JPH0360618B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an automatic tool change position control method that allows tool changes in a machining center to be performed efficiently in a short time.

(b) Background of the technology Recently, even in machining centers, automatic program input has been developed, which allows operators to easily input machining programs by referring to machining drawings and using input means such as keyboards, without the need for specialized programmers. It has been developed and put into practical use.

(c) Prior Art and Problems Conventionally, when a tool change is commanded in a machining center using this type of automatic program, both the table on which the work is mounted and the spindle on which the tool is mounted are moved and positioned to a predetermined tool change position.
Tools are exchanged by the ATC arm at that location. This is done to prevent interference between the tool, the ATC arm, and the workpiece when exchanging tools with the ATC arm, but the tool exchange position where the table and spindle move depends on the shape of the workpiece. It was designed to have an extremely large dimensional margin so that it could be accommodated.

Therefore, for relatively small workpieces, tools can be exchanged by simply moving the spindle to the tool exchange position in the axial direction of the workpiece (in other words, without moving the table in any way) while remaining in the normal machining position. to,
There was a problem in that tools could not be changed unless the table was moved to a predetermined tool changing position. This means that the time required to move the table to the tool exchange position is longer than the time required for the spindle to reach the tool exchange position, and the more tools are exchanged, the more time is lost due to unnecessary table movement. This means that the entire machining time will be longer.

(d) Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the present invention eliminates wasteful evacuation of the table, eliminates loss time even when the number of tool changes increases, and therefore shortens the overall machining time. , it is an object of the present invention to provide a method for controlling an automatic tool change position in a machining center.

(e) Structure of the Invention That is, the present invention stores tool dimension data of tools used for machining and parameters indicating mechanical positional relationships during automatic tool exchange in a first memory, and also stores input means. The workpiece position data is stored in a second memory through the memory, and when the tool is replaced, the tool dimension data and parameters are read out from the first memory to determine the maximum protrusion amount of each tool and the maximum protrusion amount of the ATC arm. Further, the effective maximum protrusion amount is determined as the maximum value thereof, and the effective clearance amount is determined based on the workpiece position data read from the second memory and the effective maximum protrusion amount, and the determined effective clearance amount is calculated. Based on this, if it is determined that there will be no interference between the machine side and the workpiece being machined when changing tools,
It is configured to issue a command to move only the main spindle in its axial direction to a tool exchange position to perform tool exchange.

(f) Embodiments of the invention Hereinafter, embodiments of the invention will be specifically described based on the drawings.

Fig. 1 is a front view showing an example of a machining center to which the present invention is applied, Fig. 2 is a schematic diagram showing the dimensional relationship between a workpiece on a table, a spindle, and an ATC arm, and Fig. 3 is an automatic tool according to the present invention. FIG. 2 is a block diagram showing an example of a numerical control device for a machining center to which an embodiment of a method for controlling a replacement position is applied.

The machining center 1, as shown in FIG.
It has a body 5, and the body 5 has a table 2 which is movably driven in the directions of arrows A and B and in a horizontal plane perpendicular thereto. A spindle head 3 is provided above the table 2 and is supported by a machine body 5 so as to be movable and driven in the vertical direction in the figure, that is, in the directions of arrows C and D. It is set freely. An ATC arm 7 is provided on the side of the spindle head 3 of the fuselage 5, and the ATC arm 7 is connected to the second
As shown in the figure, an arm 7b having tool gripping portions 7a, 7a formed at both ends is provided so as to be able to protrude in the directions of arrows C and D and to be freely rotatable over a range of 180° in the directions of arrows E and F. The machine body 5 is also provided with a tool magazine 9 that stores a plurality of tools used by the machining center 1 for machining, and is further provided with a numerical control device 10 that controls the machining operations of the machining center 1.

The numerical control device 10, as shown in FIG. 19, the machine control section 20 is connected. A table movement control section 21 and a spindle movement control section 22 are connected to the machine control section 20, a table drive motor 23 is connected to the table movement control section 21, and a spindle drive motor 25 is connected to the spindle movement control section 22.
is connected.

Since the machining center 1 has the above-mentioned configuration, when machining a workpiece, as shown in FIG. from the magazine 9 by a tool transfer device (not shown).
It is transported to the ATC arm 7 and attached to the main shaft 6 by the ATC arm 7. In this state, while rotating the main shaft 6, the spindle head 3 is appropriately moved in directions C and D, which are the axial directions of the main shaft 6, and the table 2
Machining is performed by moving the workpiece together with the workpiece in the A and B directions and in the horizontal direction perpendicular thereto.

While processing in this way, if it becomes necessary to change the tool attached to the spindle 6,
As shown in FIG. 2, the main spindle 6 is moved in the D direction to set the reference surface 6a of the main spindle 6 to a predetermined tool exchange position X1.
, and rotate the ATC arm 7, for example, in the F direction, so that the tool gripping portion 7a on the spindle 6 side is attached to the spindle 6.
The tool 27 to be replaced is engaged with the tool 27 attached to the tool 27 and the tool 27 is gripped. On the other hand, a tool magazine 9 is already attached to the grip part 7a on the opposite side to the side where the tool 27 is gripped.
Since the tool 26 to be used for the next machining that has been transported from the machine is being gripped, the arm 7b is made to protrude in the C direction in this state. Then, the tool 27 mounted on the main spindle 6 is released from engagement with the main spindle 6 and is taken out from the main spindle 6 downward in the figure. Therefore, the arm 7b is rotated by 180 degrees so that the tool 26 to be used for the next machining is opposed to the spindle 6, and the arm 7b is moved back in the D direction to attach the tool 26 to the spindle 6. When the tool 26 is attached to the main shaft 6, the arm 7b is rotated 90° in the E direction and returned to the standby position.

At this time, since there is a workpiece 29 being machined below the main spindle 6 in the figure, the arm 7 of the ATC arm 7
When b moves in the C direction, the tools 26 and 27 held by the arm 7b or the C of the ATC arm 7
It is determined whether or not the projecting portion 7c in the direction interferes with the workpiece 29, and if it is determined that there will be no interference between the workpiece 29 and the tools 26, 27, etc., the workpiece 29, and therefore the table 2, are not touched in any way. Simply move the main shaft 6 without moving it in the A or B direction or in a direction perpendicular thereto.
in the D direction, which is the axial direction of the tool change position
Tools can be replaced by simply moving the tool to position 1.

To be more specific, all machining operations of the machining center 1 are performed by the main control section 1 as shown in FIG.
2 reads a predetermined machining program PRO from the machining program memory 16 and outputs an operation command DC to the machine control unit 20 according to the machining program PRO, thereby controlling the machine control unit 20, the table movement control unit 21, and the spindle. The table drive motor 23, spindle drive motor 25, etc. are controlled and executed in accordance with the machining program PRO via the movement control unit 22 and the like. Tool change is done using the machining program
This is done based on the tool change command TCC that exists in PRO. In other words, tool 2 is
When there are exchange commands TCC 6 and 27, main control unit 1
2 searches the tool file 19 and reads out the tool lengths TL ₁ and TL ₂ of the tool 27 currently mounted on the spindle 6 and the tool 26 to be replaced. The tool file 19 stores the tool length TL for all tools specified in the machining program PRO and therefore used for machining the workpiece 29, so that the tool length TL corresponding to the tool specified in the machining program PRO is stored. The tool length TL is immediately known.

Next, the main control unit 12 searches the parameter memory 17, and calculates the distance L1 from the machine origin ZP to the tool exchange position
The maximum protrusion length L3 of the arm 7b toward the workpiece 29 side is read out. In addition, the main control unit 12 reads from the machining program PRO the distance L4 from the machine origin ZP of the program origin PZP, which is the reference for machining, and the clearance amount CL from the program origin PZP, that is, the workpiece surface 29a, and the clearance amount CL from the program origin PZP, that is, the workpiece surface 29a. Maximum amount of protrusion of each tool in the C direction T ₁ max,
T ₂ max and maximum protrusion amount Amax of ATC arm 7
is calculated using equations (1), (2), and (3).

T ₁ max=L1+L2+TL ₁ ……(1) T ₂ max=L1+L2+TL ₂ ……(2) Amax=L1+L2+L2 ……(3) Next, as the maximum effective overhang amount MAX on the machine side,
Adopt the maximum value of T ₁ max, T ₂ max, Amax,
From that value, determine the effective clearance amount EC using equation (4).

EC=L4-CL-MAC......(4) If the effective clearance amount EC is 0 or more, when changing tools, tools 26, 27,
All of the ATC arms 7 are in a state where they can secure the clearance amount CL for the work 29, that is, the work 2
Since it is determined that there is no interference with the tool 9, the main control section 12 outputs a simple tool change command RTC to the machine control section 20. In addition, the machining program
The distance L4 and clearance amount CL in PRO are input by the operator from the keyboard 15 when creating the machining program PRO, and are stored in the machining program memory 16 as the machining program PRO.

As a result, the machine control section 20 drives the spindle drive motor 25 via the spindle movement control section 22, moves the spindle head 3 in the direction of arrow D, that is, in the axial direction of the spindle 6, and moves the spindle 6 toward the predetermined tool. The table 2 is positioned at the conversion position X1, and the tools 26 and 27 are exchanged by the ATC arm 7 without moving the table 2 in any way, thus maintaining the position where the tool 27 was being processed. When the tool exchange is completed, the main control unit 12 starts a predetermined machining operation using the tool 26 based on the machining program PRO, but since the workpiece 29 on the table 2 has not moved at all since the previous machining with the tool 27. (That is, since the table 2 and the workpiece 29 have not been moved to a tool exchange position far away from the position of the workpiece 29 being machined), the predetermined machining using the tool 26 can be performed immediately.

On the other hand, if the effective clearance amount EC is negative,
When exchanging tools, the tools 26, 27 on the machine side,
Since it is determined that one of the ATC arms 7 is in a state in which it is not possible to secure the clearance amount CL for the workpiece 29, that is, in a state in which interference with the workpiece 29 may occur, the main control unit 12 normally controls the machine control unit 20. Outputs the tool change command TC.

Then, the machine control unit 20 enters a normal tool exchange operation, drives the table 2 in the horizontal direction by the table drive motor 23 via the table movement control unit 21, positions it at a predetermined tool exchange position, and then moves the table 2 to a predetermined tool exchange position. The spindle drive motor 25 is driven via the movement control unit 22 to move the spindle head 3 in the direction of the spindle axis to position the spindle 6 at a predetermined tool changing position X1, and the ATC arm 7 moves the tool 2
6 and 27 are exchanged. In this case,
After the tool is exchanged by the ATC arm 7, the table 2 and the workpiece 29 are moved from the tool exchange position to the position where the machining program PRO is executed again, and subsequent machining is performed.

(g) Effect of the Invention As explained above, according to the present invention, the tool length TL of the tools 26, 27, etc. used for machining is stored in the first memory such as the tool file 19 and the parameter memory 17. Dimensional data, distance L1 from machine origin ZP to tool change position X1, ATC arm 7
The workpiece 2 of the arm 7b, such as the maximum protrusion amount L2 toward the workpiece 29 side and the protrusion part 7c when exchanging tools.
Parameters indicating the mechanical positional relationship during automatic tool exchange, such as the maximum protrusion length L3 to the 9 side, are stored, and via input means such as the keyboard 15,
Machine origin of PZP, which is the program origin that serves as the reference for machining
Distance L4 from ZP, clearance amount CL from program origin PZP, that is, work surface 29a, etc.
The workpiece position data is stored in a second memory such as the machining program memory 16, and when changing tools,
The tool dimension data and parameters are read out from the first memory, the maximum protrusion amounts T ₁ max and T ₂ max of each tool 26 and 27, and the maximum protrusion amount Amax of the ATC arm 7 are calculated, and furthermore, the maximum protrusion amount Amax of the ATC arm 7 is calculated. An effective maximum ejection amount MAX is determined as the maximum value, and an effective clearance amount EC is determined based on the workpiece position data read from the second memory and the effective maximum ejection amount MAX, and based on the determined effective clearance amount EC. When changing tools, if it is determined that there will be no interference between the ATC arm 7, tools 26, 27, etc. on the machine side and the workpiece 29 being machined, move only the main spindle 6 in the direction of its axis. Since the command is given to move the tool to the exchange position X1 and change the tool, the other workpiece 29
The work of retracting the tool to a predetermined tool exchange position relative to the spindle 6 (the table 2 does not move,
This also includes the case where the main shaft portion such as the spindle head 3 moves horizontally relative to the workpiece 29. ), tool change while in the machining position is work 29
Since it is controlled so that it is performed only in cases where it is difficult due to interference with Finished,
A method for controlling an automatic tool change position in a machining center can be provided.

Note that it goes without saying that the first memory and the second memory can be set in the same memory space.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of a machining center to which the present invention is applied, Fig. 2 is a schematic diagram showing the dimensional relationship between a workpiece on a table, a spindle, and an ATC arm, and Fig. 3 is an automatic tool according to the present invention. FIG. 2 is a block diagram showing an example of a numerical control device for a machining center to which an embodiment of a method for controlling a replacement position is applied. 1... Machining center, 6... Spindle, 7...
ATC arm, 15...Input means (keyboard),
16...Second memory (machining program memory),
17...First memory (parameter memory), 1
9...First memory (tool file), 26,2
7...Tool, TL, TL ₁ , TL ₂ ...Tool dimension data, L1...Parameter (distance), L2...Parameter (maximum protrusion amount), L3...Parameter (maximum protrusion length), L4...Work location data (distance),
CL……Work position data (clearance amount),
T ₁ max, T ₂ max, Amax……Maximum protrusion amount,
MAX...Effective maximum overhang amount, EC...Effective clearance amount, X1...Tool exchange position.

Claims (1)

[Claims] 1 Move the spindle with the tool installed in the direction of the axis of the spindle to the predetermined tool change position
In a machining center that performs tool exchange using an arm, tool dimension data of tools used for machining and parameters indicating mechanical positional relationships during automatic tool exchange are stored in a first memory, and through an input means, Store the workpiece position data in a second memory, and when exchanging tools, read tool dimension data and parameters from the first memory to calculate the maximum protrusion amount of each tool and the maximum protrusion amount of the ATC arm, Furthermore, the effective maximum protrusion amount is determined as the maximum value of these, and the effective clearance amount is determined based on the workpiece position data read from the second memory and the effective maximum protrusion amount, and based on the determined effective clearance amount. When changing tools, if it is determined that there will be no interference between the machine side and the workpiece being machined, only the spindle can be changed.
A method for controlling an automatic tool exchange position in a machining center configured to issue a command to move the tool in the axial direction to the tool exchange position and perform the tool exchange.