JPS6119539A - Controlling method and device for machine tool - Google Patents

Abstract

PURPOSE:To efficiently perform an automatic work by a comparatively simple means by arranging a control means for a machine tool to repeat a cutting work after a pattern approximate to the model-pattern of an efficient cutting work carried out first. CONSTITUTION:In a drilling machine 1, after a standard cutting operation is carried out for a specific material, a operation pattern is made, for example, by plotting the number of revolution per unit time of a workpiece relative to that of cutting tool on the axis of ordinate, and a cutting time on the axis of abscissa which are measured during working proces, and then it is desgnated as a model-pattern A. The specific workpiece assigned for repeated cutting process is first fixed on the table of a drilling machine 1, and is machined with specific drills at the number of revolution and tool feed selected for standard working efficiency. This working pattern is stored as a model-pattern 3 in a memory. Consequently an automatic work can be efficiently performed by a comparatively simple means.

Description

Detailed Description of the Invention: a. Industrial Application Field The present invention relates to a control method and a control device for a machine tool, and more specifically, to proper cutting of a machine tool using the relative rotation of a workpiece and a cutting tool. The present invention relates to a control method and device for maintaining efficiency.

b. Prior art In order to perform highly efficient machining with conventional automatic machine tools, there is a method of controlling tool feed by detecting the drive torque of a rotary drive device such as an electric motor, and controlling by detecting the current consumption of the electric motor. How to
There was a control method using elastic wave propagation (E).

C9 Problems to be Solved by the Invention The above-mentioned conventional control methods and control devices that utilize torque detection or current consumption have poor accuracy, and other methods have disadvantages in that the detection devices are complicated and expensive. It is.

Means for Solving the d9 Problem The present invention repeatedly creates a model pattern of changes in the relative rotation speeds of the workpiece and cutting tool from the start of machining to the completion of machining, in order to efficiently obtain a product through a specific cutting process, and then The same cutting process is performed under the direction 1 cutting conditions. The number of revolutions during machining is compared with the corresponding value of the model pattern, and if the difference remains outside the allowable range for a certain period of time, the difference is controlled to fall within the allowable range. The present invention solves the disadvantages of conventional methods and devices by performing cutting by controlling at least one of the relative rotational speed and feed of a workpiece and a cutting tool.

e. Embodiment As shown in FIG. 1, an embodiment of the present invention is to carry out standard cutting processing on a specific material, and to determine the relative unit of the workpiece and the cutting tool during the processing. Model pattern A was defined as the number of revolutions per hour on the vertical axis and the time course of the cutting process on the horizontal axis.

In this case, since the means for changing the number of rotations per unit time is frequency conversion of the voltage of the motor power source, it is sometimes called the rotation frequency.

FIG. 1 shows an example of the drilling machine 1 shown in the first part of FIG.

First, fix a specific workpiece to be repeatedly cut on the table of drilling machine 1, use a specific drill, select the rotation speed and tool feed to standard work efficiency, and model it without machinability. It is stored in the storage device as pattern 3.

FIG. 1 shows a model pattern 3 regarding the number of rotations of a tool, and FIG. 4 shows an example of a model pattern 7 regarding back pressure with respect to the feed oil pressure of a tool.

Figure 1 shows the rotation of the drill 9 from the time it is driven until it stops. Not in contact.

When the drill 9 enters the workpiece, the curve descends, and the rotational speed indicated by C is maintained while the entire end face of the drill 9 is being cut.

When the tip of the drill 9 penetrates the workpiece, the cutting area decreases and the curve rises from point D and reaches point E.

After that, the rotation will return to zero by pulling the drill back and turning off the power.

If the range of constant speed rotation mentioned above is called the monitoring zone, then the decrease in rotation speed is mainly due to an increase in cutting force, and in addition to the presence of local high-hardness parts of the workpiece, This is usually caused by chipping.

For example, 5% in rotation speed above and below the model pattern 3 described above.
There are two allowable rotational speed ranges P and R for higher and lower speeds.

The model pattern 3 mentioned above is a model pattern in which the optimal work is carried out by considering various angles such as accuracy, machining surface, and tool life when machining a specific material to a specific dimension, and is a standard for subsequent repeated machining. This is the result.

A storage device 5 in which the model pattern 3 described above is shown in FIG.
Then, the data is stored in the RAM 11 shown in FIG. 3, and repeated production is started.

The broken line in FIG. 1 is an example of actual cutting, and the power is transmitted to the detection device 19 from the motor shaft 13, spindle shaft 15, power transmission section 17, etc. shown in FIG.

In FIG. 3, pulses are transmitted from the encoder 21, limit switch 23, etc. to the counter 25.

In the example shown by the broken line in Figure 1, even though cutting is being performed at the rotation speed of model pattern 3, the cutting edge of the tool has deteriorated, or the tool encounters a hard part of the workpiece and rotates due to large resistance. This indicates that the number is decreasing.

Also, the reason why the rotation speed is low even before the monitoring section is thought to be due to oil leaks in the bearings, etc.

In the monitoring section shown in FIG. 1, the rotational speed is sampled in each of many small sections, and is transmitted to the comparator 27 in FIG. 2 and the CPU (central processing unit) 29 in FIG. The current state of the rotation speed is known as shown in the figure.

At point E in FIG. 1, the low-speed permissible rotational speed range R was finally exceeded, and after another fixed period of time, point G was reached.

In this poem, the controller W31 shown in Fig. 2 and the solid processing device 29 shown in Fig. 3 increase the rotational speed of the drill 9 using the frequency conversion transformer 35 shown in Fig. 3 using the instruction method from the ROM 33. , the flow control valve 37 is closed to increase the back pressure.

Alternatively, both may be operated at the same time and controlled to approach model pattern 3. - The purpose of waiting until after the above-mentioned one fixed period of time has elapsed is to distinguish whether or not it is a momentary abnormality when a partially high hardness part of the workpiece is encountered.

In addition, if the cutting efficiency does not improve even if the above-mentioned measures to lead to high efficiency cutting are taken and the cutting rate worsens and progresses to H, the tool is damaged, so the control unit 31 and the central processing unit 29
immediately issues a command to stop cutting, the tool leaves the workpiece, and rotation stops.

What is shown in Fig. 4 is a system that controls the fluid that sends the tool to the workpiece and the back pressure that acts, which is a descendant of the rotation speed control shown in Fig. 1. Two pressures are shown.

If a back pressure B1 lower than the first allowable lower limit pressure is generated during cutting, the back pressure is controlled to be increased so as to approach the model pattern 7 after one fixed period of time, leading to B2. A+ and A2 mean damage such as chipping of the tool, and even though it led to a return to the model pattern 7 described above, the back pressure decreased to below the second allowable lower limit pressure, so the work was immediately ordered to stop. Indicates when to do so.

In the embodiments of the present invention described in more than 10 functions, when the same machining is repeatedly performed on a specific workpiece, the most efficient machining is first performed in terms of machining accuracy, machining efficiency, tool life, etc. to create a model pattern of tool rotation speed and feed pressure.

This is stored in a storage device, and actual machining is performed, and the tool rotation speed and feed pressure are sampled every moment and compared with the model pattern. If the upper and lower permissible limits are exceeded, the control method and device are operated to control the rotational speed and feed pressure so that the pattern approaches the model pattern after a certain period of time.

0. Effects of the Invention The embodiments of the present invention repeatedly perform cutting that approximates the model pattern of the first highly efficient cutting operation using a relatively simple method and device, thereby achieving highly efficient automated work. It was.

Additionally, it also helps improve productivity by detecting tool damage and taking action to stop work.

Machine tools include grinding machines.

This grinding tool is a type of cutting tool in which irregularly shaped abrasive grains are dispersed and fixed in a binder, and a large number of fine abrasive grains perform cutting operations one after another.

Therefore, it is clear that the technical idea of the present invention extends to the grinding machine, and other design changes can be easily made without departing from the technical idea of the present invention.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a model pattern regarding the number of rotations of a tool. FIG. 2 is a block diagram showing the operation of the control method. FIG. 3 is a block diagram showing the connection of control devices. FIG. 4 is an explanatory diagram of a model pattern related to hydraulic pressure for feeding a tool. (Explanation of symbols representing main parts of the drawings) 1...Drilling machine 3...Model pattern 7...Back pressure model pattern 19...Detection device 27...Comparison device 29...
-Central processing unit 31...Control device 35...Transformer using frequency conversion. 1st vlJ Katama 2nd figure 3rd figure Minko 9- 21 7i Tokapuku Okiashi 25 Capital ETC Nojin! Shakui/Risaki
1=, 1l RAM CPLI F? , C)hSiOE)7
4th figure size of 0 - Soil

Claims (2)

[Claims] (1) When performing a specific cutting process repeatedly using relative rotation between the workpiece and the cutting tool, create a model pattern of the change in rotation speed from the start of the process to completion, and then repeat the same cutting process under the same cutting conditions. Compare the rotation speed during machining with the corresponding value of the model pattern above, and if the difference is outside the allowable range and a certain period of time has passed, change the workpiece so that the difference falls within the allowable range. 1. A method for controlling a machine tool, comprising: controlling at least one of the relative rotational speed and feed of a cutting tool and a cutting tool to perform cutting close to a model pattern. (2) A rotational speed detection device, a storage device for a rotational speed model pattern, a comparison device for both rotational speeds, and a drive rotational speed and relative feed so that the subsequent machining rotational speed is within the allowable rotational speed range. A control device for a machine tool, characterized by being provided with a control device.