JPH0151282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a machine tool having a double-acting tightening cylinder that operates a tightening device, and when the tightening cylinder is outside the operating stroke, the drive device of the machine tool that processes the workpiece stops or an opening/closing rod which is restrained and coupled to the clamping piston of the clamping cylinder has an opening/closing piece with at least two opening/closing cams;
A sensor provided corresponding to each of these opening/closing cams and operable by these opening/closing cams monitors the movement of the opening/closing rod within a predetermined operating stroke, taking into account the additional tightening stroke, and determines the opening/closing position of the sensor by the opening/closing cam. A machine tool tightening device with variable
In particular, the present invention relates to a device for determining the range of motion of a double-acting tightening cylinder operating an exchangeable chuck of a lathe.

The power operated pawl chuck of the operating clamping device is operated by a compressed air or hydraulic cylinder mounted on the end of the spindle of a conventional machine tool. The clamping device and the clamping cylinder are fixedly connected to each other by a pull rod or a pull tube. When opening and closing the clamping device, the piston of the clamping cylinder performs a reciprocating movement, resulting in a proportional movement of the clamping element. The end position of the total stroke of the clamping device is defined by the maximum movement play of the clamping device or by the maximum possible stroke of the clamping piston in the clamping cylinder.

If the workpiece is clamped approximately at the end of the stroke of the clamping element, there is a risk that the clamping force necessary for machining the workpiece will not be fully generated. This is because the full stroke of the clamping device has already been reached due to the clamping element cutting into the workpiece or due to the deformation of the workpiece that occurs during clamping. In these cases, the conventional monitoring of the hydraulic or pneumatic clamping pressure erroneously gives the impression that sufficient clamping force is present when it is not.

In order to eliminate safety defects, it is known to monitor the position of the clamping piston instead of the position of the clamping element of the clamping device. For this purpose, a closing rod connected to the clamping piston of the clamping cylinder is pulled out rearwardly from the clamping cylinder. The opening/closing rod operates one or more limit switches via opening/closing cams. This limit switch is set to generate an electrical signal just before reaching the end position of the clamping device's complete stroke, which signal indicates an uncertain workpiece clamping and also controls the drive unit for machining the workpiece. Also used to stop or restrain. It is best to stop or restrict the main shaft drive of the machine tool.

Since the total stroke length of the tightening device to be monitored varies depending on the construction of the tightening device, replaceable opening/closing cams or adjustable limit switches are used in the prior art. The known tightening stroke monitoring devices therefore have to be carefully adjusted each time the tightening device is installed and before the machine tool is put into operation.

In practice, it often happens that the clamping device has to be replaced with another one, for example a chuck with an arbor with a longer or shorter overall stroke. In this case, it is common to replace the opening/closing cam contrary to regulations or to neglect to adjust the limit switch in accordance with the changed total stroke of the tightening device. Particularly on new machine tools, the clamping cylinder is inaccessibly covered by a cover, so that this operation requires even more care and time.

Furthermore, it is known to provide a code generator in a tightening device that can be mounted on a machine tool, and to assign this code generator to a specific setpoint stroke. This target stroke is compared with the actual stroke value via a comparator. If this comparison detects that the installed tightening device is out of its working stroke, a locking of the machine tool takes place. Because this known device uses a coded tightening device, it necessarily has a special construction and can therefore only be used in future installations of the machine tool. Furthermore, this device has the possibility that an error in transmitting the code may cause an operating position that is outside the original operating range.

The object of the present invention is to improve such a device,
The object is to avoid manual replacement of opening/closing cams or adjustment of limit switches (sensors), and to allow automatic adjustment of the operating stroke of the tightening device, taking into account the necessary additional tightening stroke.

In order to solve this problem, according to the present invention, the opening/closing cam of the opening/closing piece is opened to the opening/closing bar in all opening/closing positions and is immovably fixed to the opening/closing bar, and the sensor is fixed to the opening/closing bar in the direction of movement of the opening/closing bar. The sensor is mounted on a parallel movable reciprocating body, and together with the reciprocating body, the sensor opens and closes the cam along the longitudinal guide of the support housing against the holding force during the movement stroke, which must be done before the start of machining by the machine tool. It can be moved to the end position that defines the respective operating stroke, taking into account additional tightening strokes, and is attached to each reciprocating body and acts automatically when the machine tool is stopped or when the tightening device is replaced. By means of the actuating motor, the sensor together with the reciprocating body can be moved from the zero position to the starting point of the movement stroke.

Thus, according to the invention, the operating range of the installed tightening device is automatically defined on the basis of the travel distance. During the next movement stroke of the tightening device, the reciprocating body holding the sensor is moved to a position corresponding to the entire stroke. In order to ensure the necessary additional tightening stroke in the range of both end positions, the sensor generates a signal that limits the operating range before reaching the end position. In order to eliminate the position caused by the zero travel stroke when the machine tool is stopped or the tightening device is replaced, an actuating motor is provided, which moves the shuttle and therefore the sensor to the zero position of the zero travel stroke. The device according to the invention thus enables reliable detection and monitoring of the operating stroke using the actual full stroke of the tightening device, with simple and trouble-free operating mechanical components.

After stopping the machine tool or replacing the clamping device, the initial movement stroke of the clamping device automatically determines the position of the opening/closing rod corresponding to the working stroke, taking into account the necessary additional tightening strokes. This eliminates the need for manual adjustment of the sensor. In other words, the respective end position of the opening/closing rod is determined only by the movement stroke, since this is done before the start of machining with the machine tool. When the machine tool is shut down or the clamping device is replaced, the mechanically stored positions for the working stroke are automatically erased. Since there is no need for manual adjustment of the sensor, the device according to the invention can also be easily installed on existing machine tools, thus allowing a universal use of the device according to the invention, which significantly increases reliability.

The drawing shows an embodiment of the device according to the invention.

Figures 1 and 2 of the drawings show the main shaft 1 of the machine tool.
, and a tightening device 2 is attached to the front flange of this spindle.
is installed. This tightening device 2 is formed in FIG. 1 by a pawl chuck. In the drawing, a chuck main body 2a and a tightening claw 2b consisting of a master claw and a temporary claw are recognized. The chuck piston 2c that drives the tightening claw 2b is connected to the chuck body 2a.
It is guided so as to be axially movable therein and engages with the master pawl of the clamping pawl 2a via a key transmission.

The construction of the tightening device 2 results in a total stroke H of the tightening device 2, which is marked below the tightening device 2 in FIG.

When clamping a workpiece between the clamping jaws 2b from both the outside and the inside, the chuck piston 2c is inserted between the clamping jaws 2b before the necessary clamping force is generated in order to ensure that the necessary holding force is generated for each machining process. must be avoided from coming to the front or rear end of its entire stroke H. Consideration must always be taken that when the clamping jaw 2b contacts the workpiece, additional steps of the clamping jaw 2b are still possible, since the workpiece may deform and the teeth of the jaw may dig into the workpiece. It won't happen. For this reason, the so-called additional tightening stroke N is
By decreasing from both sides, the working stroke A is obtained.

In order to operate the tightening device 2, a tightening cylinder 3 is attached to the rear flange 1a of the main shaft 1 and rotates together with the main shaft 1, the piston 3a of which is connected via a piston rod 15b and an operating rod 4 to a chuck piston 2c. There is. The clamping cylinder 3 is a double-acting cylinder, for example a hydraulic cylinder, which is supplied with pressure medium via a pressure medium transfer housing 5. The pressure medium transfer housing 5 rotates together with the main shaft 1 and the clamping cylinder 3 and has a shaft formed with a hole leading to the clamping cylinder 3 and a pressure medium supported on this rotating shaft to a pressure medium source (not shown). and a stationary housing with connections.

Via the respective position of the piston 3a in the clamping cylinder 3, the corresponding position of the chuck piston 2c and thus of the clamping pawl 2b is detected. For this purpose, the piston 3a of the clamping cylinder 3 is connected to a switching rod 6, which exits the clamping cylinder 3 and into a pressure medium transfer housing 5.
is guided through the axis of On the free end of this opening/closing rod 6, according to FIG. 3, a closing piece 8 is supported by a ball bearing 7 and, in the illustrated embodiment, is provided with two opening/closing cams 8a and 8b. These opening/closing cams 8a and 8b protruding radially from the opening/closing piece 8 are connected to an axial cutout 9a of the support housing 9.
Since the opening/closing piece 8 is guided inward, it is carried along in the longitudinal direction by the opening/closing rod 6, but is prevented from rotating via its opening/closing cams 8a and 8b. In the illustrated embodiment, the opening and closing rod 6 rotates together with the clamping cylinder 3, which is mounted on the main shaft 1 of the machine tool, so that the use of ball bearings 7 is necessary in this case.

Each opening/closing cam 8a or 8b is a reciprocating body 1.
The sensor 10a or 10b provided at Each of the two reciprocating bodies 11 is guided by the longitudinal guide portion 9b of the support housing 9, and the reciprocating bodies 11
It is movable against the clamping force of a disc spring 12 provided between the head of the screw 13 screwed into the support housing 9 and a washer 14 in contact with the outside of a part of the support housing 9.

After the tightening device 2 shown in the form of a pawl chuck in FIG. Ru. In FIG. 1, below this clamping cylinder 3, the possible total stroke G of the piston rod 3a of the clamping cylinder 3 is drawn, and within this total stroke G is the total stroke H of the clamping device 2.

In this movement stroke of the tightening device 2, the reciprocating body 11 holding the sensors 10a and 10b is moved to a position corresponding to the full stroke H against the tightening force of the disk spring 12. For this purpose, the reciprocating body 11, which is arranged in the figure in the upper part of the support housing 9, is provided with a driving piece 11a, which
1a corresponds to the left end surface of the opening/closing cam 8a, whereas the sliding body 1 provided at the lower part of the support housing 9
1 has a driving piece 11b which cooperates with the right end face of the opening/closing cam 8b.

As can be seen from the left part of FIG. 1, the reciprocating body 1 holding the sensor 10a through the opening/closing rod 6 and the opening/closing piece 8a due to the leftward movement of the piston 3a
1 is moved to the left to a position representing the left end of the entire stroke H. The subsequent rightward movement of the piston 3a causes the reciprocating body 11 holding the sensor 10b to be carried rightward to a position representing the other end of the entire stroke H via the opening/closing cam 8b of the opening/closing piece 8. The initial movement stroke of the tightening device 2 carried out in this way therefore memorizes the position of the opening/closing rod 6, which defines the total stroke H, and thus the corresponding position of the chuck piston 2c.

Two actuating motors are provided in the support housing 9 in order to bring the shuttle 11 into the zero position before each movement stroke defining the total stroke H. Third
In the illustrated embodiment, these actuating motors are each formed by an actuating cylinder 15 that is arranged or constructed in the support housing 9 . Each operating cylinder 15 is provided with an operating piston 15a, the piston rod 15b of which projects from the housing of the operating cylinder 15 and acts on the corresponding reciprocating body 11, via its entraining piece 11a or 11b, the opening/closing piece 8 is Corresponding opening/closing cam 8a or 8b
can be pressed. This pressing is performed by a return spring 15c provided inside the piston rod 15b. This return spring 15c is supported on the one hand by the piston rod 15b and on the other hand by the closing lid 15d which closes the piston space of the actuating cylinder 15. When the pressure medium acting on the actuating piston 15a opposite to the direction of action of the return spring 15c is interrupted, for example when stopping the machine tool or replacing the tightening device 2, the return spring 1
5c comes into play. In this state, the operating pistons 1 of both operating cylinders 15 act in opposite directions.
5a presses both reciprocating bodies 11 against the opening/closing cams 8a and 8b of the opening/closing piece 8, so that the sensors 10a and 10b reliably reach the zero position and the tightening device 2
The new movement stroke of sensors 10a and 10
This zero position prevents starting of the machine tool unless b is transferred to a position defining the total stroke H.

As mentioned above, the two end positions of the entire stroke H of the tightening device 2 are thereby memorized. In order to ensure the necessary additional tightening stroke N in the range of both end positions, the situation shown in FIG. 5 is used. Fifth
In the figure, the chain line drawn on the end face of the sensor 10a configured as a non-contact limit switch indicates its effective opening/closing area. When the opening/closing cam 8a, which can also be seen in FIG. 5, comes within this effective opening/closing area, the necessary opening/closing pulses of the sensor 10a are generated. Between this occurrence of the opening/closing pulse and the actual contact of the opening/closing cam 8a with the engagement piece 11a, there is therefore a desired additional tightening stroke N, which is likewise marked in FIG. The device described above thus makes it possible to start the machine tool only during the working stroke A (FIG. 1), which is the total stroke H minus the two additional tightening strokes N.

The same effect can be obtained by using an electro-mechanical limit switch 16 as shown in FIG. 6 instead of using the contactless limit switch shown in FIG. 5 as the sensor 10a or 10b. The push rod 16a of this limit switch 16 also has an opening/closing cam 8a.
Similarly, it has a rising slope. The lower chain line in FIG. 6 indicates the initial position that the roof-like push rod 16a takes when it does not contact the opening/closing cam 8a. On the other hand, when the push rod 16a is moved to the position shown by the solid line by the opening/closing cam 8a, an opening/closing pulse is generated. Therefore, this opening/closing pulse is generated before the entraining piece 11a of the reciprocating body 11 hits the opening/closing cam 8a. The push rod 16a moves to the upper end position shown by the upper chain line, and the opening/closing cam 8a and the entraining piece 11
When a and a meet each other, no more opening/closing pulses are generated. Thus, in the electro-mechanical limit switch 16, as in the contactless limit switch, the operating stroke A can be obtained by reducing the additional tightening stroke N on both sides of the total stroke H.

Tightening devices 2 each attached to the main shaft 1
After the entire stroke H or the working stroke A has been stored in the above-mentioned manner by the movable sensors 10a and 10b, it is also possible to move the piston 3a of the clamping cylinder 3 in a defined manner within the range of the working stroke A. be. If the piston 3a is outside this stored operating stroke A, the machine tool control prevents the main spindle 1 from starting. Furthermore, if the piston 3a leaves the stored operating stroke A due to unforeseen circumstances, the machine tool will be stopped.

Once the machining process carried out with the pawl chuck according to FIG. 1 has been completed, the pawl chuck according to FIG. 1 can be replaced, for example, by an arbor as shown in FIG. This arbor has a clamping piston 2e which is axially movable within the housing 2d. This axial movement of the clamping piston 2e is caused by the clamping piece 2, which is clamped between the pressure pin 2g and the tension screw 2h, via the slope visible in FIG.
Perform the tightening or loosening movement f.

Under the tightening device 2, which is configured as an arbor in FIG.
The additional tightening stroke N on both sides is reduced. Due to a complete movement cycle of opening and closing the arbor, the entire stroke H1 of the arbor is accounted for by the sensors 10a and 10b. The entire stroke G of the tightening cylinder 3 in Fig. 2
From Figure 2, in which this total stroke H1 is drawn, it can be seen that the total stroke H1 of the arbor is not only smaller than the total stroke H of the previously installed pawl chuck, but is also in a different range of the total stroke G of the piston 3a. I understand that.

By taking into account the additional tightening stroke N, therefore, not only the end position of the opening and closing rod 6 of the entire possible stroke H1 for the arbor is memorized, but also the operating stroke A1. After storing the values of the arbor thus installed, it can be ensured that when operating the machine tool, the piston 3a of the clamping cylinder 3 is now only within the permissible operating stroke A1. A rotary movement of the main shaft 1 is possible only when the piston 3a is within the working stroke A1 set in the arbor.

In order to ensure the zero position of the sensors 10a and 10b not only when the machine tool is stopped, but also when replacing the tightening device 2 attached to the spindle 1 with the pressure medium supply device connected. ,
A contactless limit switch 17 is provided next to the flange of the main shaft 1 and can be kept inactive by the flat rear face of the clamping device 2 to which it is attached. That is, when this tightening device 2 is removed, the limit switch 17 generates a pulse which interrupts the supply of pressure medium to the actuating piston 15a of the actuating cylinder 15 and which, by means of the activated return spring 15c, causes the sensor 10a and 10b is moved to the zero position. At this zero position both sensors 10a and 10
Since b is damped, there is no permissible movement path A or A1, and the movement path A of the installed tightening device 2 is determined by carrying out the movement path and is memorized by the position of the sensors 10a and 10b. Only then can the machine tool be started.
The machine tool can therefore only be started when the operating stroke A or A1 belonging to the installed tightening device 2 is determined, so that incorrect operations and unacceptable operating states of the machine tool and of the installed tightening device 2 are excluded and the installed tightening device 2 The determination of the movement path is simply carried out by carrying out the movement path of the device 2.

[Brief explanation of drawings]

Figure 1 is a vertically sectional side view of the main parts of the double-acting tightening cylinder that operates the chuck and the device that determines its respective operating range, and Figure 2 is the tightening cylinder with an arbor attached instead of the chuck and the operating range determining device. 3 is a sectional view taken along the axis of the operating range determination device in FIGS. 1 and 2, FIG. 4 is a sectional view taken along the cutting line in FIG. 3, and FIG. 6 is an enlarged view of a portion of the apparatus of FIG. 1 to illustrate the additional tightening stroke of a contactless limit switch, and FIG. 6 is a view corresponding to FIG. 5 when an electro-mechanical limit switch is used. 2...Tightening device, 3...Tightening cylinder, 3
a... Tightening piston, 6... Opening/closing rod, 8... Opening/closing piece, 8a, 8b... Opening/closing cam, 9... Support housing, 9b... Vertical guide section, 10a, 10b...
Sensor, 11... Reciprocating body, 15... Operation motor,
A, A1...Operating stroke, N...Additional tightening stroke.

Claims (1)

[Claims] 1. The machine tool has a double-acting tightening cylinder 3 that operates the tightening device 2, and when the tightening cylinder 3 is outside the operation stroke A, A1, the drive device of the machine tool that processes the workpiece The opening/closing rod 6, which is stopped or restrained and is connected to the tightening piston 3a of the tightening cylinder 3, is connected to at least two opening/closing cams 8a, 8.
These opening/closing cams 8 have an opening/closing piece 8 with a
Sensors 10a and 10b are provided corresponding to sensors a and 8b, respectively, and can be operated by these opening/closing cams.
However, in the case where the movement of the opening/closing rod 6 within the predetermined operation strokes A, A1 is monitored in consideration of the additional tightening stroke N, and the opening/closing positions of the sensors 10a, 10b by the opening/closing cams 8a, 8b are variable, the opening/closing piece is The opening/closing cams 8a, 8b of 8 are immovably fixed to the opening/closing rod 6 in all opening/closing positions, and the sensors 10a, 10b are movable in parallel to the moving direction of the opening/closing rod 6. 11, and the sensors 10a and 10b are provided together with the reciprocating body 11.
However, this should be done before the start of machining with the machine tool, so during the movement stroke the longitudinal guide 9 of the support housing 9
along b, the opening/closing cams 8a, 8b resist the holding force.
It is possible to move to the end position that defines the respective operation strokes A and A1 in consideration of the additional tightening stroke N, and is also attached to each reciprocating body 11 to stop the operation of the machine tool or replace the tightening device 2. A complex system for operating a tightening device of a machine tool, characterized in that the sensors 10a, 10b, together with the reciprocating body 11, can be moved from the zero position, which is the base point of the movement stroke, by the operation motor 15, which operates automatically during the operation. A device for determining the operating range of a dynamic tightening cylinder. 2. The reciprocating body 11 has entrainment pieces 11a and 11b,
2. Device according to claim 1, characterized in that during movement the opening and closing cams 8a, 8b abut against the driving piece. 3 The operation motor that acts on the reciprocating body 11 is formed by the operation cylinder 15, and its piston rod 15b
an operating piston 15 acting on the reciprocating body 11 via
Claim 1, characterized in that a is loaded in the direction of action by a return spring 15c and can be moved into the inoperative position by means of a pressure medium against this return spring 15c. Device. 4. Two operating cylinders 15 acting in mutually opposite directions are provided in a support housing 9 equipped with a vertical guide portion 9b for the reciprocating body 11 holding the sensors 10a, 10b, and this support housing 9 simultaneously operates the opening/closing cams 8a, It is characterized in that it is configured as a guide part and a rotation stopper part for the opening/closing piece 8 equipped with the opening/closing piece 8b.
Apparatus according to claim 1. 5. Device according to claim 1, characterized in that the opening/closing cams 8a, 8b are guided in a rotationally fixed manner in an axial cutout 9a of the support housing 9. 6 Additional tightening stroke N is applied to sensors 10a and 10b.
3. The apparatus according to claim 2, wherein the distance is equal to the distance between the operating position of the opening and closing cams 8a and 8b and the position where the opening/closing cams 8a and 8b contact the driving pieces 11a and 11b.