JP2000033535A - Blade tool breakage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blade tool breakage detection device capable of detecting the presence or absence of the breakage of a blade tool accurately without causing a failure. SOLUTION: This blade tool breakage detection device is provided with a sensing means 2 reacting to the change of pressure and a change means 5 producing a pressure different from a constant pressure in a flow passage in the flow passage whose pressure is held at the constant pressure. In this case, the change means 5 changes over to a condition in which a pressure is changed to a different pressure from a condition in which a pressure is held at a constant pressure mechanically by pushing an operation part 6 in by a blade tool 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool breakage detecting device used for confirming whether or not a tool used for drilling and tapping is broken.

[0002]

2. Description of the Related Art When drilling or tapping, if the tip of the cutting tool is broken, processing of the cutting tool will result in a defective product. Have been. Conventionally, as a tool breakage detecting device for the above-mentioned use, a method using a sensor such as a limit switch or a photoelectric sensor is generally known as a means for checking whether or not the tool has been broken. Both methods make use of the fact that the electrical signal obtained from the sensor differs between the case where a normal blade is used and the case where an abnormal blade is used (broken).

[0003] However, the limit switch has a drawback that it malfunctions due to the attachment of cutting fluid or chips during machining. In addition to the same disadvantages as the limit switch, the photoelectric sensor has a disadvantage that it malfunctions due to the refraction of light caused by the cutting fluid, and also has the disadvantage of being broken down by the cutting fluid.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to operate normally without failure and to accurately determine whether or not the cutting tool is broken. An object of the present invention is to provide a tool breakage detecting device capable of detecting the cutting tool breakage.

[0005]

According to a first aspect of the present invention, there is provided a tool breakage detecting device for detecting a breakage of a cutting tool in response to a change in pressure in a flow path maintained at a constant pressure. Changing means for changing the pressure from a state in which the pressure is changed to a state in which the pressure is changed from a state in which the operating part is maintained at a constant pressure to a state in which the pressure is changed to a different pressure by pressing the operating part with a blade tool. And

[0006] The cutting tool referred to herein means a cutting tool such as a drill, a tap, and a reamer. In addition, the method of pushing the operating unit of the changing means involves fixing the changing means at a fixed position and holding it in an immobile state, and moving the blade tool against the operating unit and pushing the operating unit, and conversely, moving the blade tool immovably. There is a method in which the operating unit is pressed against the cutting tool by holding the state and moving the changing unit with respect to the state. To switch to mechanical type
It means that the part is switched by direct movement,
It does not switch electrically. Note that oil and air are allowed to pass through the flow path.

[0007] A second aspect of the present invention is a cutting tool breakage detecting device, wherein a switching valve whose operating portion is biased by a spring is used as the changing means, and a pressure switch is used as the sensing means.

[0008] The switching valve used as the changing means is formed by pushing the operating portion with a cutting tool against the urging force of the spring.
The position is switched from the position for stopping the outflow of the fluid to the position for discharging the fluid to the outside. When the pushing is released, the position is switched to the original position by the restoring force of the spring, and the outflow of the fluid is stopped. Further, the pressure switch used as the sensing means switches when the pressure in the flow path decreases from a constant pressure,
When the pressure returns from the reduced state to the constant pressure, the switch is switched.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for detecting breakage of a cutting tool according to the present invention, as shown in FIG.
A pressure switch 2 serving as a sensing means, a first flow path 3 connecting the air pressure source 1 and the pressure switch 2, a second flow path 4 branched at an intermediate portion of the first flow path 3, and a second flow path. An air release valve 5 which is a change means connected to the front end of the flow path 4. When the operating portion 6 of the air release valve 5 is pushed in with the tip of the cutting tool 7, the air is released into the atmosphere. In this case, the pressure in the flow path is lowered from a constant pressure, and the pressure inside the flow path is maintained at a constant pressure when the flow path is not pushed.

The air release valve 5 is a mechanically operated switching valve. As shown in FIG. 2, a vent hole 9 serving as a flow path is provided in the center of a block-shaped main body 8 so as to penetrate vertically. A cylindrical sleeve 10 is screwed and fixed on the upper side, and a poppet 6 serving as an operation unit is provided so as to be vertically movable along the inside of the sleeve 10, and a direction in which the poppet 6 is projected above the main body 8 by a spring 11. Pressing on. An O-ring 12 is fitted on the outer periphery of the lower part of the sleeve 10 so as to be in close contact with the outer periphery of the sleeve 10 so that air does not leak from between the hole 9 and the sleeve 10. As shown in FIG. 2A, when the poppet 6 is not pushed in, the lower end surface of the sleeve 10 and the poppet 6 are in close contact with each other, so that air enters the main body 8 from below the hole 9. Is held in. As shown in FIG. 2B, when the poppet 6 is pushed in, the sleeve 1
Since a gap is formed between the lower end surface of the sleeve 0 and the poppet 6, air flows into the sleeve 10 from the gap and is released from the upper side of the sleeve 10 to the atmosphere. In addition, in the drawing, the air flow path is clarified with a space between the sleeve 10 and the poppet 6, but actually, the air flow path is close to each other.

The poppet 6 has a valve stem 13 that moves up and down along the inner surface of the sleeve 10 formed longer than the sleeve 10, and the lower end of the valve stem 13 is in contact with the lower end surface (valve seat) of the sleeve 10. The valve body 14 is provided, and a contact portion 15 is provided at the upper end of the valve rod 13 to contact the tip of the blade 7. The valve element 14 and the contact portion 15 are formed in a disk shape having a larger diameter than the valve rod 13. Since the air outlet formed in the gap between the upper end of the sleeve 10 and the valve rod 13 has a shape in which the upper portion is covered by the contact portion 15, cutting water and chips are less likely to adhere to the air outlet,
Even if it adheres, it is blown off by air when the poppet 6 is pushed in, so there is no risk of failure.

The spring 11 is housed in a contracted form in a cylindrical hollow portion 16 provided outside the height of the intermediate portion of the valve stem 13, the lower end of which is supported by the sleeve 10, and the upper end of which is the valve stem 13. Supported by. More specifically, the hollow portion 16 is formed so that the diameter of the lower portion from the middle portion of the valve stem 13 is slightly smaller than that of the upper portion, while the lower portion of the sleeve 10 corresponds to the lower portion of the valve stem 13. Is formed to have a smaller diameter than the upper portion, whereby a cylindrical hollow portion 16 is provided between the intermediate portion of the valve stem 13 and the inner surface of the sleeve 10.

The sleeve 10 has its upper end protruding in a flange shape as compared with a portion below it, and the depth of the sleeve 10 that fits in the main body 8 is determined. A female screw portion formed below the hole 9 of the main body 8 is for connecting to the second flow path 4.

The above-described blade tool breakage detecting device is used, for example, by setting as follows. The cutting tool breakage detecting device includes a cutting tool 7
An air release valve 5 is fixed to a part of a processing area of a cutting device (not shown) for driving the air conditioner, and an air pressure source 1 and a pressure switch 2 are respectively installed at a position different from the processing area. The cutting device performs two settings as an inspection method for a computer control unit (not shown) that drives the cutting tool 7. First, the cutter 7 is linearly reciprocated by a predetermined stroke amount with respect to the air release valve 5 fixed to the processing area, and when a normal cutter 7 is used, the tip of the cutter 7 is used. The poppet 6 of the air discharge valve 5 is pushed in by a predetermined depth, and when the broken blade 7 is used, the poppet 6 is set so as not to be pushed in. Second, when the signal from the pressure switch 2 is taken into the control unit and the pressure switch 2 is switched during one reciprocating movement of the blade 7, it is determined that the blade 7 is normal. If it is not switched, it is set so that the blade 7 is determined to be abnormal.

When the inspection is performed by the tool breakage detecting device set as described above, the result is as follows. First, when the reciprocating motion of the cutting tool 7 is started in a state where the flow path is maintained at a constant pressure by the air pressure source 1, when the cutting tool 7 is normal as shown in FIG. 6 is pushed in, the position of the air release valve 5 switches, and air is released into the atmosphere. Accordingly, the pressure in the flow path decreases from the constant pressure, so that the switch of the pressure switch 2 is switched, and the switching signal is transmitted to the control unit, and the control unit determines that the cutting tool 7 is in a normal state. In addition, when the blade 7 is broken as shown in FIG.
Return without reaching, so during one reciprocating movement,
Since the position of the air release valve 5 does not switch, the pressure in the flow path continues to be kept constant, and the control unit does not switch to obtain a signal, it is determined that the cutting tool 7 is broken.

[0016]

The first aspect of the present invention has the following effects. The switching method of the changing means for switching from a state in which the inside of the flow path is maintained at a constant pressure to a state in which the pressure is changed to a different pressure,
Since it is a mechanical type, not only does it not break down if cutting fluid or chips adhere to the operating part, it does not perform switching operation even if it adheres. Erroneous operation is eliminated. Also, since it has sensing means that responds to changes in pressure in the flow path,
By arranging this in a place where cutting fluid and chips do not adhere, failure or malfunction of the sensing means is eliminated. Since the malfunction of the changing means and the sensing means is eliminated in this way, by obtaining information from the sensing means, the pressure state in the flow path can be accurately known, and the normal condition of the cutting tool and the abnormal ( Since the information from the sensing means is different from when it breaks,
The presence or absence of breakage of the cutting tool can be accurately detected. Further, the present invention operates normally because the change means and the sensing means are not at risk of failure.

According to a second aspect of the present invention, the changing means includes:
Since the operation unit uses a switching valve biased by a spring, when the operation unit is released from being pushed, it returns to its original state naturally,
The pressure switch also switches when the pressure drops below a certain level, so when the operation unit is released, the operation returns to its original state naturally.As a result, the inspection is repeated many times. You can do it.

[Brief description of the drawings]

FIG. 1 is a pneumatic circuit diagram showing a tool breakage detection device of the present invention.

FIGS. 2A and 2B are diagrams showing a state immediately before the operating unit of the changing means is pushed with a normal cutting tool and a pushed state.

FIGS. 3A and 3B are diagrams showing a state in which the broken blade moves forward toward the operation unit and a state in which the operation unit cannot be pushed in. FIGS.

[Explanation of symbols]

 2 sensing means (pressure switch) 5 changing means (air release valve) 6 operating part 7 cutting tool 11 spring

Claims (2)

[Claims] 1. A flow path maintained at a constant pressure, comprising: sensing means (2) responsive to a change in pressure; and changing means (5) for changing the pressure in the flow path to a pressure different from the constant pressure. The changing means (5) is mechanically switched from a state in which the pressure is maintained at a constant pressure to a state in which the pressure is changed to a different pressure by pushing the operating portion (6) with the cutting tool (7). Detection device. 2. A sensing means (2), wherein a switching valve having an operating part (6) biased by a spring (11) is used as said changing means (5).
2. A pressure switch is used for the switch.
A tool breakage detection device as described in the above.