JP2585768B2 - Cutting feed setting device for machine tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a cutting feed setting device for a machine tool applied to an NC control machine tool having an automatic machining function.

(Prior art) In general, when a workpiece such as a cast part having a variation in shape and dimensions is chucked and rotated on a chuck or a table of a machine tool such as an NC lathe, the shape and dimension of the workpiece are rotated. Of the workpiece, the rotational trajectory of the outer shape of the workpiece increases considerably in comparison with the designed dimension of the workpiece due to the variation of the workpiece and the centering runout allowed when the workpiece is chucked. The degree of increase in the dimension is not constant, but varies depending on the individual workpiece. When cutting is performed on such a workpiece, the cutting tool is moved to a cutting feed start set position in a rapid traverse state, and is moved at a cutting feed speed from here to cut the workpiece. However, the cutting feed start setting position is conventionally set to a position corresponding to the maximum dimension of the rotation trajectory of the outer shape that varies depending on the individual workpiece.

FIG. 4 and FIG. 5 are views showing the movement of the cutting tool at the time of the conventional cutting, which will be described below.
The cylindrical workpiece 1 having a non-circular outer shape is chucked by a chuck device (not shown) so as to rotate about a center line a of the inner peripheral portion 2. The rough cutting tool 3 is moved at a rapid traverse to the cutting feed start set position A as shown in FIG.
From here, the path shown by the broken line 4 is moved at the cutting feed speed to the cutting feed end setting position B, and the end face of the workpiece 1 is rough-worked. The roughing cutting tool 5 is moved at a rapid traverse to a cutting feed start setting position C as shown in FIG. 4, and is moved from there to a path indicated by a broken line 6 at a cutting feed speed to a cutting feed end setting position D. Thus, the inner surface of the annular ridge 7 on the inner periphery of the workpiece 1 is rough-machined. After this, the cutting tool 8 for finishing
Is moved from the cutting feed start setting position A, which is the same as in the case of rough machining, to the cutting feed end setting position B at the cutting feed speed at the cutting feed speed, and the end face of the workpiece 1 is moved. Finish processing. Then, as shown in FIG. 5, the cutting tool 10 for finishing is moved from the cutting feed start set position C to a broken line 11.
Is moved to the cutting feed end setting position D at the cutting feed speed to finish the inner surface of the step portion 7 on the inner periphery of the workpiece 1. In this case, even if the cutting tool 3, 5 is moved at the cutting feed speed from the cutting feed start set position A, C, the cutting start execution position A ', C' where the cutting of the workpiece 1 is actually started is reached. Until then, the cutting tools 3, 5 exhibit a so-called air cut state in which the workpiece 1 is not cut at all.

(Problems to be solved by the invention) By the way, in the movement of the conventional cutting tool described above,
The cutting feed start setting positions A and C are positions corresponding to the maximum size of the rotation trajectory of the outer shape that varies depending on the individual workpiece as described above. The same position is set in any of the cases where finishing is performed using the cutting tool 8. For this reason, depending on the individual workpieces, the cutting feed start setting positions A and C may be located substantially before the cutting start execution positions A 'and C'. In such a case, when finishing,
Since the cutting feed speed is low, wasteful time without cutting the workpiece in the air-cut state will take a considerably long time, and the ratio of the wasteful time in the entire machining time will increase, There is a situation that this wasted time increases the processing cost.

Therefore, an object of the present invention is to provide a cutting feed setting device for a machine tool that performs finishing after roughing, thereby shortening the time required for machining and reducing the machining cost. .

[Configuration of the Invention] (Means for Solving the Problems) The present invention provides a method for cutting after one of a workpiece and a cutting tool chucked by a chuck device is moved at a rapid feed to a cutting feed start set position with respect to the other. In a machine tool that performs cutting by being moved at a feed rate, and performs finishing after roughing, the cutting tool for roughing of the workpiece causes vibration generated in the cutting tool during the roughing. A detecting device for detecting and detecting a cutting start execution position of the rough machining is provided, a cutting start execution position at the time of rough machining detected by the detection device is stored, and a finishing process is performed based on the stored cutting start execution position. A control device is sometimes provided which corrects the cutting feed start setting position of the cutting tool for finishing processing so as to be closer to the workpiece than during rough processing.

(Operation) According to the above-described means, the cutting feed start set position of the finishing cutting tool is corrected so as to be closer to the workpiece than during roughing at the time of finishing. In addition, the air cut time during finishing processing can be reduced as much as possible for individual workpieces with different centering runouts, and the time required for processing can be shortened, and the processing cost can be reduced. it can.

(Embodiment) An embodiment in which the present invention is applied to a vertical NC automatic lathe will be described below with reference to FIGS.

Reference numeral 20 denotes a cylindrical workpiece having a non-circular outer diameter, which is chucked by a chuck device 21 fixed to a main shaft (not shown) so as to rotate about the center line b of the inner peripheral portion 22. An annular ridge 23 is formed on the inner peripheral portion 22. 24 is a tool post, which has a cutting tool 25 for roughing
Is installed. Although not shown in detail, the tool rest 24 includes a cutting tool 26 for rough machining shown in FIG. 2 and cutting tools 27 and 28 as cutting tools for finishing machining shown in FIG. Each is provided in a replaceable state. Reference numeral 29 denotes a vibration sensor attached to the tool post 24, and the output of the vibration sensor is supplied to the detection device 30. Reference numeral 31 denotes a control device, which is provided with an NC control device and the like for controlling the rotation of the spindle and the movement of the tool post 24, and exchanges signals between the control device and the detection device 30. I have.

Next, the operation of the above configuration will be described. First, the workpiece 20 chucked by the chuck device 21 by the rotation of the spindle
Then, the roughing cutting tool 25 is moved at a rapid feed from the standby position to the cutting feed start setting position A, and from there, is moved in the direction indicated by the broken line 32 in the direction of the arrow 33 at the cutting feed speed. Then, when the cutting tool 25 is moved in the direction of the arrow 33 and passes the cutting start execution position A ′ for actually cutting the work 20, the work 20 is cut. Since the vibration is transmitted to the tool post 24, the vibration is detected by the vibration sensor 29 and the output is detected by the detecting device.
Give to 30. Then, the detection device 30 gives an output signal to the control device 31 at the position where the cutting tool 25 starts to vibrate, that is, the cutting start execution position A '. When this signal is given, the control device 31 calculates the coordinates of the position of the cutting tool 25 at that time. Remember. When the cutting tool 25 is moved in the direction of the arrow 33 and approaches the cutting end execution position B ′, the cutting tool 25 intermittently separates from the workpiece 20, and after passing the cutting end execution position B ′, it completely separates from the workpiece 20. In this state, the vibration generated in the cutting tool 25 is changed from continuous to intermittent, and finally the vibration disappears. Then, the detection device 30 determines that the cutting tool 25 has passed the cutting end execution position B ′ when there is no output from the vibration sensor 29 even if the main shaft rotates a predetermined time, and gives a signal to the control device 31. When a signal is given, the control device 31 further sets the tool post 24 from the cutting feed speed to a rapid feed state at a position where the main shaft rotates a predetermined time and the tool 25 has a predetermined gap from the workpiece 20, and the tool 25
To the standby position.

Next, the roughing cutting tool 26 is moved from the standby position to the cutting feed start setting position C by rapid traverse, and from there, is moved in the direction indicated by the broken line 34 in the direction of arrow 35 at the cutting feed speed. Then, when the cutting tool 26 is moved in the direction of the arrow 34 and passes the cutting start execution position C 'where the cutting section 23 of the workpiece 20 is actually cut, vibration generated in the cutting tool 26 during cutting is performed in the same manner as described above. Is detected by the vibration sensor 29 provided on the tool post 24 and is given to the detecting device 30. Therefore, the output signal is controlled at the position where the cutting tool 26 starts to vibrate, that is, the cutting start execution position C '.
When this signal is given, the controller 31 stores the coordinates of the position of the byte 26 at that time. Byte 26 is arrow 35
In the direction and passes cutting end execution position D '
When the vibration of 26 is eliminated, similarly to the above, the control device 31 further rotates the main shaft by a predetermined amount and the cutting tool moves the tool post 24 at a position where the cutting tool 26 has a predetermined gap from the ridge 23 of the workpiece 20. , And the byte 26 is returned to the standby position.

Subsequently, the finishing cutting tool 27 is moved from the standby position to the cutting feed start set position A ″ by rapid traverse, from which the path indicated by the broken line 32 is moved in the direction of the arrow 33 at the cutting feed speed, and the work piece is moved. 20 is started, the cutting feed start set position A ″ is based on the cutting feed start execution position A ′ stored in the control device 31 and considering only the following speed of the operation, the outer shape of the workpiece 20. Is set as close as possible. In this way, the finishing operation is performed while the cutting tool 27 is moved in the direction of the arrow 33, and the cutting tool passes the cutting end execution position B '.
When the vibration of 27 is eliminated, the control device 31 further rotates the spindle a predetermined time and the cutting tool 27
The tool post 24 is rapidly moved from the cutting feed speed to a position where a predetermined gap exists from 20 to return the cutting tool 27 to the standby position.

Next, the cutting tool 28 is moved from the standby position to the cutting feed start setting position C ″ by rapid traverse, and from here the cutting feed speed is moved in the direction indicated by the broken line 34 in the direction of the arrow 35 to cut the workpiece 20. Cutting is started, and the cutting feed start set position C ″ is determined based on the cutting feed start execution position C ′ stored in the control device 31 in the same manner as described above, and considering only the operation follow-up speed. Is set to a position as close as possible to the outer shape of the ridge 23. In this way, when the finishing operation is performed while the cutting tool 28 is moved in the direction of the arrow 35 and the vibration of the cutting tool 28 disappears after the cutting end execution position D ', the control device 31 Further, the main shaft is rotated by a predetermined amount, and the tool post 24 is rapidly fed from the cutting feed speed at a position where the cutting tool 28 has a predetermined gap from the ridge 23 of the workpiece 20 to return the cutting tool 28 to the standby position.

As described above, in the present embodiment, the cutting feed start set positions A ″, C ″ at the time of finish machining are changed to the cutting feed start set positions A, at the time of rough machining.
Since the correction is made so as to be closer to the workpiece 20 as compared with C, the time of the air cut at the start of the finishing processing can be shortened as much as possible in comparison with the related art.

Further, in the above-described embodiment, in both cases of the roughing and the finishing, by detecting the vibration of the cutting tools 25 to 28, the cutting tools 25 to 28 are moved to the cutting end execution position B ′.
From the position slightly past D ', in the fast forward state,
28 is returned to the standby position, so that the cutting feed end set position B,
Compared to the conventional method in which the cutting feed is performed up to D, the time of the air cut after passing the cutting end execution position B'D 'can be reduced as much as possible in both the roughing time and the finishing processing.

In the above-described embodiment, the case where the present invention is applied to an NC lathe has been described, but the same applies to other machine tools such as an NC milling machine in which a table chucking a workpiece moves and displaces with respect to a cutting tool. Can be implemented.

[Effects of the Invention] As is clear from the above description, the present invention minimizes the time of air cutting during finishing for individual workpieces having variations in shape and size and different centering runouts. Thus, there is an excellent effect that the time required for processing can be shortened and the processing cost can be reduced.

[Brief description of the drawings]

1 to 3 show one embodiment of the present invention. FIG. 1 is a perspective view of a main part, FIGS. 2 and 3 are operation explanatory views, and FIGS. 4 and 5 are conventional figures. FIG. In the drawings, 20 is a workpiece, 21 is a chuck device, 25 to 28 are cutting tools (cutting tools), 29 is a vibration sensor, 30 is a detection device, and 31 is a control device.

Claims (1)

(57) [Claims] 1. A method in which one of a workpiece and a cutting tool chucked by a chuck device is moved by a rapid feed to a cutting feed start set position with respect to the other, and then moved at a cutting feed speed to perform cutting. In a machine tool that performs finish machining after rough machining, a cutting tool for rough machining of the workpiece detects vibration generated in the cutting tool during the rough machining and detects a cutting start execution position of the rough machining. A detection device is provided, and a cutting start execution position at the time of rough machining detected by the detection device is stored. Based on the stored cutting start execution position, a cutting feed start setting position of a cutting tool for finishing machining at the time of finishing machining. A cutting device for a machine tool, comprising a control device for correcting the position of the workpiece to be closer to the workpiece than during rough machining.