JPH04365539A - Machine tool - Google Patents

Abstract

PURPOSE:To provide a machine tool capable of reducing a working time by reducing time for moving a tool during the process of work. CONSTITUTION:A closed loop 11 to which a dc power supply is serially connected is formed by the contact between a cutting tool 4 and an object 1 to be cut. To the closed loop 11 is connected a controller 13 for controlling a feeder 8 through a conductive sensor 12. Thus, a time immediately after the cutting tool 4 is separated from the object 1 to be cut after the object 1 to be cut is machined can be regarded as a completion point of feed for work.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool for machining a workpiece using a tool such as a cutting tool or a grindstone.

0002

2. Description of the Related Art Conventionally, in numerically controlled machine tools, after a tool is rapidly fed by a feeder and approaches a workpiece, the tool moves at a relatively low machining feed rate while cutting the workpiece. In order to machine a workpiece and after machining, the tool is fast-forwarded again and retreated to move away from the workpiece, the control device is programmed in advance with the start and end points of the machining feed, in addition to the machining dimensions of the workpiece by the tool. is memorized. At the beginning of machining, the control device operates a feed device such as a motor to rapidly advance the tool to bring the workpiece to the starting point, and then the control device operates the feed device to increase the machining feed rate. The tool that is fed at this point contacts the workpiece to machine the workpiece, and then, when the tool reaches the end point, the tool retreats in rapid traverse and returns to the initial position, reducing the machining time of the workpiece. We are trying to make this happen.

0003

In the prior art described above, the start and end points of the machining feed are set with a margin called so-called air cut. This is due to variations in the dimensions of the workpiece, variations in the mounting position of the tool, etc. If there is no margin (air cut) on the starting point side, the mounting position of the workpiece or the tool is abnormal. In this case, the tool collides with the workpiece at high speed and the tool,
This not only damages the workpiece but also has an adverse effect on the machine tool itself, and if there is no allowance (air cut) on the end point side, unmachined parts will be left on the workpiece. Therefore, since the start and end points of the machining feed are set with a margin, the time it takes for the tool to contact the workpiece from the start point and start machining, and the time it takes for the tool to separate from the workpiece. There is a problem that it takes a long time to reach the end point, and as a result, it takes a long time to process the workpiece. There is also the problem that if the air cut distance is incorrectly set during initial setting or tool replacement, the tool and non-cutting object collide during rapid traverse, which adversely affects not only the tool and the non-cutting object but also the machine tool itself.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a machine tool which can solve the above-mentioned problems and shorten the time required to move a tool during machining, thereby shortening the machining time of a workpiece.

[0005]

Means for Solving the Problems In order to achieve the above object, the machine tool of the present invention has a machine tool in which a tool is rapidly fed by a feeding device to approach a workpiece, and while the tool is moving at a machining feed rate, In a machine tool in which the tool retreats after processing a workpiece, the tool is formed of a conductive member,
A closed loop is formed by contact between the tool and the workpiece, and a control device for the feeding device is connected to this closed loop.

[0006]

[Operation] With the above structure, the tool is fed and starts machining the workpiece, and the closed loop is closed. At the end of machining, when the tool separates from the workpiece, the closed loop opens, and the control device rapidly feeds the tool via the feed device to shorten the return machining time.

[0007]

Embodiment Next, a first embodiment of the present invention will be described with reference to FIG. A metal workpiece 1 is held in a metal chuck 3 that is rotated by a rotary drive device 2 such as a motor, and a cutting tool 4, which is a tool for processing the workpiece 1, has a chip 6 at the tip of a holder 5. This bit 4 is fixed to a metal mounting base 7, and this mounting base 7 can be reciprocated in parallel to the rotation axis 9 of the chuck 3 by a feeding device 8 such as a motor. , can move back and forth in opposition to the rotation axis 9. The cutting tool 4 is made of a conductive member, and the contact between the cutting tool 4 and the workpiece 1 causes a DC power supply 10 to be activated.
A closed loop 11 is formed by connecting the two in series. One end of this closed loop 11 is connected to the chuck 3 side, and the other end is connected to the mounting base 7. Said closed loop 1
1 has an energization sensor 12 interposed therein, and this energization sensor 12 is connected to a control device 13 for controlling the feeding device 8. In addition, 16 in the figure is a cutting fluid supplied to the cutting tool 4 and the workpiece 1 during machining. Further, the solid line arrow indicated by A in the figure represents the portion where the cutting tool 4 is rapidly fed, and the broken line arrow shown by B in the drawing represents the portion where the cutting tool 4 is fed for processing.

Next, the operation of the above structure will be explained. After attaching the workpiece 1 to the chuck 3 in advance, when the chuck 3 is driven to rotate and the feeder 8 is activated, the mounting base 7 on which the cutting tool 4 is fixed is rapidly fed parallel to the rotation axis 9 toward the workpiece 1 side. Be moved. When the cutting tool 4 approaches the workpiece 1, the mounting base 7 starts moving at the machining speed leaving a predetermined air cutting distance, and when the cutting tool 4 comes into contact with the workpiece 1, the workpiece 1 4, the cutting process is started. Further, when the cutting tool 4 comes into contact with the workpiece 1, a closed loop 11 connecting the workpiece 1, the chuck 3, the mounting base 7, and the cutting tool 4 is formed.
detects the current, this is input to the control device 13, and the control device 13 detects the start of machining. In this manner, the closed loop 11 opens immediately after the workpiece 1 is machined by the movement of the cutting tool 4 and the cutting tool 4 is separated from the workpiece 1. Therefore, the energization sensor 12 detects the power outage and this is input to the control device 13, and the control device 13 controls the feeding device 8 to move the mounting base 7 backward in rapid traverse. The mounting base 7 is moved in parallel with the rotation axis 9 in rapid traverse control and returned to its original position. After this, the machined workpiece 1 is removed from the chuck 3, and a new workpiece 1 is attached to the chuck 3 and sequentially machined.

As described above, in the embodiment, the workpiece 1
When the cutting tool 4 comes into contact with the cutting tool 4, a closed loop 11 in which the DC power source 10 is connected in series is formed, and an energization sensor 12 is interposed in this closed loop 11, and this energization sensor 12 is connected to the control device 13. Non-cutting material 1
The end point of machining feed can be set immediately after leaving from. Therefore, the time required to return the cutting tool 4 to its original position after processing can be shortened, and the processing time can be shortened.

FIG. 2 shows a second embodiment of the present invention,
The same parts as in the first embodiment are given the same reference numerals, and detailed explanation thereof will be omitted. The second embodiment shows the case of a polishing apparatus, in which a grindstone 17 is provided facing a workpiece 1 attached to a chuck 3. This grindstone 17 is rotatable by a rotary drive device 18, and is provided with a feed device 8 so that it can move forward and backward in opposition to the workpiece 1. The grindstone 17 is made of a conductive member, and the contact between the grindstone 17 and the workpiece 1 forms a closed loop 11 in which the DC power source 10 is connected in series. Note that one end of the closed loop 11 is connected to the chuck 3, and the other end is connected to the feeding device 8. Further, on the mounting base 7 of the grinding wheel 15, a capacitance proximity switch 19, which is a non-contact detection part for detecting the workpiece 1, is slightly retracted from the tip of the grinding wheel 15 toward the non-cutting object 1. It is located in the same position.

Next, the operation of the above structure will be explained. After attaching the workpiece 1 to the chuck 3 in advance, the chuck 3 is rotated and the grindstone 17 is rotated by the rotation drive device 18.
Rotationally driven. Then, when the feeder 8 is activated,
The mounting base 7 to which the grindstone 17 is attached is rapidly moved toward the workpiece 1 side together with the capacitance proximity switch 19. When the capacitive proximity switch 19 approaches the workpiece 1, the controller 13 controls the feeder 8 to move the mounting base 7 at the machining speed, thereby moving the workpiece 1 toward the workpiece 1.
Cutting is started by the grindstone 17. Furthermore, whetstone 1
7 comes into contact with the workpiece 1, a closed loop 11 is formed, and as a result, current flows through the closed loop 11, the energization sensor 12 detects the current, which is input to the control device 13, and the control device 13 detects the start of machining. do. In this way, when the grindstone 17 moves a predetermined amount and the machining of the workpiece 1 is completed, the mount 7 is moved backward in rapid traverse, and then the controller 13 controls the feeder 8 to move the mount 7 back in rapid traverse. to return it to its original position. Workpiece 1 machined after this
is removed from the chuck 3, and a new workpiece 1 is attached to the chuck 3 and sequentially processed.

As described above, in the embodiment, the workpiece 1
A capacitive proximity switch 19 for detecting the grinding wheel 17 is integrally fixed to the mounting base 7, and the point when the capacitive proximity switch 19 approaches the non-cutting workpiece 1 is set as the starting point of machining feed. By doing so, the starting point can be set almost immediately in front of the workpiece 1. Therefore, the grinding wheel 1 is fast-forwarded.
It is possible to shorten the time until the start of processing according to 7. In addition, after the capacitance proximity switch 17 approaches and the grinding wheel 17 reaches the machining feed speed, the grinding wheel 17 can contact the workpiece 1 and start machining. There is no risk of colliding with object 1.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the machine tool may be a drill machine using a drill as a tool, and an optical sensor or the like may be provided as a detection part for the workpiece. Various modifications are possible.

[0014]

Effects of the Invention The present invention provides a machine tool in which a tool is rapidly fed by a feeding device to approach a workpiece, the tool moves at a machining feed rate and processes the workpiece, and then the tool retreats. wherein the tool is formed of a conductive member,
By forming a closed loop through contact between the tool and the workpiece, the end point of machining feed can be the point at which the tool leaves the workpiece after machining, reducing the time associated with feeding the tool during machining. Therefore, it is possible to provide a machine tool that can shorten machining time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the invention.

[Explanation of symbols]

1 Workpiece 4 Bit (tool) 8 Feeding device 11 Closed loop 13 Control device 17 Whetstone (tool)

Claims (1)

[Claims] 1. A machine tool in which a tool is rapidly traversed by a feeding device to approach a workpiece, the tool moves at a machining feed rate while machining the workpiece, and then the tool retreats. A machine tool characterized in that the tool is formed of a conductive member, and a closed loop is formed by contact between the tool and the workpiece, and a control device for the feeding device is connected to this closed loop.