JP3206065B2 - Emergency retraction device for cutting table in machine tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device in the event of an abnormality during the operation of a machine tool. Related to a device for causing

[0002]

2. Description of the Related Art Generally, in a turning machine tool, the operation of a tool and the movement of a workpiece are linked from a single drive source via a gear train, so that when the drive source stops due to a power failure or the like. Since the tool side and the work side stop at the same time, a mechanism for urgently retreating either the tool or the work in the event of a power failure is not provided. However, for example, in a conventional screw grinder using gear transmission, every time the screw lead of the work changes, the gear must be converted in accordance with the change. Grinding machines with NC controlled by NC have been developed. Even in such a grinding machine with NC, a safety mechanism at the time of power failure is not provided at all on the grinding machine main body side, and only an operation maintaining device and a maintenance device at the time of power failure are added to the NC device.

[0003]

In a turning machine in which the operations on the tool side and the work side are synchronized by gear connection, the relative cutting feed between the tool and the work itself stops at the time of a power failure, and the contact between the tool and the work is stopped. There is little danger of tool breakage and the like. However, in the case of an NC machine tool such as the aforementioned grinding machine with NC, in the event of a power failure, for example, a rotation stop position of a work spindle driven by an electric motor or a hydraulic motor, a stop position of a table, and a grinding wheel head operated by NC control. The cutting feed position may vary, leading to a major accident of breakage of the grinding wheel. N
Even if a maintenance device at the time of a power failure is added to the C device, the mutual positional relationship between the grindstone and the work is disrupted because the drive unit on the main body side of the grinding machine stops, and there is a danger of an accident.

[0004] The present invention is directed to a cutting stand in a machine tool in which a cutting stand of a tool or a work automatically retreats in a safe direction in the event of a power failure during a machining operation, and forcibly disconnects the contact between the tool and the work. An emergency retraction device is provided.

Another object of the present invention is to provide an emergency retracting device for a cutting table which can be easily attached to an existing machine tool, has a reliable operation, and can be easily maintained and inspected from outside.

[0006]

According to the present invention, a ratchet wheel fixed to a feed screw shaft of a cutting table, and a pinion gear rotatably supported by the feed screw shaft and having a ratchet pawl arm fixed to a side surface. And the ratchet pawl arm is pivotally attached to the tip of the arm and urged in a direction in which the ratchet wheel meshes with the ratchet claw arm .
A ratchet pawl rotatable about a center; a stopper abutting the ratchet pawl so that the ratchet pawl is separated from the ratchet wheel ;
Is disposed immediately below, and a built-in rack piston meshing with the pinion gear, and forward movement of the rack piston Oyo
And a drive source for moving the rack piston of the cylinder device in an emergency, and the ratchet pawl arm rotates around the center of the ratchet wheel by the movement of the rack piston. The ratchet pawl is turned away from the stopper, and the ratchet pawl and the ratchet wheel are fitted.
Later, the rack of the pinion gear and the rack piston
Predetermined movement of the cutting table of the feed screw shaft by fitting
An emergency retraction device for a cutting table in a machine tool adapted to be rotated in a reversing rotational direction by an amount is provided.

[0007]

When the present invention is applied to an emergency retraction device of a cutting shaft (grinding wheel head) of a grinding wheel shaft of a grinding machine, a ratchet wheel and a ratchet claw fixed to a feed screw of the grinding wheel shaft during normal operation are separated by the stopper. The wheel head is operated by the feed screw independently of the emergency retraction device. If a power failure occurs during this operation, the rack piston of the cylinder device is moved by a pressure supply source that is not affected by the power failure and that is independent of the power supply related to the power failure, such as an air pressure of an air motor or an accumulator. The piston gear meshing with the rack piston and the ratchet pawl arm fixed to the gear rotate, the ratchet pawl is disengaged from the stopper to engage with the ratchet wheel, and the rotation of the ratchet wheel causes the rotation of the grindstone headstock. The feed screw shaft is rotated in the retreating direction of the grindstone headstock.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example with reference to the drawings. FIG. 1 is a front view of a screw grinder according to an embodiment of the present invention, and FIG. 2 is a partially enlarged side sectional view taken along a line AA in FIG. Briefly describing this grinding machine with reference to FIGS. 1 and 2, a work table 16 is mounted on a bed 15 of the grinding machine, and the work table 16 is provided at the rear center of the bed 15 in the moving direction (X direction) of the table. Right angle direction (Y
The cutting table 17 which moves forward and backward in the direction (direction) is placed. A nut 33 screwed to the table feed screw shaft 18 is fixed to the lower part of the table, and the table feed screw shaft 1 is driven by a servomotor 34 attached to the bed 15.
8, the table 16 is reciprocated. The work 21 mounted between the headstock 19 and the tailstock 20 on the table 16 is rotationally driven by another spindle rotation servomotor 35. A grinding wheel 22 is pivotally supported at the front of the notch 17, and a bed 15 is provided at the rear of the notch 17.
The cutting table feed screw shaft 1 is rotatably and axially immovably supported by a shaft support 23 fixed to the upper surface.
The nut portion 24 of the cutting table 17 is screwed. The feed screw shaft 1 penetrates a shaft support 23 on the bed 15 and protrudes rearward thereof. The feed screw shaft 1 has a large-diameter gear 2 for driving a cutting table fixed to the outer periphery of the shaft and a cutting drive motor 4 (FIG. 3). The output shaft is rotated by meshing with an output shaft gear 3 (FIG. 3) provided on the output shaft, whereby a cutting operation of the cutting table 17 is performed. The grinding wheel 22 is rotationally driven by a grinding wheel shaft motor 36 on a cutting table, and the cutting drive motor 4 is controlled by an NC device (not shown).

Referring to FIGS. 2 and 3, a pinion gear 7 is rotatably supported at the rear end of the feed screw shaft 1 of the cutting table 17. The pinion gear 7 meshes with a rack piston 8 of a cylinder device 28 provided on the bed 15 through a notch in the cylinder wall. A ratchet pawl arm 6 is fixed to one end face of the pinion gear 7, and a ratchet wheel 5 is fixed to the rear end face of the large-diameter gear 2 so as to face the ratchet pawl arm 6. As shown most clearly in FIG. 3, a ratchet pawl 9 which can be engaged with the ratchet wheel 5 is pivotally attached to the tip of the ratchet pawl arm 6. The ratchet pawl 9 is always held by the tension spring 29 hooked between the vicinity of the tip of the pawl and the ratchet pawl arm 6.
However, when the grinding machine is in normal operation, it is erected at an appropriate fixed position on the bed 15, for example, at an upper position of the cylinder device 28, and pivots between the tension spring 29 and the ratchet pawl 9. Stopper 1 located between landing point P
The ratchet pawl 9 is lifted by the stopper so that the tip of the ratchet pawl 9 is separated from the ratchet wheel 5 in this state. The ratchet pawl 9, the tension spring 29 and the ratchet pawl arm 6 are similar to the pinion gear 7 in that the notch 1
7 is free to rotate with respect to the feed screw shaft 1.

Both ends of the cylinder chamber of the cylinder device 28 are connected to an air source, for example, an air accumulator 32, via a pipe 31 and an air solenoid valve 11. During normal operation of the grinding machine, the air valve 11 is closed by a driving power supply of the grinding machine. The rack piston 8 is maintained at a position on one side of the cylinder chamber, and in this state, the thread groove grinding operation of the work is performed. If a power failure occurs during this grinding operation, the power to the air valve 11 is turned off, the air solenoid valve 11 is automatically opened by a built-in spring force or the like, the air pressure of the air accumulator 32 is supplied to the cylinder device 28, and the rack piston 8 moves to the opposite side, and the pinion gear 7 meshing with this rotates. In the present invention, the feed screw shaft 1 is forcibly rotated by a rotation operation of a pinion gear 7 rotatably held in the feed screw shaft 1 in a predetermined direction, and
7 is retracted in a direction away from the work. The direction of rotation of the pinion gear 7 at this time is the same as the direction of rotation of the feed screw shaft 1 that retracts the cutting table during normal operation.
The air solenoid valve 11 may be opened simultaneously with the power failure by a power supply of a different system from the power supply related to the power failure.

More specifically, when the ratchet pawl arm 6 rotates in the same direction due to the rotation of the pinion gear 7 in the above-mentioned direction, the ratchet pawl 9 at the tip thereof separates from the stopper 10 and is simultaneously pulled. Spring 29
As a result, the ratchet pawl 9 meshes with the ratchet wheel 5, and the rotation of the pawl arm 6 causes the ratchet pawl 9 to rotate the ratchet wheel 5 in the above-described direction.
The feed screw shaft 1 integrated with the cutting table rotates in the cutting table retreating direction, and the cutting table 17 retreats. Therefore, the danger that the cutting table 17 retreats in the safe direction due to the power failure regardless of the control system of the NC device and the grinding wheel 22 is damaged due to irregular contact with the work can be avoided.

In the above-described embodiment, an example has been shown in which a cutting-table retreating device is added to an existing NC threaded grinding machine. However, the present invention can be applied to other machine tools as well, and a grinding wheel shaft can be used. The emergency retraction device of the present invention is not limited to the case where the present device is provided at the rear of the cutting table to be held, but is provided at the front of the feed screw shaft of the cutting table or at the work cutting table when the work advances and retreats with respect to the tool. Can also be attached. The drive source of the cylinder device that operates the ratchet claw arm may be a hydraulic source instead of the air supply source.

[0013]

As described above, the cutting table emergency retraction device of the present invention is automatically activated simultaneously with a power failure during operation to forcibly reverse the feed screw shaft (reverse rotation).
Since the tool and the workpiece are immediately separated, it is possible to prevent the tool from being damaged or the workpiece from being damaged due to accidental contact between the tool and the workpiece during a power failure. The device of the present invention can be easily attached to the projecting end of the feed screw shaft with only a slight modification such that the feed screw shaft of the tool or work of the existing various machine tools is projected outward, and the entire device is externally mounted. Since it is exposed, it is easy to assemble and adjust, and there is an effect that operations such as maintenance, inspection, and repair can be easily performed from the outside. The present invention is particularly applicable to machine tools with NC and various production machines,
It is useful when applied to a measuring machine with C or the like.

[Brief description of the drawings]

FIG. 1 is a front view of a screw grinder according to an embodiment of the present invention.

FIG. 2 is a partial enlarged cross-sectional view taken along a line AA in FIG. 1;

FIG. 3 is a rear sectional view taken along line BB of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 cutting screw feed screw shaft 2 large diameter gear 3 output shaft gear 4 cutting driving motor 5 ratchet wheel 6 ratchet claw arm 7 pinion gear 8 rack piston 9 ratchet claw 10 stopper 11 air solenoid valve 17 cutting table 21 work 22 grinding wheel 24 nut part 28 Cylinder device 29 Tension spring 32 Air accumulator

Claims (2)

(57) [Claims] 1. A ratchet wheel fixed to a feed screw shaft of a cutting table, a pinion gear rotatably supported by the feed screw shaft and having a ratchet pawl arm fixed to a side surface, and a pivot at a tip end of the ratchet pawl arm. wear is and the is biased in a direction meshing with the ratchet wheel La
A ratchet pawl rotatable around the center of the ratchet wheel, a stopper abutting on the ratchet pawl so that the ratchet pawl is separated from the ratchet wheel , and a pinion gear disposed immediately below the feed screw shaft ; a built-in rack piston meshing, and the rack
A cylinder device for performing forward and backward movements of the piston by a working fluid, and a drive source for moving a rack piston of the cylinder device in an emergency, and the ratchet claw arm is moved by the movement of the rack piston. Said ratchet
It is rotated about the center of Lumpur away from said ratchet pawl the stopper, and the with the ratchet pawl ratchet
After the wheel is fitted, the pinion gear and the rack
Cut of the feed screw shaft by fitting the cup piston rack
An emergency retracting device for a cutting table in a machine tool, wherein the cutting table is rotated in a reverse rotation direction by a predetermined moving amount . 2. A driving source of the cylinder device is an air accumulator, and a pressurized air is supplied to the cylinder device from the air accumulator through an air valve which is opened when a driving power supply of the cutting table is cut off. 2. The emergency retraction device for a cutting table in a machine tool according to claim 1, wherein: