion method, there is also a method of producing by drawing a plate deep drawing, but the price of plate is high and the loss of material is also low, which is also economical. Meanwhile, there is also a method of arc welding by rolling a plate in a cylindrical shape, but in such a case, there is a problem of a decrease in strength due to defects in the welded part and a problem of air leakage after completion of the alloy wheel for automobiles.

In the present invention, the invention was made in view of such a conventional situation, and in order to provide an alloy alloy wheel for automobiles in which the number of processes is significantly shortened and the manufacturing mechanism contributing to the process is simple and the productivity and yield are significantly increased compared to other methods. Its purpose is to make seamless rims of alloy wheels for automobiles by manufacturing seamless tubes that have high thickness and high quality with the optimum thickness on the rims.

The present invention provides a method of manufacturing a seamless tube used in the rim portion for manufacturing an automotive alloy wheel consisting of a rim portion forming an uneven portion from the edge portion to the drop center portion and a disk portion coupled to the inside of the rim portion. do. The present invention is forging a rim material to obtain a cup-shaped preform, the step of fixing the preform to the mandrel and rotating, and 120 degrees spaced around the mandrel to obtain a seamless tube, but not placed on the same concentric circle Using three rolling rollers, the rolling roller is pressed in the axial direction of the mandrel in the radial direction with respect to the preform, and the rolling roller advances along the longitudinal direction at an appropriate speed with respect to the mandrel, simultaneously and continuously on the entire main surface of the preform. Flow forming to achieve a reduction.

Referring to the present invention in more detail based on the accompanying drawings as follows.

1 is a manufacturing process diagram of the invention and the alloy wheel for automobile using the same.

2 is a cross-sectional view of an alloy wheel for an automobile manufactured using a seamless tube manufactured according to the present invention.

3 is an explanatory diagram showing a process in which an alloy wheel for an automobile is manufactured using a seamless tube manufactured according to the present invention;

4 is an explanatory view showing a manufacturing process of a preform for obtaining a seamless tube of the present invention.

5 is an explanatory diagram of a flow forming process of obtaining a seamless tube by flow molding from a preform;

6 and 7 are explanatory views showing a molding process of a rim formed by using the seamless tube of the present invention.

<Code Description of Main Parts of Drawing>

16 ... Rim 18 ... Disc

20 ... Seamless tube 21 ... Unit tube

21 '... preformed unit tube 26 ... forged press

28 ... preform 30 ... flow molding machine

38 ... rolling roller 40 ... roll forming machine

48 ... 1st roller 50 ... 2nd roller

As shown in FIG. 2, an automotive alloy wheel includes a rim portion 16 that forms an uneven portion 14 from an edge portion 10 to a drop center portion 12, and a disc portion coupled to the inside of the rim portion 16. 18). In order to manufacture the alloy wheels for automobiles, first, a rim portion 16 is manufactured, and a disk portion 18 separately manufactured on the rim portion 16 is welded.

The production of the rim portion 16 is made through a process of manufacturing a seamless tube as a material to be used for the rim portion 16 and a rim forming process of rolling the tube in the shape of the rim portion 16.

The present invention relates to a method for producing a flow forming tube for an automotive alloy wheel. The manufacture of flow molded tubes for alloy wheels is to obtain a seamless tube 20 (FIG. 3B) as a material to be used for the rim 16.

The seamless tube 20 is a continuous cast billet is cut in a circular saw machine and heated to a forging temperature in a low-frequency induction heating furnace so that the heating material is a uniform forging temperature in a soaking furnace. The heated material is forged in a forging press 26 (FIG. 4) composed of a forging die 22 and a punch 24. Lubricate the forging die 22 and the punch 24, load the heated material into the forging die 22, control the hydraulic pressure of the forging press 26 to the appropriate pressure, offset forging first, and then finish forging second. Thus, a preform 28, which is a cup-shaped forged product as shown in Fig. 3A, is obtained.

The preform 28 produced by the forging process is then flows to precisely processed to a dimension suitable for manufacturing a seamless tube 20 having a thickness of 3.5 to 4.5mm with an optimum diameter for forming the rim portion 16 Perform molding processing. Flow molding machine 30 for this is shown in FIG.

The flow molding machine 30 for flow molding the seamless tube 20 has a mandrel 32 to which the preform 28 is coupled, and a tailstock coupled to the mandrel 32 to center the mandrel 32. (34), the spindle 35, the ejector ring 36 for ejecting the molded seamless tube 20 from the mandrel 32 and the mandrel for rolling to longitudinally flow the preform 28 in the longitudinal direction. It consists of three rolling rollers 38 (only two are shown in FIG. 5) which are arranged at intervals of 120 DEG around the 32 but are not placed on the same concentric circles. In the flow molding machine 30 of FIG. 5, the seamless tube 20 is almost completed.

The mandrel 32 to which the preform 28 to which the flow-forming lubricant is applied has been previously fixed is rotated, and each rolling roller 38 is pressed against the preform 28 in the axial direction of the mandrel 32 in the radial direction. As the rolling roller 38 is advanced along the longitudinal direction with respect to the mandrel 32, the flow molding is performed in which the thickness reduction is simultaneously and continuously performed on the entire main surface of the preform 28. As such, the process of flow molding the seamless tube 20 is an economical method because the work can be completed in a single process using three rollers to work three times using one roller to reduce the conventional cross section. something to do.

As a result of the seamless molding process of the seamless tube, it is applied to the production of two-piece rim, which is a lightweight model of automobile alloy wheels, while maintaining high strength and high quality while dramatically reducing the cost compared to conventional forged alloy wheels. To produce seamless tubes.

In particular, since the inner diameter of the seamless tube 20 is determined by the outer diameter of the mandrel 32 of the flow molding machine 30, when manufacturing the seamless tube of the same inner diameter, the thickness is changed only by adjusting the position of the rolling roller 38. Can be prepared.

The seamless tube manufactured by flow molding has excellent grain strength and elongation, which is excellent in tensile strength and elongation, which are mechanical properties after heat treatment (AA6061-T6 material, tensile strength 32kgf / mm2, elongation 12% or more) ). The seamless tube 20 manufactured according to the present invention has a dimensional accuracy of an inner diameter and an outer diameter, which is manufactured within a range of equipment tolerances and roller tolerances, so that the precision of the seamless tube 20 may be higher than that of other construction methods applied to the manufacture of large tubes having a diameter of 400 to 700 mm. It has excellent precision and has a precision of 0.05 ~ 0.1mm with respect to the outer diameter.

The seamless tube manufactured as described above may be rim formed by the following rim forming process. Of course, the following description of the rim forming process is only one example, and the rim may be formed by a process different from the following description.

The seamless tube obtained in the manufacturing process of the seamless tube is cut to a unit length suitable for forming the rim portion 16 and then molded in a roll forming machine (roll forming M / C). Such a roll forming machine 40 is shown in FIGS. 6 and 7.

The roll forming machine 40 includes a mandrel 44 forming a shape of a rim portion 16 fixed to the spindle 42, a tailstock 46, and a primary roller for rolling the rim portion 16. 48 and the secondary roller 50. As shown in FIG. The primary roller 48 moves only in the radial direction of the material to be molded, and the secondary roller 50 moves in the radial direction and the longitudinal direction.

As mentioned above, the seamless tube 20 is cut into unit lengths suitable for shaping the rim 16 (FIG. 3B). The cut unit tube 21 is inserted and coupled to the mandrel 44 forming the shape of the rim portion 16 fixed to the spindle 42 of the roll forming machine 40 and fixed in position by the tailstock 46. do. In this state, the spindle 42 rotates and the primary roller 48 advances in the radial direction of the unit tube 21 to preform the unit tube 21 to be close to the shape of the final rim portion 16. The unit tube 21 'is obtained. The reason for preforming the preforming unit tube 21 ′ using the primary roller 48 as described above is to move the primary roller 48 in the radial direction of the material to form the same shape as that of the rim. This is because when the processing exceeds a predetermined deformation amount of the material, the material may break or internal defects may occur. The primary roller 48 is to move in the radial direction of the material to pre-form the tubular material in the shape of the rim at one time to form a smooth curve of the molded part to uniformly distribute the processing amount during molding.

Thus, after preforming the preforming unit tube 21 'by using the primary roller 48, the primary roller 48 is retracted and the secondary roller 50 is advanced in the radial direction of the material. As described above, the secondary roller 50 is movable in the radial direction and the longitudinal direction with respect to the material so that the preformed unit tube 21 'having a gentle curved outline is dropped from the edge portion 10 to the drop center portion. It is to be molded into the rim portion 16 forming the uneven portion 14 up to (12).

As described above, the present invention provides a method of manufacturing a seamless tube for manufacturing an automotive alloy wheel, in which the number of processes is significantly shortened and the manufacturing mechanism contributing to the process is not only simple, but also the productivity and yield are significantly increased compared to other methods. By using the fluidity of the metal structure of the material, it is possible to manufacture a seamless tube having an optimal thickness on the rim and maintaining high strength and high quality. In addition, according to the method of manufacturing a seamless tube for manufacturing an alloy alloy wheel according to the present invention, since the continuous cast billet is used as the starting base material, it is possible to drastically reduce the occurrence of scrap compared to the method of using the base plate or disc-shaped material as the starting base material. Not only that, but there are also advantages in terms of purchasing cost of the base material.

Claims (2)

Manufactures an alloy alloy wheel for an automobile consisting of a rim portion 16 forming an uneven portion 14 from the edge portion 10 to a drop center portion 12 and a disc portion 18 coupled to the inside of the rim portion 16. In the manufacturing method of the seamless tube to be used for the rim portion, forging the rim material to obtain a cup-shaped preform 28, the step of fixing the preform 28 to the mandrel 32, and In order to obtain the seamless tube 20, the rolling roller 38 is connected to the preform 28 using three rolling rollers 38 which are arranged at 120 ° intervals around the mandrel 32 but are not placed on the same concentric circle. Pressurized in the axial direction of the mandrel 32 in the radial direction with respect to the mandrel 32 simultaneously and continuously on the entire circumferential surface of the preform 28 by advancing along the longitudinal direction at a set speed. Flow molding to reduce the thickness The method of manufacture of automotive alloy wheels seam less tubes characterized in that province. 2. The automobile according to claim 1, wherein the step of obtaining the cup-shaped preform 28 by forging the rim material is to cut and heat the continuously cast billet to a uniform forging temperature to finish the forging secondly after the first offset forging. Method for manufacturing seamless tube for alloy wheel manufacturing.