JPS6328742B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that when a tool such as a drill or tap senses contact with a workpiece and performs cutting by relative rotation between the tool and the workpiece, the cutting force is within a predetermined range. Furthermore, the present invention relates to a device for monitoring when a predetermined area is exceeded.

When a cutting edge of a tool is worn or damaged, the force applied to the tool due to cutting increases abnormally from the normal state, and this has conventionally been detected by measuring changes in the current of the main motor. With this tool, when the tool diameter was relatively large, the change in power (or current) was noticeable and could be easily measured, so there was no particular problem. However, when machining a small-diameter tool using a machine with a large main motor, it has the disadvantage that detection becomes impossible when the measured power (or current) is significantly smaller than the rated power (or current). In particular, small-diameter tools can be damaged even if a slightly excessive force is applied to them, so in order to ensure safe machining operations, a measure is desired to reliably detect the force applied to the tool. In order to reliably perform the specified machining, it is also essential to detect whether the tool length is shortened due to breakage, etc., and whether the required length is maintained. There is a strong need for this in work. For this reason, in order to detect the length of a tool attached to a spindle, methods have been proposed that use an auxiliary tool to know the position of the cutting edge and a limit switch, and detect the length of a light-receiving element by directing a beam of light to the object to be detected. There is. However, since these detection devices cannot perform detection during processing, there is the inconvenience of having to temporarily stop processing and perform detection, resulting in wasted time for detection. Utility Model No. 52-150087 is also known. Since this type does not detect thrust force but only detects torque, detection is unstable due to torque fluctuations due to changes in the processed material or the discharge of chips from the hole during drilling etc. .

The present invention has been made in view of the above, and provides an apparatus for monitoring the normal cutting sensing area and the abnormal cutting edge sensing area, including confirmation of a predetermined length of the tool, during machining operations. That is, the operation of a switching valve formed by a tool holder that has three pressure passages connected to a pressure source and a pressure switch and is fitted onto a rotating main shaft, and a valve body that is slidable in the axial direction within this holder. The valve body is configured to be displaced in the axial direction in response to the magnitude of the thrust force applied to the tool.

Next, embodiments of the present invention will be explained with reference to FIGS. 1 and 2.

In this embodiment, changes in the thrust force of the tool are detected by the displacement of the valve body. A tool holder 2 that is fitted into a tapered hole of a main spindle 1 of a machining center or the like by a tool changing mechanism or the like has a through hole with a step in the center. A tightening tool 3 and an adjuster 4 are screwed onto the tapered end of the tool holder 2 that fits into the main shaft tapered hole.
The other end of the tool holder 2 is slidable only in the axial direction by balls 5 inserted in guide grooves carved at equal intervals in the inner axial direction, and the outer end is equipped with a drill, tap, etc. A collet member 6 into which a tool is inserted is inserted. Therefore, the rotation of the main shaft 1 is transmitted from the tool holder 2 to the collet member 6 and the drill 7 without any problem. A valve body 8 is integrally formed at the inner end of the collector member 6. This valve body has two wide grooves 9 and 10 carved on its outer periphery, and is slidably fitted into the inner surface of the through hole of the tool holder 2 in an airtight manner. The holder 2 has grooves 9 and 10, respectively, when the valve body 8 moves.
Air passages 11, 12, and 13 communicating with the air passages 11, 12, and 13 are bored in the radial direction at axial positions. That is, by displacement of the valve body 8, the groove 9 is brought into communication with the passages 11 and 12, and the groove 10 is brought into communication with the passages 12 and 13. Valve body 8 is holder 2
A first spring 14 interposed between the collet member and the central step of the through hole is constantly biased to push the collet member outward and press it against the lid 15. This spring force corresponds to the axial force during normal cutting from contact with the drill, and the amount of compression of the spring determines the total stroke amount of the valve body 8. Further, a second spring 17 is inserted between the adjuster 4 and the stepped portion of the through hole via an intermediate stopper 16.
is interposed. The force of this spring has a spring constant stronger than that of the first spring 14, and when an abnormal force greater than that during normal cutting is applied to the valve body 8, the first spring 14 is compressed, and the spring 17 is compressed via the intermediate stopper 16. Compress. The force of the second spring 17 is adjusted by an adjuster 4 that matches the diameter of the drill or the like. An outer cylinder 18 is hermetically and rotatably fitted around the outer periphery of the tool holder 2 where the air passages 11, 12, and 13 are located, and is supported on the holder 2 by a bearing 19. and axially passage 1
Grooves 20 and 13 are arranged at intervals corresponding to 1, 12, and 13.
21 and 22 are carved on the inner peripheral surface. Outer cylinder 18
The protrusion 23 formed on the side of the
Through holes 24, 25, 26 are drilled in the groove 2.
0, 21, 22 and air passages 27, 28, respectively.
29. Through holes 24, 25,
Air passages 30, 31, and 26 are provided in the axial direction, respectively.
Connectors 33, 34, 35 having 32 are fitted in an airtight and slidable manner. The connector protrudes a certain amount toward the shank side of the tool holder 2, and its tip is hermetically connected to a connecting seat 36 provided on the quill of the main shaft 1. The drill side of the through holes 24, 25, and 26 is the lid 3.
7 is tightened and the connectors are in a state of being pushed out by the springs 38 interposed between the connectors and the connectors. The air passages 30, 31, and 32 of the connector are formed so as to be constantly connected to the passages 27, 28, and 29 of the outer cylinder 18, respectively. In particular, the central connector 34 is provided with a protrusion 39 that protrudes from the side surface of the outer cylinder 18, so that when the tool holder 2 is not inserted into the main shaft, the outer cylinder maintains a constant position relative to the drive keyway of the tool holder 2. It engages with the notch 40 of the tool exchange grip part of the tool holder 2. Also, the connector 34 can be engaged with the central notch 41 of the connecting seat 36 longer than the other two connectors 33 and 35, and when the tool holder 2 is inserted into the main shaft 1, the connector 34 is engaged with the notch 41. The outer cylinder 18 is positioned and pushed back by the connecting seat 36, and the protrusion 39 forms the notch 40.
The relationship between the two is resolved. Therefore, even though the outer cylinder 18 is positioned, the tool holder 2
Rotation is possible regardless of 8. At this time, the protrusion 39 engages with the notch 42 on the side surface of the outer cylinder to stabilize the outer cylinder. In this way, the three connectors are pressed into the holes of the connector seat by the force of the spring 38 and communicated with each other.
Of the three air passages, 31 is connected to a pressure air source via an electromagnetic switching valve, and air passages 30 and 32 are connected to a pressure switch, respectively. and air passage 30
The pressure switch that communicates with the workpiece senses when the drill touches the workpiece and moves a predetermined distance and operates within a predetermined range, indicating that the drill is of normal length and within the normal machining range. A pressure switch communicating with the passage 32 senses when a thrust force exceeding a predetermined value is applied to the drill and indicates an abnormal condition. When the tool holder 2 is stored in a magazine (not shown) and is not inserted into the main shaft, the outer cylinder 18 is engaged with the notch 40 of the magazine grip by the protrusion 39 of the connector 34, and is always connected to the drive keyway. maintains a certain relationship. When attached to the spindle by the tool changer, the keyway of the holder extends into the drive key (not shown) of the spindle. On the other hand, at this time, outer cylinder 1
The center connector 34 of 8 fits into the groove 41 of the connecting seat, and the protrusion 39 is separated from the notch 40 of the grip and engages with the notch 42 of the outer cylinder. Therefore, the outer cylinder 18
is released from the holder and fixed to the quill. When this installation is completed, the electromagnetic switching valve is actuated by a command, and pressurized air is sent to the connecting seat 36, the through hole 31 of the connector 34, and the air passages 28 and 12, and is ready. At this time, the valve body 8 is pushed toward the drill by the action of the first spring 14, and the air passage 12 is closed. Therefore, the pressure switches communicating with the air passages 11 and 13 are in a standby state. The spindle 1 moves forward according to the machining command, and the drill 7 comes into contact with the workpiece (a
position), and when the first spring 14 is compressed and retreated a predetermined distance, the groove 9 of the valve body 8 connects the air passages 12 and 11. In other words, the predetermined feed-out position of the spindle (b
position) is sensed by a pressure switch connected to the passage 11 to confirm that the drill is normal. If the above-mentioned sensing is not carried out within the specified range of the predetermined delivery amount, it is detected that the length does not have the required length due to wear and tear, etc., and is therefore unusable. The area up to the tool abnormality sensing position (position c) is the normal cutting position area. When the cutting edge of the drill wears out and the thrust force increases and exceeds the normal cutting area (position c), the air passage 12
and 11 are closed. Instead, the groove 10 is the passage 1
2 and 13, and a pressure switch connected to the air passage 13 detects an abnormality in the tool abnormality sensing area from this to the stroke range where the valve body 8 comes into contact with the stepped portion.

As explained above, pressurized air is supplied to one of the three air passages provided in the holder, and the valve body, which is moved in the axial direction by the thrust force applied to the tool, indicates that the pressure air passage has been switched. Because the switch is used for detection, it is possible to reliably detect unforeseen situations involving tools such as small-diameter drills and taps that are easily damaged, and to stably detect even when there are torque fluctuations. In addition, since it is possible to immediately take measures against the wear of the cutting edge of the tool, it is possible to prevent defects in the workpiece and damage to the machine. Therefore, it contributes to improving the reliability of unmanned operation of machining centers and the like. Furthermore, the contact position of the tool can be sensed, reducing idle cutting time.
It has a number of features that can improve cutting efficiency.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the embodiment, and FIG. 2 is a sectional view taken along line AA in FIG. 2...Tool holder, 6...Collection member, 8...
... Valve body, 14 ... First spring, 16 ... Intermediate stopper, 17 ... Second spring, 18 ... Outer cylinder, 11,1
2, 13, 27, 28, 29, 30, 31, 32
...Air passage, 33, 34, 35...Connector.

Claims (1)

[Claims] 1. A tool holder that has a plurality of radial air passages arranged in parallel in the axial direction and is attached to the main shaft, and a tool holder that is fitted so as to be displaced in the axial direction within the holder according to the magnitude of the thrust force applied to the tool. a valve body that slides in the holder in the axial direction in accordance with the axial displacement of the collet member; an outer cylinder having a passage fitted into the cylinder and communicating the air passage with a pressure side and a detection side, respectively;
It consists of a pressure source that supplies pressurized air to the pressure side and a detection means that senses pressure changes on the detection side, and a switching valve formed by a valve body and a holder is switched to the detection side according to the thrust force applied to the tool. An operating condition monitoring device for a drill-shaped tool, which is characterized by sensing pressure changes that occur.