JPH0446702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an automatic release device for chip clogging in a chip conveyor.

BACKGROUND TECHNOLOGY In workpiece machining processes using numerically controlled machine tools, continuous unmanned operation under computer control has been implemented in order to improve production efficiency and save labor. Under these conditions, the chips generated during machining of the workpiece are continuously discharged out of the system along with the cutting fluid by a chip conveyor that moves at a constant speed, and the chips are deposited onto the table of the numerically controlled machine tool. Creates a clean workpiece cutting environment with no buildup.

Problems to be Solved by the Invention When performing continuous unmanned operation as described above, the workpiece supplied to the numerically controlled machine tool is automatically machined according to a preset machining program. There are many points that need to be improved in order to prevent accidents regarding the automatic discharge of chips that are generated. For example, in a conventional chip conveyor device in which a chip scraping plate is attached to an endless conveyor chain, there is a gap between the main body of the chip conveyor that moves at a constant speed and the chip receiving surface, or between the chain and its guide member. There is a built-in safety device that stops the constant speed movement of the chip conveyor by causing the disk spring of the torque limiter installed on the drive shaft of the chip conveyor to slip when chips get caught in the chip conveyor's drive shaft. In this case, since the drive motor continues to rotate even after the chip conveyor has stopped, clogging of chips is accelerated and heat generation may cause an accident such as a fire, which poses a safety problem. Another method is to use a shock relay, but
Safety devices that detect instantaneous changes in current value are not only difficult to set the level of current value that corresponds to normal conditions and when jamming occurs, and are not only subject to restrictions on operating accuracy, but also cost-intensive. It is also expensive and impractical. In any of the above safety devices, the amount of chips that accumulate on the chip conveyor will be reduced because cutting of the workpiece continues even after the chip conveyor has stopped due to chips being caught in the chip conveyor. It increases as the workpiece machining time progresses. As can be understood from the above explanation, all existing automatic stop means have a fundamental problem of reduced safety due to poor operating accuracy, and there is a strong demand for a solution to this problem. There is.

A principal object of the present invention is to provide a solution to the above-mentioned problems found in conventional automatic chip conveyor stopping devices.

Means for Solving the Problems In view of the above object, the present invention provides a torque limiter which is installed between the chip conveyor drive motor and the chip conveyor drive shaft and slips when the torque exceeds a set torque, and a torque limiter which is fixed to one end of the chip conveyor drive shaft. a starting dog, a switching means that is fixed on the rotation locus of the starting dog and generates an ON/OFF signal according to the rotation of the starting dog, and an ON/OFF signal of the switching means.
It is equipped with a chip conveyor drive motor control circuit that controls the chip conveyor drive motor to reverse rotation for a predetermined time and return to normal rotation when either one of the OFF signals continues to occur for a predetermined time or more. be.

Function The stoppage of the chip conveyor due to chips being caught is detected by a switch means such as a limit switch or a proximity switch, and the chip conveyor drive motor is reversed for a predetermined period of time to automatically release chips from being caught. do. After the jammed state is released, the chip conveyor drive motor switches from reverse rotation mode to normal rotation mode, and automatic discharge of chips by the chip conveyor is restarted.

Embodiment FIG. 1 is a schematic cross-sectional view of the essential parts of the apparatus of the present invention, and FIG. 2 is a chart diagram illustrating the transmission state of a reversal signal of the chip conveyor. FIG. 3 is a front view of the boot dock. As seen in these drawings, a first chain wheel 4 is fixed to the drive shaft of a motor 3 with a reduction gear, which is fixed to a base plate 2 via a tension adjustment bolt 1 so as to be height adjustable. Correspondingly, a second chain wheel 7 with a torque limiter 6 is fixed to one end of the chip conveyor drive shaft 5.
At the other end of the chip conveyor drive shaft 5,
Proximity switch LS for detecting stoppage of chip conveyor 8
A boot dock 10 is fixed thereto. The start-up dock is caused by chips clogging between the scraping plate (indicated by reference number 9 and a two-dot chain line) of the chip conveyor 8 and its moving surface 11, resulting in a disc spring (not shown) incorporated in the trick limiter 6. When the rotation of the chip conveyor drive shaft 5 stops due to slippage, a stop signal is sent to the stop detection proximity switch LS mounted on the lower edge of the base plate 2, as shown in FIG. It is mounted as a concentric end cam with a major diameter portion and a minor diameter portion each having a phase angle of approximately 180°.
On the other hand, the chip conveyor control circuit connected to the stop detection proximity switch LS of the chip conveyor 8 has
Chip conveyor detection timers T ₁ , T ₂ , reversal time setting timer T ₃ , etc. are connected via relays (not shown) in accordance with a conventional method. These timers can be appropriately selected from commercially available mechanical timers, sequence timers, and the like.

Hereinafter, the operating state of the device of the present invention will be explained based on FIG. When no chips are caught at a chip conveyance speed of 3 m/min,
The chip conveyor drive shaft 5 rotates at a low speed of 8.5 revolutions per minute. In this state, the proximity switch LS for detecting the stoppage of the chip conveyor 8 operates at a rate of 2 times per revolution of the chip conveyor drive shaft 5 in response to the constant speed rotation of the starting dog 10, as illustrated in FIG. 2A. It performs ON/OFF operations and sends a sawtooth operating signal to timers T ₁ and T ₂ for detecting the stoppage of the chip conveyor via a relay (not shown). On the other hand, when chips are caught during machining of a workpiece, the chip conveyor drive shaft 5 is stopped by the disc spring of the torque limiter 6 slipping. At this time, as shown in FIG. 2B, the proximity switch LS
is in the OFF state, the transmission of the ON signal from the proximity switch LS is interrupted, and the operation signal from the first timer _T1 arranged corresponding to the proximity switch LS disappears. . The setting time of the first timer _T1 (about 7 seconds in this example)
When , a reversal start signal is sent to a reversal time setting timer _T3 provided in the chip conveyor control circuit via a relay (not shown). As a result, the rotational direction of the motor 3 with a speed reducer is switched from the normal rotation state to the reverse rotation state, and the chip conveyor 8 rotates in the reverse direction for the time set by the timer _T3 for setting the reversal time. In this way, the chips caught between the scraper plate 9 of the chip conveyor 8 and its moving surface 11 are released, and the chip conveyor 8 recovers its chip discharge function. When the time set by the timer _T3 for setting the reverse rotation time has elapsed, the rotation direction of the motor 3 with a reduction gear is switched from the reverse rotation state to the normal rotation state again, and the chip conveyor 8 returns to the normal operation mode. Figure 2C shows the transmission state of the reverse rotation signal when the chip conveyor drive shaft 5 has stopped due to chips being caught and the proximity switch LS is placed in the ON state and continues to send the ON signal. It shows. In this case, the operation signal from the second timer _T2 disposed corresponding to the proximity switch ON disappears;
The operating procedure of the timer _T3 for setting the reversal time using the timer _T2 is the same as that of the first timer _T1 , so a description of the overlapping matters will be omitted.

It should be noted that the above embodiments are for illustratively explaining the present invention, and the scope of rights of the present invention should not be construed as being limited based on such descriptions. For example, a non-contact detector such as a limit switch, photodiode, phototube, etc. can be used instead of the proximity switch. Furthermore, the rotational speed of the chip conveyor can be freely selected depending on the machining conditions of the workpiece.

Effects of the Invention According to the present invention, it is possible to prevent malfunctions due to rapid fluctuations in current value at the time of startup of the chip conveyor drive motor and at the start of forward and reverse rotation, and to prevent chips from getting caught in the chip conveyor, causing the set torque of the torque limiter. When a slip occurs in the chip conveyor drive shaft beyond the specified time, the start dog stops rotating and the switch means continues to generate either an ON signal or an OFF signal, and this signal is maintained for a predetermined period of time or longer. When the operation continues, the chip conveyor drive motor is controlled to rotate in reverse for a predetermined period of time and return to normal rotation again, making it possible to easily and reliably release the chips from being jammed. In particular, the simple structure of combining a torque limiter, a starting dog, and a switching means has the advantage of preventing malfunctions of the control circuit and simplifying the device.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the essential parts of the apparatus of the present invention, and FIG. 2 is a chart diagram illustrating the transmission state of a reversal signal of the chip conveyor. FIG. 3 is a front view of the starting dog. 3... Chip conveyor drive motor (motor with reducer), 5... Chip conveyor drive shaft, 6...
Torque limiter, 10...Start dog, LS...
Limit switch or proximity switch, T ₁ ,
T ₂ , T ₃ ... timer.

Claims (1)

[Claims] 1. A torque limiter that is installed between the chip conveyor drive motor and the chip conveyor drive shaft and slips when the torque exceeds a set value, a starting dog that is fixed to one end of the chip conveyor driving shaft, and a starting dog that is fixed on the rotation trajectory of the starting dog. by the rotation of
A switch means that generates an ON/OFF signal, and when either one of the ON/OFF signals of the switch means is generated continuously for a predetermined time or more, the chip conveyor drive motor is reversed for a predetermined time and then returned to normal rotation. 1. An automatic release device for chip jamming in a chip conveyor, comprising: a control circuit for a chip conveyor drive motor that controls the chip conveyor;