JP2004268167A - Machining device for light alloy wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machining device for a light alloy wheel for accurately machining a valve hole without causing external appearance failure even in the light alloy wheel narrow between spokes. <P>SOLUTION: This machining device for the light alloy wheel has the cutting function for machining the valve hole and the fixing function for fixing the light alloy wheel. The machining device has the detecting function for detecting a turning angle of the fixed light alloy wheel, and is characterized in that the fixing function has a gripping means for gripping the light alloy wheel, and a means for axially rotating the gripped light alloy wheel. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a machining apparatus for machining a valve hole, which is particularly useful for manufacturing a light alloy wheel having a large number of spokes such as a fin type or a mesh type.
[0002]
[Prior art]
There are various types of road wheels of automobiles made of various materials and structures, but with the aim of reducing the weight of automobiles and improving appearance and design, the proportion of light alloy wheels such as aluminum wheels is increasing. I have. This light alloy wheel is often manufactured by a low pressure casting method or a gravity casting method. In these casting methods, since the molten metal is filled into the mold cavity at a low speed, entrainment of gas and generation of oxides are suppressed as much as possible compared to other casting methods, so that safety is high. This is because an excellent shape can be obtained.
[0003]
Generally, as shown in FIG. 4, a light alloy wheel 30 includes a thick hub portion 31 attached to an axle by bolts and nuts, and a disk portion 32 including spokes 33 having a design in which a thick portion and a thin portion are mixed. And a thin rim portion 34 to which a tire is attached. An outer flange 35 and an inner flange 36 with which the tire abuts are formed at the end of the rim. Further, a valve hole 39 for adjusting the internal pressure of the tire is formed so as to penetrate from the periphery of the disk surface to the outer peripheral surface of the rim.
[0004]
When the above-mentioned wheel is manufactured and processed by a casting method, for example, it is manufactured from the following steps. First, a wheel material is cast by casting. Thereafter, the wheel material is subjected to a heat treatment such as a T6 treatment. As shown in FIG. 5 (a), the heat-treated vehicle wheel material is firstly held and fixed with an outer flange by a clamp. To cut the inner and outer peripheral surfaces on the inner flange side. When fixing the wheel to this lathe machine, it is natural that the center axis of the wheel coincides with the rotation axis of the lathe processing.
[0005]
Next, the vehicle wheel is carried to the machining device by the carrying means. Unlike a lathe shown in FIG. 5 (a), the machining device always forms a valve hole at a fixed location rather than aligning the center axis of the wheel with the rotation axis of the lathe. Therefore, the circumferential rotation angle is important. Is seen. For example, as a means for detecting the rotation angle, there is a means for reading and detecting the shape of the disk unit on the conveyor by an image processing device or the like. Further, as another means, there is a means in which a concave portion or a convex portion is formed at a predetermined position of an outer flange portion of a vehicle wheel material, and the portion is detected and captured by an infrared sensor, image processing, or the like. As a result, the vehicle wheel whose rotation angle is detected is fixed to a machining device as shown in FIG. 5B at a constant rotation angle by a robot arm or the like, and a hub hole, a bolt hole, and a valve hole are machined.
Thereafter, the inner flange side having the final shape as shown in FIG. 5C is held and fixed by a clamp, and the wheel material on the outer flange side is turned. At this time, the spoke surface and the disk surface of the hub are processed as necessary.
[0006]
For example, Japanese Patent Application Laid-Open No. 9-66407 and other known documents also describe a wheel chuck device for performing lathing on a wheel, and studies for improving the dimensional accuracy of the rim are being made well.
[0007]
[Patent Document 1]
JP-A-9-66407 (FIG. 1)
[0008]
[Problems to be solved by the invention]
However, although the dimensional accuracy of the rim as described above has been studied in the past, the dimensional accuracy of the valve hole of the wheel has not been improved at all. Even if a means for detecting the rotation angle is used in the wheel transfer line as described above, the degree of accuracy is ultimately determined by how accurately the wheel is mounted on the bolt hole machining device. Even if it is attempted to fix it to the machining device with a robot arm or the like, slight deviation cannot be suppressed. In the case of a wheel for a vehicle such as a spoke type or a dish type having a large gap between spokes, even if the position of the valve hole is slightly shifted, it cannot be visually recognized and there is no problem in design. However, the spoke spacing is extremely narrow, and in the case of a large-diameter vehicle wheel, the machining position of the valve hole is deviated by 1 mm or more just by shifting the machining attachment angle of the wheel by 0.2 °. In particular, as shown in FIG. 2, when the outer peripheral end 38 of the spoke extends beyond the valve hole position 39, the position of the valve hole is only 1 mm in the circumferential direction, and when it is severe, there is only a displacement of 0.3 mm. In this case, the appearance was poor, and the yield was deteriorated. Accordingly, an object of the present invention is to provide a machining apparatus for a light alloy wheel for accurately machining a valve hole, which does not cause a poor appearance even with a light alloy wheel having a narrow gap between spokes.
[0009]
[Means for Solving the Problems]
In order to improve the displacement of the valve hole in the circumferential direction, the present inventors provided a means for detecting the rotation angle of the vehicle wheel and a means for rotating the vehicle wheel on the machining device itself. An object of the present invention is to provide a machining device that can be applied to demands for advanced and highly designed products. That is, the present invention relates to a machining apparatus for a light alloy wheel having a cutting function having a cutting tool for machining a valve hole and a fixing function for fixing a light alloy wheel, and the light machine fixed to the machining apparatus. A detection function for detecting the rotation angle of the alloy wheel is provided, and the fixing function includes a gripping means for gripping the light alloy wheel, and a rotation function for rotating the gripped light alloy wheel about an axis. It is characterized by the following.
[0010]
Preferably, the rotation function is controllable within 0.2 °, more preferably within 0.1 °. Within this range, even a large-diameter (16 inch or more) vehicle wheel can be suppressed within 1 mm, and further, within 0.5 mm or less. The detailed driving mechanism and control mechanism for rotating the shaft will be described in Examples.
[0011]
It is preferable that the detection function is performed based on spokes on the disk surface formed on the light alloy wheel. The reference portion may be, for example, a side edge of the spoke portion and may be detected by an optical sensor or the like. The output data of the detected position is fed back to a rotation function of an NC rotary table or the like, and is rotated by a predetermined angle within an error range of 0.2 degrees or less, preferably 0.1 degrees or less, and a method of processing a valve hole can be adopted. As described above, the approximate rotation angle can be detected and controlled before being attached to the machining device by the robot arm or the like. Therefore, it is preferable that the angle control of about 10 ° or more be separately managed before mounting on the machining device, and the more detailed angle control be controlled by the rotation function after the vehicle wheel is mounted on the machining device.
[0012]
Although the processing steps are shown in the prior art, the processing steps are not particularly limited. However, when the position of the spoke is detected by a sensor and the angle is controlled, it is preferable to apply the machining device of the present invention after processing the spoke side. For example, unless the back side of the design surface is processed as shown in FIG. 4A, it is difficult to perform detailed position detection because burrs formed by casting remain on the side surfaces of the spokes. Even if another part is used as a reference for position detection, it is preferable that the reference part is a processed part that has been processed once after casting.
[0013]
The effect of the present invention can be similarly obtained not only in the valve hole but also in the bolt hole. In addition, the present technology can be used in applications such as processing a design surface portion of a spoke into a predetermined shape or engraving a mark having a design.
[0014]
It is useful to apply a vehicle wheel to one made of a light alloy. Generally, an aluminum alloy using AC4CH or the like is mainly used. However, it is needless to say that a casting wheel or a forging wheel made of an Mg alloy, and an aluminum wheel formed by die casting using ADC3, ADC5, ADC12, or the like can be applied. is there.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
First, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view of a fixing function of a vehicle wheel which is a main part of the present invention. This fixing function includes a support 6 for fixing to a substrate and a support column 7 fixed to the support 6. A rotary shaft 5 is provided horizontally from the support column 7, and the rotary table 2 is installed on the rotary shaft 5. Further, the turntable 2 is provided with a window 4 for receiving light for position detection and gripping means 3a, 3b, 3c for fixing the vehicle wheel to the turntable 2. Reference numeral 8 denotes a cutting oil supply port.
[0016]
The turntable 2 is a table portion of an NC rotary table controlled by NC. The main body (not shown) of the NC rotary table is fixed to a support column 7. The main body of the NC rotary table is provided with a servomotor for rotating the table, and an encoder for position detection for controlling the rotation. Further, gripping means 3a, 3b, 3c for gripping the vehicle wheel are provided on the table side, so that the inner flange can be pressed and fixed to the table.
[0017]
A method of controlling the position of the wheel will be described with reference to FIG. First, the image processing device reads the spoke shape on the disk surface of the vehicle wheel material that has flowed from the previous process by the belt conveyor, and determines in which direction the vehicle wheel material has flowed. Based on the determination result, the vehicle wheel material is rotated by a required angle by a rotary drive device (not shown) on the line, and is conveyed while being arranged in a certain direction with respect to the flowing direction of the line. Thereafter, the vehicle wheel is taken out of the transfer line by the robot arm, and the inner flange of the vehicle wheel material is pressed against the turntable 2 so that the portion where the valve hole is formed is on the lower side. In this state, the gripping means 3a, b, and c operate, and the vehicle wheel material is fixed to the machining device. By this operation, the portion where the valve hole is formed is mounted with an error of about 10 ° or less with respect to the angle from the optimum position (position to be drilled by the drill cutting tool) axis.
[0018]
The rotation angle is detected with respect to the mounted vehicle wheel material. A light beam from an optical sensor (not shown) is applied to the position 4 in FIG. This optical sensor mainly comprises a light beam transmitter, a light detector, and a reflecting mirror. When the irradiated light hits the back side (cast surface) of a predetermined spoke, it is irregularly reflected. When the irradiated light does not hit the spokes, the light passes through between the spokes and hits a reflecting plate (not shown) on the front side of the paper of FIG. 1 so that the light is almost reflected. ing.
When the wheel is rotated by the turntable, the reflectance of light changes depending on whether or not there is a spoke at the position where light is irradiated. The reflected light is arranged in a uniform parallel direction via the light receiving lens. The irregularly reflected light has a weak amplitude and diffuses into the light receiving lens, so that the light reflected through the light receiving lens has a large area and a small amplitude. When light does not hit the spokes, the incident light becomes reflected light while being substantially condensed, and becomes light having a small area and a large amplitude. The reflected light is picked up by a half mirror that transmits light from the incident side, and read by a photodetector.
When the position where the light is irradiated moves from the back of the spoke to a single surface by rotating the wheel, the value read by the photodetector changes rapidly. The position detecting device sends a signal to the turntable 2 based on the read change of the photodetector, stops the rotation at a predetermined rotation angle, and fixes the wheel. After that, the position detecting device sends a signal to the drilling machine to perform drilling of the valve hole.
[0019]
FIG. 2 shows a pattern in which a valve hole is formed in the wheel (the hatched portion is a space). In the figure, 35 is an outer flange, and 39 is a valve hole. Thus, the valve hole is formed in the middle between the spokes 33 without any deviation. Reference numeral 33a controls the rotation angle by light irradiation at this position, which is the end of the spoke side surface. In a conventional valve hole machining apparatus having no rotation angle control, even if the rotation angle of the wheel is shifted by 0.2 degrees, the hub hole is shifted by about 1 mm, and the distance between the spokes as shown in FIG. Within 30 mm, the appearance was poor even with a deviation of 0.5 mm. According to the present invention, appearance defects are eliminated, and the difference between the center position between the spokes and the center position of the valve hole does not deviate within a maximum of 0.5 mm and an average of 0.2 mm or less. Has been secured.
[0020]
When performing strict angle control within 0.2 degrees, the back surface of the spoke, which is a casting surface, is processed to improve the dimensional accuracy of the spoke end surface. In many cases, the spoke end surface is a portion where the upper mold and the lower mold come into contact with each other during casting, and if burrs or the like are generated, accurate position control cannot be performed even if the above-described position control method is used. Control was difficult with a rotation angle of 2 degrees. It has also been found that it is important that the measurement position of the wheel for performing position control for controlling the rotation angle be at least 30 degrees from the position of the valve hole. This is because the processing of the valve hole is performed after the heat treatment of the wheel, and the heat treatment may cause the entire disk surface to be distorted. Therefore, unless the position is controlled based on a position as close to the valve hole as possible, the drill processing position and the cutting position may not match each other even if the reading by the sensor is correct. In particular, the tendency is noticeable in a large-diameter wheel of 16 inches or more.
[0021]
【The invention's effect】
As described above, according to the present invention, a machining apparatus for a light alloy wheel having an unconventional structure can be provided. By using this, it is possible to form a valve hole with almost zero angle deviation, improve the yield without causing poor appearance even with a narrow wheel with a spoke distance of less than 30 mm, and establish a good production state Was completed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a machining apparatus for a light alloy wheel according to the present invention.
FIG. 2 is a schematic diagram showing positions of spokes and valve holes of a wheel.
FIG. 3 is a schematic diagram for explaining angle control.
FIG. 4 is a sectional view of a vehicle wheel.
FIG. 5 is a view showing a processing step of a conventional vehicle wheel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Machining device, 2 turntable, 3 gripping means, 4 windows, 5 rotating shafts, 6 support stand, 7 support pillar, 30 vehicle wheel, 31 hub part, 32 disk part, 33 spoke, 34 rim part, 35 outer flange , 36 Inner flange, 39 Valve hole

Claims (3)

A machining device for a light alloy wheel having a cutting function for machining a valve hole and a fixing function for fixing a light alloy wheel,
The machining device is provided with a detection function for detecting the rotation angle of the fixed light alloy wheel,
The fixing device further includes a gripper for gripping the light alloy wheel, and a unit for rotating the gripped light alloy wheel around an axis. The machining apparatus for a light alloy wheel according to claim 1, wherein the means for rotating the light alloy wheel about an axis is controllable at an angle of 0.2 ° or less. The machining device for a light alloy wheel according to claim 1 or 2, wherein the detection function detects a rotation angle based on spokes on a disk surface formed on the light alloy wheel.

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