JPS5950443B2 - Chip cutting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically cutting chips generated during continuous cutting.

In the conventional cutting process, cutting chips are continuously sent out while curling and get stuck in cutting equipment, which always poses a problem when high-speed cutting or continuous unmanned operation is performed.

Furthermore, when using automatic measuring equipment, it has been difficult to solve the problem of protecting the equipment.

For this reason, there are two methods for cutting chips: a method of swinging the tool to give uneven feed, or a method of momentarily stopping the feed of the blade for a short period of time.

However, since these methods are carried out using a regular cutter, they have the disadvantage that the feed pattern becomes uneven and the surface finish deteriorates, significantly reducing the commercial value and prolonging the machining time.

There is also a method of forming long lead cutting grooves on the surface in advance.

In this method, when the machining allowance is relatively large, it is difficult to process the grooves, and the processing time is added, which is not good in terms of efficiency.

Furthermore, there is a method of applying ultrasonic vibration to the cutter.

Although this method produces a clean surface finish, it requires a special, expensive device that generates ultrasonic waves.

Furthermore, there arises the problem of a mounting location for imparting vibration to the blade.

Particularly in the case of a turret type, installation is more difficult, and all three methods have their own problems.

Therefore, the present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a chip cutting method that takes advantage of the characteristics of simultaneous four-axis control of a plurality of tool rests.

That is, machining is performed by applying the normal depth of cut and feed rate using the first tool post.

Then, cut the second turret with a smaller machining allowance than the first turret,
This is a method in which oscillating feed is superimposed on the normal speed, cutting is performed simultaneously with two tool rests, and the thickness of the chips is varied, and the chips are cut dynamically as they are being sent out.

This embodiment will be explained based on the drawings.

In Figure 1, the lathe has a number of
A tool rest 1 and a second tool rest 2 are mounted.

A feed screw 6 is rotated by servo motors 4 and 5 that are controlled and driven by commands from a numerical control device 3 for simultaneous four-axis control.
, 7, the first and second tool rests 1 and 2 are independently fed in the direction of the spindle center line, that is, in the Z-axis direction.

Further, the first, first and second
The second tool rests 1 and 2 are independently fed in the cutting direction into the workpiece, that is, in the X-axis direction.

In this invention, the first turret 1 is used for normal machining, the second turret 2 is used for auxiliary machining, and the two are combined to perform cutting.

The cutting tool A on the first tool rest 1 has a normal cutting depth D1φ−Dφ/
2 and the feed rate Fmm/re.

On the other hand, the cutter B of the second tool rest 2 is given a depth of cut D0φ-D2φ/2 smaller than the depth of cut of the first tool rest, and the depth of cut D2φ-D1φ/2 is applied to the first tool rest 1 in the X-axis direction. 2 offset, and the feed rate is superimposed by giving a feed rate of Δf (t) mm/re, that is, a swing feed, to the feed rate F mm/re of the A cutter.

This will be explained using an example in FIGS. 3 and 4.5. 1A and B cutters are in almost symmetrical positions with respect to the spindle center line, and the relative feed speed of B cutter to A cutter is positive from 0 rotations of the spindle to 2 rotations, and at exactly 2 rotations, the advance of B cutter relative to A cutter is maximum. Therefore, it is negative from 2nd rotation to 4th rotation, but during that time A
The position of the B knife relative to the knife is still in the advance area,
After exactly 4 rotations, the A and B cutters are at the same position in the Z-axis direction.

Furthermore, from 4 to 6 rotations of the main shaft, the relative feed speed of the B cutter to the A cutter becomes negative, and at exactly 6 rotations, the delay of the B cutter to the A cutter becomes maximum, and from 6 to 8 rotations of the main shaft, the relative feed speed is negative. The speed becomes positive and A at exactly 8 rotations,
The B cutter is at the same position in the Z-axis direction.

In this way, one cycle is made up of 0 to 8 rotations of the main shaft, and thereafter this cycle is repeated.

As shown in Figure 6, chips with a width equivalent to the depth of cut of the B cutter are generated when the spindle rotates 0 to 4 times, and when the spindle rotates 4 to 8 times, chips are generated as shown in Figure 6. In other words, chips are cut by cutting or not cutting, while for the A cutter, the main axis is 0~
In the advance range of B cutter with 4 rotations, the total depth of cut of A cutter (DI
φ-Dφ/2)-B cutter depth of cut (DIφ-D2φ/2
), and chips with a width of D1φ-Dφ/2, which corresponds to the total depth of cut of the A knife, are generated in the lag region of the B cutter with 4 to 8 rotations of the spindle. , the chips are automatically cut at the point where the width of the chips changes.

Next, in explaining a block diagram for controlling the first and second tool rests, a diagram for controlling the tool rest of a conventional numerical control device is shown in FIG.

Since this diagram is already well known, no particular explanation will be given.

Figures 8, 9 and 10 showing the first embodiment will be explained.

In this method, a magnification is selected according to the number of output pulses of the spindle pulse generator, and the generator output is converted by this magnification.

The control of the first tool rest 1 having the A cutter is the same as the conventional one.

That is, the pulses from the main shaft pulse generator 31 are counted by the main shaft pulse counter 32a, and the pulses from the main shaft pulse generator 31 are counted by the main shaft pulse counter 32a.
sent to.

On the other hand, one pulse per rotation of the main shaft one-rotation signal generator 34 is also sent to the function generator 33a, and necessary commands are sent to the servo amplifier.

On the other hand, the second tool rest 2 having the B cutter receives the pulses from the main shaft pulse generator, counts the pulses by the main shaft pulse counter 32b, and sends the pulses to the multiplier 35.

This multiplier receives pulses from the spindle one rotation signal generator 34, determines a magnification region and magnification based on the spindle pulse count number, converts the spindle pulses using the determined values, and sends the converted spindle pulses to the function generator 33b.

Next, in FIG. 9 showing the multiplier, the main shaft one revolution signal is input to the one revolution signal counter 36 and counted.

This counter 36 is cleared by a numerical value set by a count number setting device 37 that sets the number of revolutions of the main shaft in one cycle.

The output of this counter 36 is input to a constant selector 38.

On the other hand, the output of the spindle pulse generator is sent to the spindle pulse counter 39.
are input and counted.

The constant selector 38 inputting this count number determines a multiplier for each predetermined range of the count number together with the input from the one revolution signal counter 36, and the multiplier 4 uses this multiplier every moment.
Enter 0.

The output of the spindle pulse counter 32b is multiplied by this magnification and the converted count number is sent to the multiplier generator 33b.

The output of the count number setter 37 is also input to a constant selector 38, which switches the operation of the constant selector, which will be described later, to an operation suitable for the set spindle rotation speed.

Next, in FIG. 10 showing the operation of the constant selector 38,
One rotation pulse of the main shaft is 1000 pulses, and the setter of the count number setting device 37 is turned 8 times, which is one cycle.

Between 0 and 1 rotation of the main shaft, the pulse range is divided as shown in the figure, and the multiplier output is set as a speed increase range from 1.0 to 1.5.

For the next 1 to 2 rotations, increase the magnification to 1.5 to 1 within the same pulse range.
．． Even when the speed is set to 0 and the speed is lowered, it is still in the speed increasing range.

During the next 2 to 3 rotations, the same pulse range is used, and the magnification is 1.0 to 0.
．． 5 and reduce the speed and enter the deceleration area.

During the next 3 to 4 rotations, the same pulse range is used at a magnification of 0.5 to 1.
0, which continues to be the deceleration region.

For the following 4 to 8 rotations, the same pulse range and the magnification is 1.0 to 0.
．． 5.0.5~1.0.1.0~1.5.1・5~1.
0, and one cycle ends with 0 to 8 rotations.

This momentary magnification is multiplied by the main axis pulse number.

Next, a second embodiment will be explained with reference to FIG.

This selects a magnification according to the number of output pulses of the spindle pulse generator, and uses this magnification to increase or decrease the commanded feed speed of the second turret 2 to the same commanded feed speed as the first turret 1. .

In other words, the same command feed rate as that of the first tool post is input to the multiplier 41, and this multiplier converts it into the magnification area and magnification determined by the output of the spindle pulse generator and the output of the spindle one rotation signal generator. The command feed rate is sent to the function generator.

In this case, the multiplier 41 is the same as in FIG. 9, but the multiplier 40
Instead of the output of the main shaft pulse counter which is manually operated,
The same command feed rate as the tool post is input.

As explained in detail above, the feed rate of the main blade is a uniform feed that is commanded, and the machining allowance is changed step by step repeatedly using the auxiliary blade to perform cutting. The machined surface can be cut on a uniform, beautiful surface without compromising the product value.

Furthermore, since cutting is performed simultaneously with two ordered blades, there is no need for pre-processing time and effort.

Also, by simply changing the depth of cut and feed rate commands, it can handle a wide range of conditions from rough machining to finishing machining.

Furthermore, it has many features such as being able to handle not only the Z-axis direction but also all machining directions such as the X-axis direction.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a numerically controlled lathe with four-axis control. FIG. 2 is a diagram showing the relationship between the main knife and the auxiliary knife. Fig. 3.4 shows the relationship between the main cutting tool and the auxiliary cutting tool with respect to the rotation of the main shaft, Fig. 3 shows the relationship in feed rate, and Fig. 4 shows the relationship in position. Figure 5 is an explanatory diagram of the double-edged tool during cutting, where A indicates the advance area and mouth indicates the lag area. FIG. 6 is a diagram showing the shapes of chips generated by the main cutting tool and the auxiliary cutting tool. FIG. 7 is a control diagram of the turret of a conventional numerical control device. FIG. 8 is a control diagram of the characteristic part of this invention. FIG. 9 is a block diagram of the multiplier shown in FIG. 8. FIG. 10 is an explanatory diagram of the operation of the constant selector shown in FIG. 9. FIG. 11 is a control diagram of a characteristic part of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...First tool post, 2...Second tool post, 3...Numerical controller, 31...Spindle pulse generator, 32... ...Spindle pulse counter,
33...Function generator, 34...Main axis 1
Rotation signal generator, 35... Multiplier, 36...
...One revolution signal counter, 37...Count number setter, 38...Constant selector, 39...
...Spindle pulse counter.

Claims (1)

[Claims] 1. In a numerically controlled lathe having at least two turrets, each of which is independently controlled at the same time, the first turret is given a normal depth of cut and cutting feed rate, and the second turret is given a normal depth of cut and cutting feed rate. gives a depth of cut that is smaller than the depth of cut of the first tool post and a cutting feed rate that increases or decreases by a certain amount with respect to the cutting feed rate of the first tool post,
A chip cutting method characterized in that the feed state of the second tool post alternately repeats an advance region and a lag region with respect to the first tool post. 2 The method of giving the second tool post a cutting feed rate that increases or decreases by a certain amount with respect to the cutting feed rate of the first tool post is to select a multiplication factor according to the number of output pulses of the spindle pulse generator in the numerical control device. 2. The chip cutting method according to claim 1, wherein the number of output pulses of the spindle pulse generator is multiplied by this magnification, converted, and sent to a function generator. 3 The method of giving the cutting feed rate of the second tool post that increases or decreases by a certain amount with respect to the cutting feed rate of the first tool post is to select a multiplication factor according to the number of output pulses of the spindle pulse generator in the numerical control device. 2. The chip cutting method according to claim 1, wherein the commanded feed rate is multiplied by the same magnification as that of the first tool post, converted, and sent to the function generator.