GB2057948A

GB2057948A - Turret with revolving tool- holding flange

Info

Publication number: GB2057948A
Application number: GB8025423A
Authority: GB
Original assignee: TAGLIOLI G
Current assignee: TAGLIOLI G
Priority date: 1979-08-10
Filing date: 1980-08-05
Publication date: 1981-04-08
Also published as: IT7903482A0; FR2462955B1; DE3029927A1; FR2462955A1; GB2057948B; IT1120816B

Abstract

Rotation of a single lever 11 on the tool turret causes a shaft 8 with eccentrics 9, 10 simultaneously to move a rod 12 for unlocking a rotatable tool-holding flange on the turret and a rod 13 with a pawl 17 for turning a sprocket wheel 6 coaxially fixed to the flange. Rotation of the lever 11 in the return direction causes the eccentric 10 to force the rod 12 into a flange locking bush to retain it and help keep the flange rigid. <IMAGE>

Description

SPECIFICATION Turret with revolving tool-holding member This invention relates to a turret with a rotata ble tool-holding member, to be applied on centre lathes.

It is well known that in the manufacture of technical parts on a centre lathe, many different tools (mounted each time on a tool holding turret which is connected to the lathe carriage) are generally used to carry out elementary steps of the working process.

When pieces are mass-produced, these tools are used according to a cyclical succession: it is easy to realize that the time wasted to replace the tools bears heavily on the total time required to make a single piece.

This drawback can be avoided if many pieces have to be mass-produced, in which case numerically controlled machines can be used: every step of the working process, including tool-positioning, is wholly programmed and automated. If a small number of identical pieces have to be produced, on the contrary, the use of this machine is not convenient, owing toits high cost and to the high cost of programming the working process. In this latter case, working time can be reduced if one uses turrets with a revolving flange, on which many different tools are fixed. During the working phase the flange is locked in such a way that the tool to be used faces the workpiece. For the following elementary working phase one has to unlock the flange, turn it until the next tool needed faces the workpiece, and then lock the flange again.

In this way, replacing the tool is faster than in the cases in which the tool must be fitted on the turret each time. This is, however, a twohand operation: the operator uses one hand for a locking-unlocking lever and the other hand for a lever to rotate the tool holding flange. Carrying out many elementary operations is also required.

The present invention provides a turret having a revolving tool-holding flange or member that can rotate around an horizontal axis, where locking, rotation, and unlocking of the flange or member are carried out through the rotation of the main shaft by operating only one lever.

In a preferred embodiment, locking and unlocking operations and the contemporary partial rotation of a tool-holding flange are carried out through reciprocating motion of control elements controlled by two eccentrics on a drive shaft. When the first one of the two elements moves forward (controlled by the first eccentric), it fits in an eccentric hole in the flange, locking it, while its backward movement unlocks the flange. When the second one of those elements (which preferably has a pawl placed at the opposite end with respect to the end which cooperates with the second eccentric) moves forward under the action of the second eccentric the pawl engages on a sprocket wheel fixed to the toolholding flange, which causes a partial rotation of the flange; when it moves backward, the pawl slides on the sprocket wheel and it does not cause a reverse rotation of the flange.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation of a turret, in partial section; Figure 2 is a top view, in partial section; and Figure 3 is an axonometric view of the kinematic chain of the turret.

An externally parallelepiped-shaped turret 1 is fixed on the lathe carriage in the same way as the currently used turrets. The shaft 2 of a tool-holding flange 3 (on which the tools are fixed) can rotate about a horizontal axis in the turret 1. The flange 3 is connected to the turret through a self-lubricating bushing 4 and it is axially positioned by means of a spacer 5, a sprocket wheel 6, and a nut 7.

The kinematic chain of the turret 1 comprises a shaft 8 which has eccentriu3 9 and 10; the rotation of the shaft 8 is controlled by a lever 11. The eccentrics 9 and 10 controls the movements of control rods 12 and 13 respectively: the first rod 12 allows the locking of the tool-holding flange 3, while the second rod 13 allows the flange 3 to be partially rotated by action on the sprocket wheel 6, which means that the next tool can be moved to face the workpiece. Both rods 12 and 13 slide in bushings.

At the locking position A' of the lever 11 (Fig. 3) the eccentric 9 forces the rod 12 into a hole with a centering bush 14 made in the flange 3. The rotation of the lever 11, together with the shaft 8, from the position A' to the position A" allows, owing to the thrust of a spring 15 on a seager ring 16, the rod 12 to move from the position B' to the position B" with consequent disengagement of the rod 12 from the bush 14 and the unlocking of the flange 3, which therefore can rotate.

In addition to the unlocking operation, the rotation of the shaft 8 also causes the rotation of the eccentric 10 and the conse luent movement of the rod 13 from the posit.on C' to the position C": a pawl 17, kept close to the sprocket wheel 6 by a compressed spring 18, accordingly causes a partial rotation, from D' to D", of the sprocket wheel 6 (and of the tool holding flange 3, on which sprocket wheel is keyed).

To complete the change of tool it is only necessary to rotate the lever 11 back in the opposite direction: in this way, the eccentric 9 forces the rod 12 by fit into the next hole with a centering bush 14, locking again the tool holding flange 3; it is worth noting that the backward movement of the rod 13 caused by the rotation of the eccentric 10 does not create any rotation or rotating effect of the sprocket wheel 6 because a pawl 17 slides on the teeth of the sprocket wheel, owing to its particular shape.

It is therefore possible to see that, with a simple 1 80' clockwise rotation followed by an equal counterclockwise rotation of the lever 11, it is possible to change the tool to be used at the specific working stage. The number of the teeth in the sprocket wheel 6 and the number of the holes with centering bushes 14 in the flange 3 correspond to the maximum number of tools that can be fixed to the tool-holding flange 3.

Obviously, starting from the position A' a partial rotation of the lever 11 unlocks the flange 3, which is therefore made idle: this can allow the hand rotation of the flange 3 in order to place the tools in succession.

With a suitable scaling of the different elements, the locking method used allows the rod 12 can be slightly axially forced against the flange 3; that stiffens the whole system, which results in a better working allowance to the machine tool compared with the one of the traditional tool-holding flanges where the locking is usually carried out on the shaft 2.

Claims

1. A turret having a rotatable tool-holding member, means for locking and unlocking the tool-holding member, and means for rotating the tool-holding member, the said means being operated by a single lever which controls the locking, unlocking, and rotating of the tool-holding member.

2. A turret as claimed in claim 1, in which the rotating means comprises a toothed wheel coaxially fixed to the tool-holding member and a reciprocating member cooperating with the teeth of the wheel so that one reciprocation turns the wheel through the angle between successive teeth.

3. A turret as claimed in claim 1 or 2, in which the locking and unlocking means comprises a reciprocating member engageable in successive locating holes spaced on a circle coaxial with the tool-holding member.

4. A turret as claimed in claim 3, in which the locating holes are formed in the toolholding member.

5. A turret as claimed in claim 4, in which the reciprocating member of the locking and unlocking means bears axially against the tool-holding member when engaged in a said hole.

6. A turret as claimed in any of claims 1 to 5, in which the said means are operated by rotation of the lever about one axis only.

7. A turret as claimed in claim 6, in which rotation of the lever rotates a shaft having eccentrics controlling the respective means.

8. A turret substantially as described with reference to, and as shown in, the accompanying drawings.