JPS61209852A - Adaptive control device for machine tool - Google Patents

Abstract

PURPOSE:To make the unattended continuous operation of a machine tool possible by controlling tool relief and its return to an original position to reduce a load according to output given by a detecting means of the case in which adaptive control becomes impossible and a tool position storage means. CONSTITUTION:The cutting horsepower 19 of a main motor 1 detected by a detector 2 is compared with a target horsepower 20 in a cutting speed computing section 11, and when it is reduced to a horsepower corresponding to the minimum set value of feed speed, but does not decrease to the target horsepower 20, adaptive control is detected as impossibility, and a tool relief and return control section 13 stops therefore the feed of a motor 15 through a tool position control section 18. At the same time, the information 22 of preset tool position indicated by a tool position detecting section 17 is keept in a machining position storage section 12. Nextly, the control section 13 controls a motor 16 to make the tool to clear a fixed distance alpha, and then causes the tool to cut a part being in front of the final point of the cleared distance alpha. When that cutting work has been completed, the tool is returned to the starting point of the cleared distance alpha kept in the strage section 12 to continue the last lap cutting as far as the distance alpha. Thus the unattended continuous operation of a machine tool can be easily realized.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention can detect overload when machining a workpiece with a machine tool such as a drill or milling machine, and can continue machining at an optimal load value. The present invention relates to an adaptive control device.

<Prior Art> Conventionally, as an adaptive control device for a machine tool, as shown in FIG.
, a cutting speed calculation section 4 to which the detection output is supplied and a set value from the target value setting device 3 for adaptive control, and a speed control section 6 that controls the speed of the feed electric motor I15 according to the output. There are some that are equipped with. The machine A8 that cuts the workpiece 7 receives its cutting power from the main electric motor 411 via the power transmission section 9, and the tool support connected to the drive shaft 10 is moved by the feed motor 5, so that It moves in the cutting direction as shown by S.゛During the cutting process of the workpiece 7, the cutting power by the tool 8 is detected by the detector 2 detecting the current or power of 1ml of the main electric motor connected to the power transmission section 9, and a target value setting device is set for each tool. The cutting speed is calculated by the cutting speed calculation unit 4 so as to obtain the optimum load value set in step 3, and based on this, the speed of the feed motor 5 is controlled by a signal from the speed control unit 6. If the cutting area increases depending on the shape of the object 7, cutting cannot be performed at the optimum load value, making it difficult to continue adaptively controlled cutting. In other words, if the shape of the workpiece 7 has many convex parts and the cutting area is extremely large, the feed rate will be close to zero, and if the lower limit of the feed rate is set with the target setter 3, the applied control will exceed the optimum load value. becomes impossible.

<Problems to be solved by the invention> The present invention has been made in view of the above-mentioned points, and it is possible to continue processing without stopping the machine and perform adaptive control operation even if adaptive control becomes impossible. The purpose of the present invention is to provide an adaptive control device for a machine tool that enables the following.

<Means for Solving the Problems> In order to achieve the above object, an adaptive control device for a machine tool according to the present invention includes means for detecting when adaptive control becomes impossible, means for storing tool position, The present invention is characterized by comprising means for controlling escape and return of the tool to the old position in order to reduce the load in accordance with the outputs from the detection means and the storage means.

<Example> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an adaptive control and overload detection device for a machine tool according to an embodiment of the present invention, and FIGS. A specific example of tool operation and movement progress to reduce the load and continue machining will be shown.

In the following explanation, overload detection devices used during cutting of machine tools, such as overload detection devices for main motors and feed motors, and spindle torque detection devices, are one of the functions of adaptive control, so these devices will not be used. What is included will be described as an adaptive control device.

As shown in FIG. 1, the device of this embodiment includes a current (power) detector 2. In addition to being equipped with an adaptive control target value setting device 3, a cutting speed calculation section 11 serves as a means for detecting when adaptive control becomes impossible, and a machining position storage section 12 serves as a means for storing tool positions.
A tool retraction control section 13 is added as a means for controlling the retraction and return of the tool, and a feed motor control section 14, a feed motor 15 for the cutting direction. The structure includes a feed motor 16 for the cutting direction, a tool position detection section 17, and a tool position control section 18.

The cutting speed calculation unit 11 receives a cutting horsepower 1 from the detector 2.
9 is given, information about a target horsepower 20 is given from the adaptive control target value setter 3, and the cutting speed calculation section 11 gives a speed command 21 to the feed motor speed control section 14. The tool return control section 13 controls the feed motors 15 and 18 via the tool position control section 18 in response to signals from the cutting speed calculation section 11 and the machining position storage section 12. As will be described later, when the adaptive control becomes impossible, the tool is released to the position where the optimum load value is achieved, but the degree to which the tool is released is determined in advance by the tool escape return control unit 13.
is set to . Further, the machining position storage section 12 is provided with tool position information 22 from the tool position detection section 17.

Detection of the inability to adaptively control is performed by the cutting speed calculation unit 11. As shown in Fig. 2, when the tool 8 cuts the workpiece 7 from position A to position B, the lower limit of the feed rate is reached at position B during the cutting movement, and the load value of the spindle further increases. When it is detected that adaptive control is not possible due to exceeding the optimum load value, as shown in the figure, machining A8 is released by an amount α to reduce the cutting area, and cutting is always performed at the optimum load value determined for each tool. Therefore, when the adaptive control is not possible as described in , the feed of the tool 8 is first stopped, the tool 8 is picked at the tool release position 23 to the release position 24, and when the pick is completed, the feed is executed to the feed position before the pick. , when it reaches that feed position, it returns to the machining start point again, and the tool 8
Return to the position before picking and start machining again.

That is, during adaptive control, the cutting horsepower can be known by detecting the current or power of the main electric motor ml with the detector 2, but the cutting horsepower 1 detected by the detector 2
9 is compared with the target horsepower 20 set in advance by the adaptive control target value setter 3 in the cutting speed calculation unit 11, and if the cutting horsepower 19 is higher than the target horsepower 20, the cutting horsepower 18 is increased in order to reduce the feed rate. If the horsepower is less than the target horsepower 20, a feed speed command is calculated to increase the feed speed, and a speed command 21 is given to the speed control unit 14, thereby increasing the feed motor 15.
change the speed of In this way, adaptive control is performed.

During cutting while performing such control, if the cutting horsepower 18 does not reach the target horsepower 20 even if the feed rate is lowered to the minimum feed rate set by the adaptive control target value setter 3, this is calculated by the cutting speed calculation unit 11. It is detected and the signal is sent to the tool escape return control section 13. In the above-described case, when the tool retraction control section 13 receives the detection signal from the cutting speed calculation section 11, it first sends an escort signal to the tool position control section 18 to stop the feeding of the feed motor 15. That is, as described above, when adaptive control is impossible, the tool 8 is moved to the escape position 24.
In order to pick until the point, the feed of the tool 8 is first stopped. At the same time, position information 22 (machining start position, machining end position) of the tool 8 currently being machined detected by the tool position detection section 17 is stored in the machining position storage section 12 .

In this way, after stopping the feed of the tool 8 and storing the position of the tool 8 in the machining position storage section 12, the tool escape return control section 13 causes the tool 8 to escape by a distance α as shown in FIG. This reduces the depth of cut and reduces the load. Since the value of α is set in advance in the machine JLA return control unit 13, the above-mentioned release operation is performed by controlling the feed motor 1B through the tool position control unit 18 based on the value of the tool 8. Explaining the path of movement with reference to FIG. 3, the tool 8 travels from the machining start position 25 through the path 2B to the tool escape position 23, and then further through the path 27 to reach the tool escape position 24.

Thereafter, the tool JiL8 cuts the front part in the cutting direction S shown in FIG. Continue machining only. That is, to explain with reference to FIG. 3, after passing through the route 27, the route 28.
Route 29. The machining end position 32 is reached in the order of the tool escape return operation, path 30 and path 31.

In this way, according to the apparatus of the embodiment, when the feed rate falls below the set value, the cutting area is reduced by releasing the tool 8 by the amount α, as shown in FIG. The workpiece 7 can be cut with the optimum load value. Some workpieces have shapes that have many convex parts and an extremely large cutting area, but even if adaptive control is not possible during cutting of such workpieces, Even if a situation arises,
As described above, by automatically reducing the depth of cut, it is possible to reduce the load and continue machining, and in the adaptive control device of the machine tool, the depth of cut of the tool 8 is automatically reduced to continue adaptive control cutting. be able to. Moreover, this can be done without stopping the machine tool. That is, by providing a function to release the tool JL8 to the position where the optimum load value is obtained when adaptive control becomes impossible, a function to memorize the old position of the tool 8, and a function to return the tool 8 to the previous position from the position from which it was released. , it becomes possible to perform adaptive control operation without stopping the machine, and therefore unmanned continuous operation can be easily realized, the function of adaptive control can be improved, and it can be made easier to use.

Note that the present invention can be applied not only to the drills and milling machines described above, but also to turning machines, die engraving machines, and other machine tools.

<Effects of the Invention> As described above, according to the adaptive control operation of a machine tool according to the present invention, when adaptive control becomes impossible, the load is automatically reduced and machining can be performed continuously at a predetermined load value. Therefore, adaptive control operation can be performed without stopping one machine, and unmanned continuous operation can be easily realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a control device for a machine tool according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of the operation of a tool by the same device, and FIG. An explanatory diagram showing the order of operations, FIG. 4 is a configuration diagram showing a conventional adaptive control device for a machine tool. In the drawing, l...main electric motor. 2... Current (power) detector, 3... Adaptive control target value setter. 7... Workpiece, 8... Tool, +1... Cutting speed calculation section, 12... Machining position storage section. 13... Tool escape return control unit, 15, 18... Feeding motor, 18... Tool position control unit, 24... Tool escape position.

Claims (1)

[Claims] In an adaptive control device for a machine tool, a means for detecting a case where adaptive control becomes impossible, a means for storing a tool position,
An adaptive control device comprising means for controlling escape and return of the tool to its old position in order to reduce the load in accordance with the outputs from the detection means and storage means.