JPS6148722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing method using a numerically controlled lathe.

A common turret configuration for numerically controlled lathes is a single turret head on a crossfeed.
In this case, in order to simplify the creation of the machining program, the cutting edge position of the tool held in the turret head must be at a constant distance from the turret rotation center and within one plane perpendicular to the rotation center line. In many cases, consideration is given to This need not be explained, but the position of the cutting edge will not change even if the tool is changed by the indexing operation of the turret, so the machining program can be created in a fixed coordinate system without changing the coordinate point of the cutting edge. This is because it can be done.

On the other hand, in response to demands such as shortening machining time and simplifying the turret structure, for example, two turret heads are installed on the cross feed table and used alternately to shorten tool change time. Numerical control lathes that aim to reduce costs by arranging multiple tool stands along the feed direction of the cross feed table and using the feed movement to change tools, eliminating the turret indexing mechanism, etc. There are also quite a few.

However, in all numerically controlled lathes of this type, tools are changed by moving the cross feed table, so in one fixed coordinate system, the cutting edge coordinate point changes every time the tool is changed, and the workpiece changes. The positional relationship of the cutting edge of the tool is complicated, and in some cases, the mounting direction of the tool may be reversed, and the cutting direction may be reversed, so creating a machining program has the disadvantage of being extremely troublesome. Ta.

The present invention provides a machining method that eliminates these drawbacks and makes it possible to extremely easily create a machining program for a numerically controlled lathe having a pair of tool stands facing each other across the spindle centerline. The purpose is to

The present invention will be described in detail below. Fig. 1 shows an example of a numerically controlled lathe in which the machining method according to the present invention is effective. 1 is a bed, 2 is a headstock mounted on the bed 1, 3 is rotatably supported by the headstock 2 and rotates while gripping the workpiece; 4 is slidably installed over a pair of parallel guide bars 5 supported by the bed 1; A longitudinal feed 6 is a transverse feed 7 that is movable along a cross slide 4a formed on the longitudinal feed 4 perpendicular to the spindle center line.
Reference numerals a and 7b are a pair of turret heads which are provided on the transverse feed table 6 and are opposed to each other across the center line of the main spindle 3. Reference numerals 8a and 8b are tools, such as bits, provided on the turret heads 7a and 7b respectively, and 9 is a main shaft. This is a steady rest placed on the center line of 3 and fixed to the longitudinal feed base 4.

In this numerically controlled lathe, a rod-shaped material held by a main shaft 3 is fed out from a steady rest 9 to give it rotation.
A pair of turret heads 7a and 7b are advanced alternately to perform machining using a tool such as a cutting tool 8a and 8b. While machining is being performed with one tool, the other turret head performs an indexing operation and is used next. This is intended to shorten tool exchange time by selecting and waiting for a tool to be used and then changing the tool by moving the cross feed table 6.

2, 3, and 4 are explanatory diagrams showing the positional relationship between the spindle 3 and the cutting tools 8a and 8b.
The distance between the cutting edge position of a and the cutting edge position of the cutting tool 8b is set to a predetermined value a,
Therefore, if the cutting edge of the cutting tool 8a is located at an arbitrary distance b from the center of the main shaft 3, the cutting edge of the cutting tool 8b is located at a point B, which is a distance (a-b) from the center of the main shaft 3.

Here, in order to simplify the following explanation, we will ignore the feed in the longitudinal direction and focus only on the feed in the radial direction. The forward and backward movement direction with respect to the center is called the X-axis coordinate, and its zero point is placed at the center of the main shaft 3, and the direction in which the cutting tool 8a approaches the main shaft 3, that is, its advancing direction (rightward direction in Figs. 3 and 4) is It is assumed that the direction is the negative direction of the X-axis coordinate.

According to this, the retracting direction of the cutting tool 8a is the positive direction of the X-axis coordinate, and conversely, the advancing direction of the cutting tool 8b is the positive direction, and the retracting direction is the negative direction.

When turning with this numerically controlled lathe, for example, the cutting tool 8a is
Assuming that a cylinder with a diameter of 2c is cut by cutting a cylinder having a diameter of 2c by moving it forward from the point to a point C having a distance of C from the center of the spindle 3, and then retracting it to point A again to finish its use, the well-known method According to the radius specification method using an absolute value command, the movement command directly indicates the X coordinate value of the point to be moved, in this case, X c ,
Just program it as X b . However, if you subsequently want to cut a cylinder with a diameter of 2d using the cutting tool 8b, cut it from point B to d from the center of the main shaft 3.
It is necessary to move the cutting tool 8a further from point A in the positive direction if this movement command is programmed using the conventional method.
It is necessary to give a command to move the distance (a-b-d) between points B and D. That is, in this case, if the X coordinate value of the point to be moved is programmed as , X d , the cutting tool 8a will move from point A to point D, and cutting with the cutting tool 8b will not be possible in both cases.
Therefore, here, the movement command is (a-b-
d)+b=(a-d),
(a-d) to move the cutting tool 8a from point A to point E, and by moving the cross feed table at that time, the cutting tool 8b must be sent from point B to point D. Needless to say, this is extremely troublesome as the program must be programmed while separately performing numerical calculations, coordinate direction conversion, etc.

Therefore, as shown in the model in Fig. 4, when the cutting tool 8a is advanced from point A to point C and then retracted to point A, when trying to advance the cutting tool 8b from point B to point D, Using a specific command code, for example, the G code, the current coordinate value of point A can be changed from X b to
-(a-b) . This is the same as moving the principal axis 3 a distance a distance in the positive direction of the X-axis coordinate and placing an imaginary principal axis 3' whose center is at a distance in the positive direction (a-b) from point A. It is the meaning. That is, from now on, the X-axis coordinate is reset from the coordinate system with the zero point at the center of the principal axis 3 to a new coordinate system with the zero point at the center of the imaginary principal axis 3',
The movement command also follows this new coordinate system.
According to this, the relationship between the position A of the cutting tool 8a in the new coordinate system and the imaginary main shaft 3' is the same as the relationship between the position B of the cutting tool 8b in the old coordinate system and the actual main shaft 3. Therefore, in order to advance the cutting tool 8b from point B to point D, it is sufficient to move the cutting tool 8a from point A to point E in the new coordinate system. The movement command for that is
-d , but if you compare this command value with the command value when using the above-mentioned cutting tool 8a, for example, when cutting a cylinder with a diameter of 2c, the radius value c
was commanded as a positive value, but here, in order to cut a cylinder with a diameter of 2d, the radius value must be commanded as a negative value. This requires the programmer to separately reverse the sign of the command value, that is, convert the coordinate direction, and the burden cannot be completely alleviated. Therefore, the specific command code mentioned above,
For example, if the G code is used to convert the current coordinate value and at the same time reverse the sign of all subsequent movement command values, the program will always execute the same program as X d , regardless of byte exchange. This makes it possible to do so.

The program created in this way is different from the program for a general numerically controlled lathe with a single turret head mentioned above, except that a specific command code is inserted.
Everything else is exactly the same, making it easy to create a machining program.

Of course, in order to actually perform machining using this machining program, it is necessary to convert the current coordinate values and reverse the positive/negative sign by internal processing of the numerical control device. The value is b=
If we specify a/2, -(a-b)=-b,
Conversion of the current coordinate values only requires reversing the positive and negative signs. In this case, the coordinate system setting function using the G code command seen on the numerical control device and the mirror image function using the G code or M code command can be used together. It can be easily implemented.

As described above, according to the present invention, it is possible to create a machining program for a numerically controlled lathe having a pair of tool stands in exactly the same way as for a general numerically controlled lathe having a single turret head. This eliminates the need for the programmer to perform numerical calculations, which not only shortens the time required for programming, but also has the great effect of minimizing programming errors.

[Brief explanation of the drawing]

1 is a perspective view showing an example of a numerically controlled lathe in which the machining method according to the present invention is effective; FIG. 2 is an explanatory view showing the positional relationship between the spindle and the tool in FIG. 1;
FIG. 4 is an explanatory diagram showing a model of the positional relationship between the spindle and the tool. 3...Main shaft, 6...Transverse feed table, 7a, 7b...
Turret head, 8a, 8b... part-time job.

Claims (1)

[Claims] 1. A main shaft that grips a workpiece and rotates by power, and a pair of tools that are installed on a cross-feed table movable in a direction perpendicular to the center line of the main shaft and that face each other across the center line of the main shaft. A tool held on each of the tool stands such that the distance between the cutting edges becomes a predetermined value a along the direction of movement of the traversing table is moved in the direction toward the center line of the spindle. In a numerically controlled lathe that alternately uses the advancing direction of the tool and its opposite direction as the retracting direction of each tool, use one tool so that its cutting edge is in the retracting direction from the center line of the spindle. When finishing at a point at an arbitrary distance b towards the other end and then starting to use the other tool, the current point of the cutting edge position is -(a-b) using a predetermined command code on the machining program. ), as well as reversing the positive and negative signs of the movement command values for the traversing table that will be commanded thereafter, so that the cutting edge can be adjusted when changing from one tool to another. A processing method for a numerically controlled lathe, characterized in that processing is performed by compensating for positional fluctuations and reversal of the advance direction.