JP3042715U - Belt break detector - Google Patents

Abstract

(57) [Abstract] [Purpose] Do not install a counterweight or balance cylinder suitable for the spindle device in the machine tool that moves the feed screw shaft (gravitational force direction moving shaft) that moves the spindle device in the vertical direction via a belt. Prevents the spindle device from falling due to a belt break. [Structure] A photoelectric switch that divides a belt that drives a feed screw shaft that moves a spindle device in the vertical direction into a plurality of parts, irradiates each belt with light from a projector, and detects the reflected light by a light receiving element is provided. Provide one of them
A belt breakage detection device configured to stop the machine quickly by operating a photoelectric switch that cannot receive reflected light when the book belt is cut.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to a safety device for a working machine in which a feed screw shaft for moving a main shaft device in a vertical direction is driven by a belt.

[0002]

[Prior art]

 Conventionally, assuming that the drive motor that drives the feed screw shaft that moves the spindle device in the vertical direction loses the braking force for some reason, it is fixed to the nut that is screwed to the feed screw shaft and is fixed in the vertical direction. Even if the braking force of the drive motor is released by applying the force of the balance cylinder, which is commensurate with the weight of the moving spindle, in the direction opposite to that acting by the mass of the spindle, the spindle moves on the feed screw shaft. It was thought that it would not move suddenly.

[0003]

[Problems to be solved by the device]

 In the conventional method mentioned above, the speed of the machining center cannot be increased if a hydraulic cylinder with a piston speed of 300 mm / sec is used as an upper limit for high-speed feed specifications such as more than 24 m / min as in recent machining centers. As a result, machine tools are being developed to eliminate the balance cylinder and accelerate the speed.In this case, the braking force of the drive motor will not be transmitted to the feed screw shaft due to belt exhaustion, and the spindle device may fall. You have been exposed.

An object of the present invention is to realize a high speed machine tool safely and easily at low cost by a belt breakage detecting device which solves the above problems.

[0005]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, a belt width having a transmission force sufficient to drive the feed screw shaft for vertical movement is obtained, and the belt width is divided into two to irradiate each belt with the light of the projector of the distance setting type photocell switch. Then, the reflected light is detected by the light receiving element, and if the light receiving element cannot receive the reflected light, it is recognized as a belt disconnection. This is a belt breakage detection device configured to stop immediately. This device is based on the idea that two belts rarely cut at the same time, and it is possible to increase safety by increasing the number of divisions.

In addition, the environment of the photoelectric switch mounting portion protects the photoelectric switch with a cover or an air blow to prevent the deterioration of the detection function due to the contamination of the lens surface of the photoelectric switch due to the scattering of the coolant and the belt powder, and the stable detection function. It is designed so that long-term safety can be secured by maintaining the above.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a model diagram showing an outline of a belt breakage detecting device of the present invention.

The synchro belt is divided into V1 and V2, the distance setting type phototube switches S1 and S2 are covered with a cover C, and the light from the projector passes through the window W and illuminates the respective synchro belts. A1 and A2 are air blow pipes for injecting clean air so that the coolant liquid and the belt powder do not adhere to the light receiving element surface of the photoelectric tube switch in the cover. When the belt is cut, the reflected light applied to the belt does not reach the light receiving element of the photoelectric tube switch, and the photoelectric tube switch issues an OFF signal. If this signal is used to quickly stop the machine, it will be possible to replace the belt without causing the spindle unit to drop suddenly. In addition, the configuration in which the machine is stopped by the OFF signal of the photoelectric tube switch will issue the OFF signal even when the photoelectric tube switch is broken, so that it can be made to function more safely.

FIG. 2 is a sectional view showing the structure of one type of machining center equipped with the device of the present invention. The Y-axis driving motor M1 is mounted on the X-axis column 1, and the synchro belts V1 and V2 are wound around the motor pulley 3 and the pulley 4 fixed to the shaft end of the ball screw 2. The nut 5 that is screwed to the ball screw is fixed to the main spindle device H, and the main spindle device H moves up and down by the rotation of the ball screw 2. M2 is a spindle motor that rotates the spindle of the spindle device.

When the belt is cut, the sliding resistance of the slide guide rail or the sliding of the ball screw in which the spindle device moves up and down due to the force in the gravity direction of the total mass of the spindle device including the spindle motor M2 attached to the spindle device. The force obtained by subtracting the force such as the dynamic resistance will cause the spindle device to drop. Therefore, by mounting the belt breakage detecting device shown in FIG. 1 on the X-axis column 1, the braking force of the Y-axis drive motor M1 is transmitted to the ball screw via the remaining belt, and the spindle device is rapidly moved. The machine can be stopped immediately without dropping it onto the ground.

[0011]

[Effect of the invention]

 As described above in detail, the machining center that eliminates the balance cinder, which is an obstacle to speedup, is exposed to the risk that the spindle device that moves in the vertical direction will suddenly fall due to the belt cutting. By installing the device, it is possible to know the belt replacement time before the spindle device falls, so it is possible to realize a safe, low-cost machine tool compatible with high-speed operation.

[Brief description of the drawings]

FIG. 1 is a model diagram showing an outline of a belt breakage detecting device according to the present invention.

FIG. 2 is a partial cross-sectional view showing the structure of one type of machining center equipped with the device of the present invention.

[Explanation of symbols]

 A1, A2 Air blow piping C cover H Spindle device M1 Y-axis drive motor M2 Spindle motor S1, S2 Photoelectric tube switch V1, V2 Synchro belt W Window 1 X-axis column 2 Y-axis ball screw 3 Motor pulley 4 Ball screw drive pulley 5 Y Nut for shaft ball screw

Claims (1)

[Utility model registration claims] 1. In a machine tool in which a feed screw shaft (gravitational force direction moving shaft) for moving a spindle device of a machine tool in the vertical direction is moved via a belt, a plurality of vertical moving feed screw shaft driving belts are provided. A photoelectric switch that divides each belt to irradiate the light from the projector and detects the reflected light by the light receiving element is provided, and the photoelectric light that cannot receive the reflected light when any one of the belts is cut Belt breakage detection device configured to operate the switch to stop the machine quickly.