JP2521976Y2 - Hydraulic mechanism of spindle tool attachment / detachment device - Google Patents

Description

The present invention relates to a hydraulic mechanism of a spindle tool attaching / detaching device of a machine tool.

2. Description of the Related Art When performing tool change with an automatic tool changer (hereinafter referred to as ATC), the exchange arm grips a tool on a spindle, and then pushes a collet pull-up rod with a hydraulic cylinder device provided at the rear end of the spindle to remove the plate. Kill the spring force, open the collet, loosen the clamp and pull out the tool. After inserting the tool held by the exchange arm into the main shaft, the operation of the hydraulic cylinder device is eliminated, the pull-up bar is pulled up by the force of the disc spring, the collet is closed, the tool is clamped, and the exchange arm is retracted.
The tightening and loosening operations of the tool are generally performed during the ATC exchange operation, and the exchange operation is controlled at a high speed by operation control using a cam. However, if the replacement time is to be further reduced, coordination between the tightening and loosening operations on the spindle side and the tool gripping operation of the replacement arm occurs, and a tool drop accident occurs.
For example, Japanese Patent Application Laid-Open No. 60-201848 is known in consideration of the prevention of tool drop that occurs to shorten the replacement time, and this spring has a spring-like holding claw between the collet in addition to the collet for gripping the tool. The holding claw holds the tool so that the tool does not drop even if the collet is opened before the replacement arm grips the tool, and the replacement arm overcomes the spring force of the holding claw to pull out and insert the tool. Things.

The problem to be solved by the invention Japanese Patent Application Laid-Open No. 60-201848 described in the prior art discloses that before the exchange arm grips the tool, the lifting rod is pressed against the force of the spring by the hydraulic cylinder device at the rear end of the spindle. The collet is released by pushing it down, but the tool expands due to thermal expansion of the tool during cutting and fretting phenomena caused by cutting vibration and oxidative sticking. The tip of the pull stud of the tool is pushed with the tip of the rod to push the tool slightly (0.5 to 0.8 mm) to release the bite. In this way, the collet is opened and the tool is slightly pushed out, and the holding claw is held by the spring force to the extent that the tool does not drop, so there is no problem with normal light biting, but the biting is firm. In such a case, a large repulsive force is generated when the tool is pushed out and comes out. It has been experimentally proved that this repulsive force is a force corresponding to 4 to 5 times the tool weight. When such a repulsive force acts, there is a problem that the tool cannot be held by the force of the spring of the holding claw and the tool falls.

The present invention has been made in view of the above-mentioned problems of the prior art, and the purpose of the present invention is to cause a tool drop accident due to a repulsive force when the tool is pushed out due to biting between the spindle taper hole and the tool. It is an object of the present invention to provide a hydraulic mechanism of a spindle tool attaching / detaching device that does not have the above.

Means for Solving the Problems In order to achieve the above object, the hydraulic circuit of the spindle tool attaching / detaching device according to the present invention includes a collet for gripping a mounted tool, and a tool for gripping the tool and after releasing the tool grip of the collet. In a spindle tool attaching / detaching device having a holding claw for holding a tool incorporated in a main shaft and a hydraulic cylinder piston member for releasing grip of the collet, a pressure reducing valve for reducing a source pressure to a pressure at which the holding claw is not opened. A switching valve for switching the pressure oil depressurized by the pressure reducing valve and sending the pressure oil to the hydraulic cylinder, a bypass path for directly supplying the original pressure to the side chamber for releasing the grip of the collet of the cylinder, and a bypass path provided in the middle of the bypass path. The opening / closing valve is provided to send the pressurized oil depressurized by the operation of the switching valve to the side chamber to be opened, open the collet, and then open the opening / closing valve to open the bypass passage. This is a two-stage operation in which the main pressure is sent and a sharp high-pressure wave loosens the biting of the taper fitting between the main shaft and the tool.

Action The switching valve is switched according to the NC tool change command, and the hydraulic oil is supplied to the hydraulic cylinder with pressure oil reduced to a weak pressure enough to deflect the coned disc spring. Immediately before the replacement arm grips the tool, open and close the bypass by switching the open / close valve, send the high pressure source pressure to the cylinder, and press the pull stud end with the tip of the tool pull rod to slightly hold the tool. Extrude the tool,
At the same time as the exchange arm grips the tool, the bite of the taper fitting between the spindle and the tool is loosened.

Embodiment An embodiment will be described with reference to FIGS.

For example, a spindle 1 rotatably mounted on a spindle head of a machining center is provided with a through hole at the center thereof, and the through hole has a tapered hole 1 having a tapered shank Ta of a tool T mounted thereon.
a, annular grooves 1c, 1d are formed in the straight hole 1b following the straight hole 1b, and are constituted by a straight small-diameter hole 1e, followed by a large-diameter hole 1f. A known collet 2 split into two in the vertical direction is inserted into the straight hole 1b, and a plate-like holding claw 3 is symmetrically interposed between the collets 2. The holding claw 3 has a jaw 3a which engages with the pull stud Tb of the tool T on the inside of the tip, an engagement step 3b formed at a slight interval, and an annular groove on the outside.
A convex portion 3c which becomes a fulcrum by engaging with 1d, a convex portion 3d inside the convex portion 3d facing the outer periphery of the pulling rod described later with a slight gap, and a convex portion facing the outer peripheral portion of the pulling rod further away with a slight gap inside. 3e, the space between the step 3b and the projection 3c acts as a spring.

The pull-up rod 4 of the collet 2 projects backward from the center holes 1b, 1e, 1f of the main shaft 1, and a jaw 4a for pulling in the collet 2 is cut into the tip of the pull-up rod 4, and the holding claw 3 is assembled. At times, the notches 4b, 4c into which the inner convex portions 3c, 3e enter are cut out, and a step for regulating the pulling position is formed on the step of the small diameter hole 1e on the way,
A screw is engraved on the protruding end. A plurality of superposed disc springs 5 are inserted into the large-diameter hole 1f of the main shaft 1 and are incorporated so as to generate a pulling force with a stop seat 6 fixed to the pulling rod 4. A tool clamp checking dog disk 7 is fixed to the pulling rod, and a position detecting non-contact type detector 9 is attached to a cylinder cylinder 8 fixed to the spindle head. Further, the second end face is formed on the protruding end of the pulling rod 4.
As shown in the figure, a backing plate 10 having two parallel surfaces 10a is attached.

A piston 12 is fitted into the cylinder 11 of the cylinder cylinder 8, and a piston rod 13 penetrating both wall surfaces of the cylinder 11 is fixed to the piston 12. This piston rod 13
A parallel groove 13a that fits with the two parallel surfaces 10a of the contact metal 10 is cut to a predetermined depth on the end surface of the pulling rod side. This depth is equal to or slightly longer from the grip release position of the collet 2 to the grip release position of the holding claw 3. A dog 14 is attached to the rear end of the piston rod, and the limit switch is operated when the gripping claw is released and the gripping is completed. An axial keyway 14a is cut into the dog 14, and the parallel groove 13a
The key 15 is mounted on the cylinder 8 so that the phases of the two parallel surfaces 10a and the parallel grooves 13a of the pad 10 when the main shaft 1 is oriented at the time of tool change are aligned.

As shown in the circuit diagram of FIG. 1, a hydraulic circuit for supplying pressure oil to the cylinder 11 has a source pressure P communicated with a pressure reducing valve 17 through a line 16 and a check valve 19 in the middle of the line 18 from the pressure reducing valve 17. And is communicated with the electromagnetic switching valve 20. Then, from the electromagnetic switching valve to the rear chamber (right chamber) of the cylinder 11 through the pipe 21, the pipe 22
Thus, the tank 11 communicates with the front chamber (left chamber) of the cylinder 11 through the return line 23. Further, bypass pipes 24 and 25 are provided from the middle of the pipe 16 (source pressure P) to the middle of the pipe 21, and an electromagnetic on-off valve 26 is provided between the pipes 24 and 25. As the solenoid on-off valve 26, a shut-off valve with no internal leakage is used. At the moment when the bypass lines 24 and 25 are opened, a sharp high-pressure wave higher than the original pressure P is generated. , 21 via cylinder 1
1 is to be transmitted to the right ventricle.

 Next, the operation of the present embodiment will be described.

Now, the piston 13 of the cylinder 11 is in the retracted position and the tool T
However, it is assumed that the collet 2 is attached to the tapered hole 1a of the main shaft 1, the pulling rod retracts the collet 2 by the force of the disc spring 5, and the tool T is fitted as shown in FIG. The spindle 1 is moved to the tool change position and oriented according to the automatic tool change command. In this state, the phase of the parallel groove 13a at the end of the piston rod 13 of the cylinder 11 and the phase of the two parallel surfaces 10a of the backing plate 10 at the end of the pulling rod 4 match. When the exchange arm (not shown) enters a turning operation for holding the tool T, the electromagnetic switching valve
The 20 solenoids SOL1 are energized and switched to the II position,
The pressure oil depressurized by the pressure reducing valve 17 is supplied to the right chamber of the cylinder 11 via the pipe line 21, and the piston 12 and the piston rod 13 are advanced toward the main shaft 1, and the parallel groove 13a at the end of the piston rod 13 is provided.
Is fitted on the parallel II surface 10a of the backing plate 10 and the groove bottom comes into contact with the pulling rod 4 against the force of the disc spring 5 to push the collet 2 forward. A ring-shaped spring is fitted on the root side of the end of the collet 2 and the collet 2 always tries to open outward by the force of this spring, so that the peak outside the tip falls into the annular groove 1c, and FIG. Like collet 2
Releases the grip of the pull stud Tb of the tool T. Then, the outer periphery of the pulling rod 4 slides on the surfaces of the convex portions 3d and 3e of the holding claw 3, and the front end surface comes into contact with the end surface of the pull stud Tb. At this time, pull bar 4
The forward end position of the piston 12 is determined so that the pushing amount remains slightly (0.5 to 0.8 mm), but the pressure oil depressurized by the pressure reducing valve 17 is adjusted to a pressure enough to deflect the disc spring 5. Therefore, there is no force enough to push out the tool biting into the spindle tapered hole 1a, the pulling rod 4 stops here, and the holding of the holding claw 3 is continued. The signal from the position detector detects immediately before the exchange arm that has swung in this state grips the tool T, and detects the solenoid SOL2 of the solenoid on-off valve 26.
Is switched to the IV position and the bypass lines 24 and 25
Communicates with each other to supply the original pressure to the right chamber of the cylinder 11 and, at the same time, generate a sharp high-pressure wave generated when the on-off valve is switched.
The tool that bites into the spindle taper hole 1a is slightly pushed out (0.5 to 0.8 mm). Even if the tool T thus pushed out attempts to jump out overcoming the gripping force of the holding claw 3, there is no danger of falling because the replacement arm has already gripped the tool T at this time. At this time, the backflow is prevented by the check valve 19 in the middle of the pipeline so that the original pressure P supplied to the right chamber of the hydraulic cylinder 11 does not flow backward to the pressure reducing valve 17 and is not damaged. Next, the holding claw 3 in the gripping state by the force of the axial movement of the exchange arm is bent outward by the spring component due to the external component force due to the inclination of the engagement portion, and the tool is pulled out outward. During this tool removal, the solenoid SOL2 is de-energized, the solenoid on-off valve 26 is switched to the position III, the space between the bypass lines 24 and 25 is closed, and the pressure oil supplied to the right chamber of the cylinder 11 is reduced in pressure. Only the pressure reduced by the valve 17 is obtained. Next, when the exchange tool is rotated by 180 ° and the replaced tool T is inserted into the spindle tapered hole 1a, the solenoid is
SOL1 is de-energized, the electromagnetic switching valve 20 is switched to the I position, and pressure oil is supplied to the left chamber of the cylinder 11 through the pipe line 22,
The piston 12 and the piston rod 13 retreat to the side opposite to the main shaft, the pulling bar 4 is pulled up by the force of the disc spring 5, the collet 2 closes and the tool T is clamped.

Next, when the tool T mounted on the main shaft 1 is manually changed for checking or the like, the main shaft 1 is rotated so as to be removed from the orientation position, and the parallel groove 13a at the end of the piston rod 13 and the parallel two surfaces 10a of the contact plate 10 are rotated. Out of phase. The solenoids SOL1 and SOL2 of the solenoid-operated switching valves 20 and 26 are simultaneously energized and switched to the II position and the IV position, respectively, and the pressure oil and the source pressure reduced through the pressure reducing valve 19 are simultaneously sent to the right chamber of the cylinder 11, When the piston rod 13 is advanced to the main shaft side, the end of the piston rod 13 comes into contact with the end of the backing plate 10, and the pulling rod 4 opens the collet 2 and its tip comes into contact with the end face of the pull stud. Also, the end of the pulling rod 4 abuts the step 3b of the holding claw 3 to open the holding claw 3 to release the grip of the tool, and easily pull out the tool by hand. Can be.

Effects of the Invention Since the present invention is configured as described above, the following effects can be obtained.

Pressure oil reduced to a weak force enough to loosen the disc spring by the pressure reducing valve is supplied to the tool grip open side of the cylinder, pushes out the tool lifting rod, opens only the collet, and opens and closes immediately before the replacement arm grips the tool By switching the valve and supplying the original pressure to the cylinder and slightly pushing out the tool pulling rod, the bite of the taper fitting between the main shaft and the tool was loosened,
The high pressure wave generated when the on-off valve is switched is transmitted to the cylinder, so that the tool can be easily separated even in a state where the tool bites into the main shaft. However, at this time, the tool does not drop because the exchange arm has already gripped the tool. Also, when inserting a tool into the main spindle taper hole, the end of the pull stud collides with the tip of the tool pulling rod, but the pulling rod is pressed with a weak force by the decompressed pressure oil, so the impact at the time of collision decreases and the operation is stable .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a spindle tool attaching / detaching device of the present invention and a spindle including a hydraulic circuit thereof, FIG. 2 is an end view of a pad, FIG. 3 is an end view of a piston rod facing the pad, FIG. The figure shows a tool gripping state of the main spindle, and FIG. 5 is a view AA of FIG.
FIG. 6 is a sectional view of the pulling bar, the collet, and the holding claw along line BB in FIG. 4, and FIG. 7 is a state diagram of the automatic tool loosening. 1 ... spindle 2 ... collet 3 ... holding claw 4 ... pulling rod 11 ... hydraulic cylinder, 12 ... piston 17 ... pressure reducing valve, 20 ... electromagnetic switching valve 24, 25 ... bypass line 26 …… Electromagnetic on-off valve

Claims (1)

(57) [Scope of request for utility model registration] A collet (2) for gripping a mounted tool (T), and a holding claw (3) for gripping the tool (T) and holding the tool (T) even after releasing the tool grip of the collet. In a spindle tool attaching / detaching apparatus having a hydraulic cylinder (11) and a piston (12) member for releasing the grip of the collet, the source pressure (P) is such that the holding claw is not opened. A pressure reducing valve (17), a switching valve (20) for switching the pressure oil depressurized by the pressure reducing valve to the hydraulic cylinder (11) and a side chamber directly releasing the grip of the collet of the cylinder. It includes a bypass passage (24, 25) for supplying pressure and an on-off valve (26) provided in the middle of the bypass passage, and sends the pressure oil depressurized by the operation of the switching valve to the side chamber to be opened. After opening the collet, open the on-off valve and bypass Ri hydraulic mechanism of the spindle tool attachment apparatus characterized by being configured in two step operation to loosen the attached eating taper fitting the spindle and the tool in a peak high pressure wave send original pressure.