JP3820551B2 - Feeding mechanism and processing apparatus provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a feed mechanism that drives a stroke of a machining unit when machining such as drilling or spot welding, and a machining apparatus including the feed mechanism.
[0002]
[Prior art]
Conventionally, when machining such as drilling or spot welding, a pneumatic or hydraulic feed mechanism has been used to drive the machining unit with a stroke. In recent years, those driven by an AC servo motor capable of accurately performing speed and position control from the conventional pneumatic or hydraulic type have come to be used.
[0003]
FIG. 3 shows a configuration example of a drilling device using an AC servomotor. In this drilling device, a drill unit 100 as a machining unit is reciprocated by a predetermined stroke along the axial direction of the ball screw 101 via a feed nut 102 screwed with the ball screw 101. The ball screw 101 is rotationally driven by an AC servo motor 103 at one end thereof.
[0004]
When used for drilling or spot welding, the full stroke of the drill unit 100 includes a rapid feed stroke (high speed region) and a machining stroke (low speed region). In a ball screw system or the like that mechanically transmits thrust, the feed speed is reduced by the machining stroke so as to prevent impact and noise between the workpiece and the like. For example, the rapid traverse stroke is about several mm to several tens mm, and the machining stroke is about several hundred mm. The faster the feed rate in the rapid traverse stroke, the shorter the machining time.
[0005]
Here, the relationship between the pitch P of the ball screw, the feed speed, and the machining thrust is expressed by the following equation.
Ball screw pitch P = Rapid feed speed / Maximum motor speed Motor torque (N · m) = Processing thrust (N) × Ball screw pitch P / 2π
[0006]
[Problems to be solved by the invention]
In a machining apparatus using an AC servo motor or the like, the feed speed can be increased by increasing the ball screw pitch as can be seen from the above relational expression, but it is necessary to increase the motor output to obtain machining thrust. is there. Therefore, there are problems such as an increase in the size of the apparatus or an increase in cost.
[0007]
In view of such circumstances, an object of the present invention is to provide a feed mechanism that can substantially reduce the size and cost of the apparatus while performing appropriate machining, and a machining apparatus including the feed mechanism.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a feed mechanism configured to feed and drive a machining unit supported so as to be capable of moving a stroke, wherein the machining unit and a drive unit for moving the stroke are provided with a pinion diameter. The two rack and pinion mechanisms are connected to each other, and the first rack and pinion mechanism is switched to the second rack and pinion mechanism at an appropriate place in the middle of the stroke of the machining unit.
[0009]
In the feed mechanism of the present invention, the pinion diameter of the first rack and pinion mechanism is larger than the pinion diameter of the second rack and pinion mechanism, and the second rack and pinion mechanism is moved from the first rack and pinion mechanism to the second rack It is preferable to switch to a pinion mechanism.
[0010]
In the feed mechanism of the present invention, the backlash of the pinion of the first rack and pinion mechanism is preferably set large.
[0011]
In the feed mechanism of the present invention, preferably, a relief is provided at the rack inlet end of the second rack and pinion mechanism.
[0012]
In the feeding mechanism of the present invention, a gap is preferably provided in the rack switching portion between the first rack and pinion mechanism and the second rack and pinion mechanism.
[0013]
Further, the present invention is a processing apparatus for performing predetermined processing on a workpiece while feeding and moving a processing unit supported so as to be movable in a stroke. This is characterized in that the machining thrust is increased at an appropriate position during the stroke.
[0014]
According to the present invention, the pinion diameter of the second rack and pinion mechanism is larger than the pinion diameter of the first rack and pinion mechanism, and the second rack and pinion from the first rack and pinion mechanism near the stroke end. Switch to mechanism. The machining unit can be fast-forwarded by the first rack and pinion mechanism, and can be fed with a large machining thrust by the second rack and pinion mechanism.
Thereby, in the rack switching part between the 1st rack and pinion mechanism and the 2nd rack and pinion mechanism, both can be connected smoothly and appropriately.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a feed mechanism according to the present invention and a processing apparatus including the same will be described with reference to the drawings.
FIG. 1 shows a configuration example of a processing apparatus 10 provided with a feed mechanism of the present invention. In this embodiment, the apparatus main body 11 includes, for example, a spot welding unit as the processing unit 12 and performs spot welding on the workpiece W. In this case, the electrode 14 of the spot welding unit is supported on the movable portion 13. The movable portion 13 is reciprocated in the X direction via the guide 15.
[0016]
The feed mechanism of the present invention is configured to feed and drive the processing unit 12 supported so as to be movable in the X direction. The machining unit 12 and the drive unit 3 for moving the stroke are connected via two sets of rack and pinion mechanisms 1 and 2 having different pinion diameters, and the first rack and pinion mechanism is placed at an appropriate position in the middle of the machining unit 12 stroke. The first rack and pinion mechanism 2 is switched from the first.
[0017]
The first rack and pinion mechanism 1 includes a rack 1a having a length corresponding to a fast-forward stroke supported and fixed to the movable portion 13 along the X direction, and a large-diameter pinion to which the output shaft 3a of the drive unit 3 is fixed. 1b. The drive unit 3 is composed of an AC servo motor. The second rack and pinion mechanism 2 includes a rack 2a having a length corresponding to the machining stroke supported and fixed to the movable portion 13 along the X direction, and a small-diameter pinion 2b to which the output shaft 3a of the drive unit 3 is fixed. Including.
[0018]
The rack 1a and the pinion 1b are finished with a general processing accuracy. The rack 2a and the pinion 2b are finished by general high-precision polishing. The specific diameters of the pinion 1b and the pinion 2b are appropriately set in consideration of the feed speed and the like.
[0019]
Here, as described above, in the present invention, two sets of rack and pinion mechanisms 1 and 2 having different pinion diameters are used to feed and drive the machining unit 12, but two kinds of pinions are used in this way. When doing so, a clutch is usually provided for each pinion so as to be switched. However, if such a clutch or the like is provided, the configuration of the apparatus becomes complicated and large as it is. Therefore, in the present invention, as will be described below, the rack switching unit 4 between the first rack and pinion mechanism 1 and the second rack and pinion mechanism 2 does not use an extra mechanism such as a clutch. Is configured to perform smoothly.
[0020]
That is, as shown in FIG. 2, for example, the backlash of the pinion 1a of the first rack and pinion mechanism 1 is set large.
Further, a relief is provided at the rack inlet end (part B in FIG. 2) of the second rack and pinion mechanism 2.
Further, a gap G is provided in the rack switching unit 4 between the first rack and pinion mechanism 1 and the second rack and pinion mechanism.
[0021]
In the above configuration, according to the present invention, when the machining unit 12 is fed and driven to perform spot welding by the machining apparatus 10, the machining unit 12 (electrode 14 side) is moved upward in FIG. In this case, the pinion diameter of the first rack and pinion mechanism 1 is larger than the pinion diameter of the second rack and pinion mechanism 2, and the rack switching unit 4 near the end of the stroke causes the first rack and pinion mechanism 1 to Switch to the second rack and pinion mechanism 2. Accordingly, the machining unit 12 can be fast-forwarded by the first rack and pinion mechanism 1 and can be fed by the second rack and pinion mechanism 2 with a large machining thrust.
[0022]
In this case, the rack switching section 4 between the first rack and pinion mechanism 1 and the second rack and pinion mechanism 2 smoothly connects the both without using an extra mechanism such as a clutch as described above. be able to. Therefore, while having a simple configuration, the operation cycle of the apparatus can be shortened and machining can be performed with an appropriate machining thrust.
[0023]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the present invention. For example, although it demonstrated in the example of spot welding, a drilling apparatus can be comprised by mounting a drill unit, and the effect similar to the said embodiment can be obtained.
[0024]
【The invention's effect】
As described above, according to the present invention, by suitably using two sets of rack and pinion mechanisms in this type of feeding mechanism, the motor of the drive unit can be substantially reduced in size, and A sufficiently large machining thrust can be obtained. This has the advantage that the device can be substantially reduced in size and cost.
[Brief description of the drawings]
FIGS. 1A and 1B are a plan view and a front view showing a configuration of a processing apparatus provided with a feed mechanism of the present invention. FIGS.
2 is an enlarged view of a part A in FIG. 1 showing a configuration example of a switching part of the rack and pinion mechanism according to the present invention.
FIG. 3 is a diagram illustrating a configuration example of a drilling device using a conventional AC servomotor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st rack and pinion mechanism 2 2nd rack and pinion mechanism 3 Drive unit 3a Output shaft 4 Rack switching part 10 Processing apparatus 11 Main body 12 Processing unit 13 Movable part

Claims (6)

A feed mechanism configured to feed and drive a machining unit supported so as to be movable in a stroke,
The machining unit and a drive unit for moving the stroke are connected via two sets of rack and pinion mechanisms having different pinion diameters, and the second rack and pinion mechanism is moved from the first rack and pinion mechanism to an appropriate position in the middle of the machining unit stroke. A feed mechanism characterized by switching to a rack and pinion mechanism. The pinion diameter of the first rack and pinion mechanism is larger than the pinion diameter of the second rack and pinion mechanism, and the first rack and pinion mechanism is switched to the second rack and pinion mechanism near the stroke end. The feeding mechanism according to claim 1, wherein: The feed mechanism according to claim 1 or 2, wherein a backlash of the pinion of the first rack and pinion mechanism is set large. The feed mechanism according to any one of claims 1 to 3, wherein a relief is provided at a rack inlet end of the second rack and pinion mechanism. The feed mechanism according to any one of claims 1 to 4, wherein a gap is provided in a rack switching portion between the first rack and pinion mechanism and the second rack and pinion mechanism. A processing apparatus for performing predetermined processing on a workpiece while feeding and moving a processing unit supported so as to be movable in a stroke,
A machining apparatus comprising the feed mechanism according to claim 1, wherein the machining thrust is increased at an appropriate position in the middle of a stroke of the machining unit.

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