JPH09262742A - Method and device for feed control of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the working time by starting the cutting feed without waiting for a working tool to reach the approach point. SOLUTION: A machine tool in which the fast feeding is performed toward the approach point 5 away by the prescribed approach quantity in the cutting feed direction from the working position of a work 2, and the cutting feed is performed within the plane orthogonal to the cutting feed direction, is provided with a stage to operate the approach time when a working tool 1 reaches from the approach point 5 to the surface of the work through the cutting feed, a stage to operate the position of the working tool at the time before the approach time from the time point when the working tool reaches the approach point 5 through the fast feed, i.e., the cutting feed starting position 7, and a stage to start the cutting feed at the time point when the working tool during the fast feed reaches the cutting feed starting position 7.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to numerical control (hereinafter referred to as N
The present invention relates to a feed control method and device for a machine tool that controls fast feed and cutting feed in an NC machine tool controlled by a device.

[0002]

2. Description of the Related Art When a machine tool is used to continuously perform drilling at a plurality of hole drilling positions, the drill tool must be moved from the current position to the next hole drilling position by rapid traverse. The control of this movement was performed as shown in FIG. The cutting feed direction of the drill tool 1 is the Z-axis direction, and rapid feed is performed in the X-axis direction orthogonal to the Z-axis direction. The rapid feed is started from the rapid feed start point 3, and the drill tool 1 is accelerated and moved toward the approach point 5. At the intermediate point 4, the deceleration of the rapid movement of the drill tool 1 is started, and while decelerating smoothly, it is checked whether or not the approach point 5 is within a predetermined distance (in-position width). When the position of the drill tool 1 reaches within the in-position width, the Z-axis cutting feed is started toward the machining start point 6 of the workpiece 2. The in-position width is usually preset as a constant of about 30 pulses (corresponding to a feed amount of 30 μm) in terms of the number of movement command pulses of the NC device.

[0003]

The machine tool is required to have an improved operating rate, and the adoption of the linear motor significantly increases the maximum value of the rapid feed rate. However, as the maximum value of the fast-forward speed increases, the ratio of the acceleration time until reaching the maximum value and the deceleration time from the maximum value relatively increases. In particular, when the acceleration and deceleration are smoothly changed so that a large inertial force does not act on the movable member, the acceleration time and the deceleration time become long.

FIG. 3 is a graph in which the spindle head of the machine tool and the table are actually moved relative to each other and the speed thereof is measured. The machine tool model is a vertical machining center VK45 manufactured by Hitachi Seiki Co., Ltd., which measures the rapid feed of the table in the horizontal X-axis direction. The dotted line in FIG. 3 represents the movement command value, and as shown in the figure, the movement command is sent to accelerate up to half of the total movement amount, decelerate thereafter, and stop when reaching a predetermined position. The actual speed changes as shown by the solid line due to the inertia of the moving part. Although there is a delay at the start of movement, the moving speed at the time of stop changes exponentially, so it takes a considerably long time to almost stop and reach the in-position width. With conventional feed control,
In this way, a long waiting time is generated when decelerating and stopping, which causes an increase in machining time by the machine tool. Particularly, in the case of repetitive machining such as continuously drilling a large number of holes, the cumulative waiting time has a great influence on the machining time.

Therefore, an object of the present invention is to provide a machine tool feed control method and apparatus capable of starting the cutting feed without waiting for the machining tool to reach the approach point and shortening the machining time. And

[0006]

In order to achieve the above object, a feed control method for a machine tool according to the present invention is arranged in a plane orthogonal to a cutting feed direction from a machining position of a workpiece to a cutting feed direction. In a machine tool that performs rapid feed toward an approach point that is a predetermined distance away from the approach point, and then performs cutting feed, the step of calculating the approach time from the approach point until the machining tool almost reaches the surface of the workpiece by cutting feed. And the step of calculating the position of the machining tool at the time point before the approach time from the time when the machining tool reaches the approach point by rapid feed, that is, the cutting feed start position, and the machining tool during fast feed reaches the cutting feed start position. And the step of starting the cutting feed at the time.

Further, in the above machine tool feed control method, the machine tool can repeatedly perform machining on a plurality of machining locations.

In the above machine tool feed control method, the machine tool can perform drilling on a plurality of holes.

The machine tool feed control apparatus of the present invention performs rapid feed toward an approach point that is away from the machining position of the workpiece in the cutting feed direction by a predetermined approach amount in a plane orthogonal to the cutting feed direction. A feed control device for a machine tool that performs cutting feed and performs cutting feed, and an approach time calculation means that calculates the approach time until the machining tool almost reaches the surface of the workpiece by cutting feed At the time when the tool reaches the approach feed point, the cutting feed start position calculation means for calculating the position of the machining tool at the time before the approach time, that is, the cutting feed start position, and the time when the machining tool reaches the cutting feed start position And a control means for starting the cutting feed.

Further, in the above-described machine tool feed control device, the machine tool can repeatedly perform machining on a plurality of machining points.

Further, in the above-described machine tool feed control device, the machine tool is capable of performing drilling on a plurality of holes.

Further, in the above-mentioned machine tool feed control device, the feed control device is constituted by a numerical control device, and the cutting feed start position calculating means calculates the number of feed pulses from the feed start position to the approach point. It is preferable that the apparatus has an in-position width storage means for storing the number of feed pulses as an in-position width, and the control means starts cutting feed by the in-position width.

In the above feed control method and device, "fast feed" includes not only a narrow sense of fast feed, but also one in which the cutting feed moving speed is set to a high speed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a feed control method in a machine tool of the present invention. The cutting feed direction of the drill tool 1 is the Z-axis direction, and rapid feed is performed in the X-axis direction orthogonal to the Z-axis direction. As in the conventional case of FIG. 2, the rapid feed is started from the rapid feed start point 3 and the drill tool 1 is accelerated and moved toward the approach point 5. The deceleration of the rapid movement of the drill tool 1 is started at the intermediate point 4, and the deceleration is smoothly performed toward the approach point 5.

Here, the time required for the drill tool 1 to reach the machining start point 6 from the approach point 5 by cutting feed, that is, the approach time, is calculated in advance. Furthermore, the position of the drill tool 1 at the time point before the approach time from the time when the drill tool 1 reaches the approach point 5 by the rapid feed, that is, the cutting feed start position 7 is calculated in advance. Then, the in-position width is set so that the end point of the in-position width coincides with the cutting feed start position 7.

Then, by checking whether or not the drill tool 1 is within the in-position width with respect to the approach point 5, it can be determined that the position of the drill tool 1 has reached the cutting feed start position 7. Thereby, the cutting feed of the drill tool 1 in the Z-axis direction is started. The in-position width is not a constant as in the conventional case, but is automatically set by the NC machining program in accordance with the calculation result of the cutting feed start position 7.

From the cutting feed start position 7, the drill tool 1 performs a curvilinear motion as shown in FIG. 1 by combining the final part of the deceleration motion of the rapid feed in the X axis direction and the cutting feed motion in the Z axis direction. become. When the drill tool 1 reaches the processing start point 6, the velocity component in the fast-forward X-axis direction becomes just zero, so that it does not move in the X-axis direction during processing. When the feed control is performed in this manner, the machining time is shortened by the approach time as compared with the conventional case as shown in FIG. Although the end point of the distance when the approach time is calculated is the machining start point 6 here, the end point may be set slightly before the machining start point 6 for safety.

FIG. 4 is a block diagram showing the construction of the machine tool feed control device of the present invention. The feed control device is realized by the NC device 10. The storage means 11 of the NC device 10 is for storing the NC processing program and data, and is composed of a semiconductor storage element or the like. The NC command interpretation / execution unit 15 interprets and executes the NC command stored in the storage unit 11 block by block, and sends a control pulse to an external control motor drive circuit. Further, the NC command interpretation / execution means 15 is inputted with position information of an external moving member which is being controlled.

The approach time calculating means 12 is a distance from the approach point 5 to the machining start point 6, that is, an approach amount Z [mm] and a cutting feed rate F [mm / mi] in the Z-axis direction.
n] is a means for calculating the approach time t [msec]. For example, t is calculated by the following empirical formula.

T = (Z + 0.000621F−0.024) /0.00001667F Formula 1 Formula 1 is obtained experimentally for the vertical machining center VK45 described above, and the mass of the moving body for other machine tools as well. Applicable if each constant determined by the time constant during acceleration / deceleration is experimentally determined. The approach time t calculated by Equation 1 is the approach time calculation means 1
2 is output to the cutting feed start position calculation means 13. The cutting feed start position calculation means 13 obtains the in-position width P [number of pulses] representing the cutting feed start position 7 from the approach time t by an empirical formula such as the following formula.

P = 2.614 · exp (0.027t) Equation 2 “exp” in Equation 2 is an exponential function. Formula 2 is also experimentally obtained for the movement of the vertical machining center VK45 in the X-axis direction, and each constant may be experimentally determined to be applied to other machine tools. The in-position width P calculated by Expression 2 is output to the in-position width storage means 14 and stored therein. The NC instruction interpretation / execution means 15
When the confirmation of the in-position width is designated by a command in the NC machining program, the moving member reaches within the in-position width from the position information of the moving member and the in-position width stored in the in-position width storage means 14. It is determined whether or not it is reached, and when it is reached, the next block of the NC machining program is executed.

As the NC machining program, for example, the following commands are stored in the storage means 11.

Main program N1 G65 Z2.0 F955 P1234; N2 G91 G00 X150.0; N3 G01 Z-50.0; ... Subprogram O1234; N1 Macro statement of expression 1 (calculation result of expression 1 is variable # 500
N2 Macro statement of Expression 2 (calculation result of Expression 2 is variable # 501
N3 G10 L50; N4 N1827 R # 501; N5 G11; N6 M99; The first N1, N2, etc. in each line represent a sequence number. Main program sequence number N1 line (block)
G65 is a macro call command of the custom macro program, and the program number 12 of the program including the block in which the expression 1 and the expression 2 are created in the macro program format.
34 (O1234 subprogram) is called and executed. Further, the values of F and Z designated in the line of this macro call command are passed as an argument to the subprogram (custom macro program) 1234 and are assigned to the variables F and Z of Expression 1. That is, "Z2.0" of the sequence number N1 of the main program is 2.0 in the variable Z.
The numerical value of “F955” is assigned to the variable F by the numerical value of 955.

Then, the approach time t is calculated from the values of the approach amount Z and the cutting feed speed F by the sequence number N1 of the sub program (custom macro program), and the sequence number N2 of the sub program (custom macro program) 1234 is calculated. Is set by the macro so that the in-position width P is calculated by and stored in the variable # 501. That is, the approach time calculation means 12 and the cutting feed start position calculation means 13
Is realized by the subprogram (custom macro program) of program number 1234 which is called and executed by the macro call command G65.

To give concrete numerical values, the approach amount Z =
2.0 [mm], cutting feed rate F = 955 [mm / mi
n], the approach time t = 160.834 [ms
ec], in-position width P = 201 [pulse] (0.
(Equivalent to 201 mm) is calculated, and the numerical value 201 is set in the variable # 501. Although the end point of the distance when the approach time t is calculated is the machining start point 6 here, for safety, the end point may be set slightly before the machining start point 6 by a small amount. That is, the approach amount Z may be set to a value smaller than the actual value by a predetermined amount.

"G10 L50" of the block of sequence number N3 of the subprogram is a programmable parameter input command and is a command to set the data of variable # 501 in the storage area N1827 by executing the block of N4 in the next line. . The storage area N1827 is a storage area in the parameter memory for storing the in-position width, and the in-position width storage means 14 is realized by the storage area N1827. This command
The numerical value 201 is also set in the storage area N1827. G11 of the block N5 of the subprogram represents the end of the parameter input mode, and M99 of the block N6 represents the end of the subprogram.

G91 of the block of the sequence number N2 of the main program is a designation that the subsequent movement command designates coordinates by the relative position. "G00 X150.
“0” is 15 in the X-axis direction relative to the current position by fast-forwarding.
This is an instruction to move by 0.0 mm. At the end of this move command, the in-position width is confirmed and the next block is executed. Numerical value 20 in the in-position width storage means 14
Since 1 is set, approach points 5 to 201
At the position (cutting feed start position 7) before the pulse (0.201 mm), execution of the next block N3 is started.

[G01 Z-50.
0 "is -50.% Relative to the Z-axis direction at the cutting feed rate F.
This is an instruction to move 0 mm. Therefore, from the cutting feed start position 7, the drill tool 1 performs a curvilinear motion as shown in FIG. 1 by combining the rapid feed movement for 201 pulses in the X-axis direction and the cutting feed motion in the Z-axis direction. When such feed control is performed, the cutting feed is started earlier by the approach time t as compared with the conventional control shown in FIG. 2, so that the machining time is shortened accordingly.

When a plurality of holes are continuously machined, the machining time is shortened by the approach time t × the number of repetitions, and the shortening effect is increased accordingly. Further, such control can be easily performed by calling a macro like the N1 block of the main program. Since the function of checking the in-position width is provided as standard equipment in a general NC device, it is not necessary to add any special hardware other than defining a custom macro program such as the sub-program O1234.

The same applies when the fast-forward is performed in the Y-axis direction instead of the X-axis direction. However, when the rapid traverse speed, the time constant, etc. are different between the X-axis and the Y-axis, each constant in the equation 2 must be changed to the constant in the Y-axis direction. In that case, in the N4 block of the subprogram, "N1827 P
a R # 501; ”, the axis number may be designated. That is, P1 for the X-axis and P1 for the Y-axis.
By setting 2, the numerical data can be set in the storage area for each axis of the storage area N1827. It can also be applied to the case where combined rapid traverse of the X axis and the Y axis is performed. Further, in order to perform the calculation of Expression 1 and Expression 2 at high speed, various values of Z, F, and t may be calculated in advance, and the calculation result may be stored as a numerical table. Furthermore, the in-position width setting data is
A command for returning to the initial setting data may be programmed and returned to the initial setting data when the drilling process is completed.

In this embodiment, the case where the drilling is carried out has been taken as an example, but the effect of shortening the working time is large even in other repeated workings such as end milling and tapping.
In addition, the processing alone has the effect of shortening the processing time. Also,
As when using a linear motor as the feed mechanism,
The effect is particularly great when the rapid feed speed is high, but an ordinary servomotor or a feed mechanism using a ball screw mechanism is also effective. In the above description, fast forward is performed by the NC command G0.
Although it has been set to 0, the “fast-forward” in the present invention includes not only the fast-forwarding of NC command G00 but also the fast-moving moving speed of cutting feed such as G01.

[0032]

Since the present invention is configured as described above, it has the following effects.

The processing time can be shortened by the approach time, and the processing efficiency is improved. In the case of repeated processing, the processing efficiency is particularly improved.

The feed control can be easily performed by executing the subprogram according to the macro call command in the NC machining program. Also, the approach time can be shortened simply by giving the approach amount and cutting feed rate,
The feed control method can be very flexible.

Since it can be realized by using the in-position width confirmation function of the existing general NC device, no new hardware is required and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a feed control method in a machine tool of the present invention.

FIG. 2 is a diagram showing an outline of a feed control method in a conventional machine tool.

FIG. 3 is a graph in which the spindle head of a machine tool and a table are moved relative to each other and the speed thereof is measured.

FIG. 4 is a block diagram showing a configuration of a feed control device for a machine tool of the present invention.

[Explanation of symbols]

 1 ... drill tool 2 ... workpiece 3 ... rapid feed start point 4 ... intermediate point 5 ... approach point 6 ... machining start point 7 ... cutting feed start position 10 ... NC device 11 ... storage means 12 ... approach time calculation means 13 ... cutting feed Start position calculation means 14 ... In-position width storage means 15 ... NC instruction interpretation execution means

Claims (7)

[Claims] 1. A rapid feed is carried out toward an approach point (5) which is a predetermined approach distance away from a machining position of a workpiece (2) in a plane orthogonal to a cutting feed direction, and further. In a machine tool for cutting feed, a step of calculating an approach time from the approach point (5) to almost reaching the surface of the workpiece (2) by the cutting feed, and the machining by fast feed Calculating the position of the machining tool (1), that is, the cutting feed start position (7) at the time point before the approach time from the time when the tool (1) reaches the approach point (5); And a step of starting cutting feed when the machining tool (1) reaches the cutting feed start position (7). 2. The feed control method for a machine tool according to claim 1, wherein the machine tool repeatedly performs machining on a plurality of machining points. 3. The feed control method for a machine tool according to claim 1, wherein the machine tool performs a drilling process on a plurality of holes. 4. Fast-forwarding is performed toward an approach point (5), which is a predetermined approach distance away from the machining position of the workpiece (2) in a plane orthogonal to the direction of cutting feed, in the cutting feed direction. A feed control device for a machine tool that performs cutting feed, which is an approach for calculating an approach time from the approach point (5) until the machining tool (1) almost reaches the surface of the workpiece (2) by cutting feed. A time calculation means (12), and the position of the machining tool (1) at the time point before the approach time from the time when the machining tool (1) reaches the approach point (5) by rapid feed, that is, the cutting feed start position Cutting feed start position calculating means (13) for calculating (7), and control means (1) for starting cutting feed when the machining tool (1) reaches the cutting feed start position (7). ) And feed control device for a machine tool having a. 5. The feed control device for a machine tool according to claim 4, wherein the machine tool repeatedly performs machining on a plurality of machining points. 6. The feed control device for a machine tool according to claim 4, wherein the machine tool performs a drilling process on a plurality of holes. 7. The feed control device for a machine tool according to claim 4, wherein the feed control device is constituted by a numerical controller (10), and the cutting feed start position calculating means is provided. (13) calculates the number of feed pulses from the cutting feed start position (7) to the approach point (5), and the in-position width storage means (14) stores the number of feed pulses as an in-position width. A feed control device for a machine tool, wherein the control means (15) starts cutting feed according to the in-position width.