JP4132025B2 - Machine tool chuck drive unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chuck driving device for a machine tool to which the driving force energizing Organization for energizing the driving force, such as a screw feed mechanism.
[0002]
[Prior art]
As a conventional driving force increasing mechanism for increasing the driving force of the driving device, for example, there are a screw feed mechanism and various link mechanisms.
The screw feed mechanism is a mechanism that increases the driving force by converting the rotational force into the forward / backward movement using the screw input of the screw, and the link mechanism is one using a cam or one using the lever principle. It's being used.
In addition, the chuck drive device of a machine tool is known to have a pull chuck configuration using an air cylinder or a hydraulic cylinder.
[0003]
[Problems to be solved by the invention]
However, a large clamping force is required for a chuck of a machine tool, and the structure of the pulling chuck using the air cylinder naturally has a limit in the cylinder diameter, so that a sufficient clamping force cannot be obtained. When a hydraulic cylinder is used, the whole cylinder or the piston in the cylinder must rotate with the chuck, and so-called rotating cylinders are used. In this case, oil leakage occurs or is prevented. Therefore, the upper limit of the rotational speed due to the seal structure is limited.
Therefore, a configuration in which the clamping force is increased by using the driving force increasing mechanism as described above is conceivable. However, the conventional force increasing mechanism such as the screw feed mechanism and the link mechanism can arbitrarily set the rate of increasing force. There wasn't. Further, it is possible to increase the force by using a plate cam or the like, but in this case, the load on the bearing or the like that transmits thrust from the non-rotating part to the rotating part becomes large, so that the configuration is not easily usable.
[0004]
The present invention has been made in view of the above problems, to provide a chuck drive for energizing the chucking tensile force by advancing and retracting operation of the cylinder effectively using any alterable driving force energizing Organization the ratio of energizing Objective.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a chuck driving device that opens and closes a chuck mounted on a spindle of a machine tool, and covers a cylindrical body provided with a first groove cam on the spindle and A second groove cam having a shape different from that of the first groove cam is provided at a position opposite to the first groove cam, and a collar is externally fitted to a draw bar arranged in the main shaft for pulling the chuck and attached to the collar. Provided is a cam follower that engages both the first groove cam and the second groove cam to transmit force, and further has a driving means for relatively moving the first groove cam and the second groove cam in the axial direction of the main shaft. In addition, the driving force generated by the driving means is applied to the first groove cam and the second groove cam, and the force received from both groove cams is transmitted to the cam follower to increase the driving force for the collar. Drawbar chuck Characterized by energizing the tension force.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. Figure 1 is an explanatory view showing an example of the engagement Ru machine tools of the chuck drive apparatus of the present invention, FIG. 2 is an enlarged view of the essential part. In the figure, 1 is a spindle of a machine tool, 2 is a chuck provided at the tip of the spindle and grips a workpiece, 3 is a draw bar that pulls the chuck 2 and fixes the workpiece, and a chuck drive device is provided on the spindle base 1a. A driving force boosting mechanism 4 is formed as a main part.
[0008]
The main shaft 1 is formed in a cylindrical shape, and a draw bar 3 is inserted and disposed on the main shaft central axis M of the internal space. Similarly, a cylindrical cylindrical body 5 is slidably covered on the base 1a of the main shaft 1, and a groove cam as shown in FIG. 3 is provided at a position where the cylindrical body 5 and the main shaft base 1a are engaged with each other. are two locations formed at symmetric positions with respect to the axis M. 3, (a) shows the first groove cam 7 formed in the cylindrical body 5, (b) shows the second groove cam 8 formed in the main shaft base 1a, and the arrow Z indicates the axial direction of the main shaft 1. (The direction of the central axis M) is shown.
[0009]
The first groove cam 7 is formed in a substantially square shape by connecting a first straight line portion 7a inclined approximately 60 degrees with respect to the main axis A and a second straight line portion 7b inclined approximately 30 degrees. . Further, the second groove cam 8 is formed by providing a bent portion 8b formed in a direction inclined approximately 85 degrees with respect to the axial direction at one end of a linear portion 8a formed parallel to the main axis A.
[0010]
Similarly, a collar 9 as a cylindrical moving member is externally fitted inside the main shaft base portion 1a which is the base end portion of the draw bar 3 disposed in the main shaft 1. The collar 9 is mounted on the draw bar 3 with bearings 13 and 13 at the front and rear ends, and is mounted so as to be rotatable in the circumferential direction of the draw bar 3. And it has the cam follower 10 which is inserted and engaged in the 1st groove cam 7 and the 2nd groove cam 8, and moves by the effect | action of both cams.
The cam follower 10 includes a first roller 10b that rotates around the rod-shaped shaft body 10a by engaging with the first groove cam 7, and a second roller 10c that rotates by engaging with the second groove cam 8. And is formed so as to move smoothly in both groove cams.
[0011]
Reference numeral 14 denotes an air cylinder as drive means, and the air cylinder body 14a is rotatably connected to the main shaft 1 via a bearing 15a. The output shaft 14b of the air cylinder 14 is rotatably connected to the cylinder 5 via a bearing 15b.
A key 11 is provided between the main shaft 1 and the cylindrical body 5 so that the first groove cam 7 and the second groove cam 8 do not rotate with each other and can move in the direction of the center line of the main shaft 1. ing.
[0012]
Next, the operation of the chuck driving device having the above configuration will be described. The cylinder 5 and the main shaft 1 are driven by the advancing and retreating action of the air cylinder 14 and relatively move in the direction of the main shaft axis M. Actually, the main shaft does not move in the direction of the axis M, and only the cylinder 5 moves.
At this time, the first roller 10b engaged with the first groove cam 7 moves while being guided by the first groove cam 7, and the second roller 10c moves while being guided by the second groove cam 8. . However, since the first and second rollers 10b and 10c are connected by the shaft body 10a, the cylindrical body 5 having the first groove cam 7 and the main shaft 1 having the second groove cam 8 move relatively.
[0013]
In this way, the collar 9 is driven in the direction of the main shaft center line in addition to the main shaft circumferential direction, and the draw bar 3 is driven in the direction of the main shaft center line via the bearing 13. The draw bar 3 drives the chuck 2 to open and close.
For example, when the air cylinder 14 is extended, the cylinder 5 is pulled in the left direction in the drawing, which is behind the main shaft. Therefore, the cam follower 10 moves in the first groove cam 7 to the upper right in the figure and also moves in the second groove cam 8 to the right in the figure, and the force generated by this action is transmitted to the draw bar 3.
[0014]
With this configuration, the cam follower 10 has the first linear portion 7a of the first groove cam 7 and the second groove cam in the first half of the range in which the claws of the chuck 2 can operate with low thrust until the chuck 2 comes into contact with the workpiece. The draw bar 3 is driven without being increased in the direction of the center line of the main shaft because it moves while engaging with the eight straight portions 8a. In the second half of the operating range, the cam follower 10 engages and moves with the second linear portion 7b of the first groove cam 7 and the bent portion 8b of the second groove cam 8, so that the cam follower 10 is moved to the second groove cam. 8 is driven spirally. That is, the increased force in the direction of the central axis in the operating range in which the thrust of the chuck 2 comes into contact with the work and a high thrust force that causes deformation or compression of an elastic body such as a spring or compressive fluid as a holding force Can be applied to the draw bar 3 to generate a large gripping force on the chuck 2.
[0015]
Further, the air cylinder 14 is supported by a spindle head main body (not shown) so as not to rotate and does not rotate even if the main shaft 1 rotates, so that the air cylinder need not be a rotating cylinder. Therefore, a hydraulic cylinder may be used in place of the air cylinder, and measures such as hydraulic leakage are not required, and the force is effectively increased by the cam, so that high-speed and high-pressure chuck driving is possible.
[0016]
The driving force boosting mechanism has been described by taking the chuck driving device as an example, but it can also be used as a boosting device by providing a groove cam on a flat plate other than a cylinder, etc. be able to. At that time, the shape of the groove cam does not need to be a square shape. For example, the groove cam may be bent in three steps, or may be formed by connecting a straight portion with a large radius. The design should be optimized accordingly. By doing so, the increase in driving force can be arbitrarily changed.
In the above embodiment, two sets of groove cams and cam followers are provided. However, more pairs may be provided, the driving force of the driving means can be dispersed, and the burden of one cam follower can be reduced.
[0017]
【The invention's effect】
As described above in detail , according to the chuck drive device for a machine tool according to the present invention, it is possible to arbitrarily change the driving force increase by forming the first and second groove cams in a predetermined shape. For example, it is possible to move the chuck bar with a low thrust until the chuck claw comes into contact with the workpiece, and to apply the increased force to the draw bar in an operation range where the chuck claw contacts the workpiece and requires a high thrust. .
[Brief description of the drawings]
FIG. 1 is an explanatory view of the shown to machine tools of the chuck drive an example embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3A is a plan view of a first groove cam.
(B) is a top view of a 2nd groove cam.
[Explanation of symbols]
1 .. Main shaft, 1a .. Main shaft base, 2 .. Chuck, 3 .. Drawbar, 4 .. Driving force booster mechanism, 5 .. Cylindrical body, 7 .. First groove cam, 7 a. 7b ··· Second linear portion, 8 ··· Second groove cam, 8a ··· Linear portion, 8b · · Bending portion, 9 · · Collar as moving member, 10 · · Cam follower, · · · 14 as drive means Air cylinder.

Claims (1)

A chuck driving device that opens and closes a chuck mounted on a spindle of a machine tool,
A cylindrical body having a first groove cam provided on the main shaft is covered, and a second groove cam having a shape different from the first groove cam is provided at a position opposite to the first groove cam on the main shaft, and is disposed in the main shaft. The collar is externally fitted to the draw bar for pulling the chuck, and the collar is provided with a cam follower that engages both the first groove cam and the second groove cam to transmit the force, and further includes the first groove. Drive means for relatively moving the cam and the second groove cam in the direction of the spindle axis;
A constant driving force generated by the driving means is applied to the first groove cam and the second groove cam, and the force received from both groove cams is transmitted to the cam follower to increase the driving force for the collar and A chuck drive device for a machine tool characterized by increasing a chuck pulling force.

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