JP2010089185A - Contact detector of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact detector of a machine tool which is miniaturized and capable of enhancing its reliability. <P>SOLUTION: By detaching at least any one of movable contacts 11, 12, 13 held by a movable contact holding unit 10 from pairs of steel balls 31 and 32, 33 and 34, 35 and 36 facing each other according to the contact of a stylus 2 with a workpiece, the predetermined electric potential is supplied to a base of a transistor 26 from a battery 6 via a resistance element 25, the transistor 26 is conducted thereby, a light emitting diode 8 is driven to emit the light, and the contact of the workpiece is detected thereby. Pattern electrodes 40-43 are formed on a substrate 30, the steel balls 31-36, the transistor 26 and the resistance element 25 are arranged on the substrate 30, and the wiring work is simplified thereby. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a contact detection device that detects contact with a workpiece to be measured, and more particularly to a contact detection device that is attached to a spindle of a machine tool.

  An example of a contact detection device that detects contact with a workpiece machined by a machine tool is described in Japanese Patent Application Laid-Open No. 8-108349 (Patent Document 1). This contact detection device performs centering and dimension measurement of a workpiece. A main body of a machine tool to which the contact detection device is attached is attached with a detection device main body, and a stylus is attached so as to protrude from the detection device main body. The tip contact at one end of the stylus contacts the workpiece.

  The other end of the stylus is provided with three support rods projecting radially outward. Each of the three support rods contacts between a pair of steel balls facing each other, and is supported by a spring. It is pressed in the axial direction. As a result, the stylus is swingably supported so as to swing in any direction against the urging force of the spring. A power source and a light emitter are connected between the detection device main body and the stylus, and when the tip contactor of the stylus comes into contact with the workpiece, the detection device main body is composed of a member including a steel ball and a support rod. The detection circuit is closed and the light emitter is turned on.

  The detection device body is filled with electrical insulating oil to prevent sparks and the like. For this reason, since electrical insulating oil adheres to the surface of the steel ball, the energization resistance between the support rod and the steel ball is large, the current flowing through the light emitter is small, and even if the light emitter is turned on, the amount of light is extremely high. There may be fewer or no lights at all.

  Therefore, in Patent Document 1, a current amplification circuit is connected in series to a light emitter, and the light emission body is turned on by flowing the amplified current by connecting the series circuit and the detection circuit in parallel to a power source. It is described.

  In Patent Document 1, the light emitter is turned on in response to the contact of the tip contactor of the stylus with the workpiece. As another example of the contact detection device, when the tip contactor of the stylus is not in contact with the workpiece. Japanese Patent Publication No. 58-17402 (Patent Document 2) discloses a measuring element that turns on the light emitter and turns off the light emitter when the stylus tip contactor contacts the workpiece. The measuring element described in Patent Document 2 is configured in the same manner as the contact detection device of Patent Document 1, but the above-mentioned two pairs of steel balls are electrically connected in series, and this series circuit, power source, and light emission are connected. Connected with the body.

When the tip contactor of the stylus is not in contact with the workpiece, the three support rods are in contact with the steel balls, so that a closed circuit is formed in which a current flows from the power source to the light emitter, and the light emitter is turned on. . When the tip contactor of the stylus comes into contact with the work, the stylus is displaced in the axial direction, so that one of the three support bars is separated from the steel balls facing each other, the electric circuit is cut off, and the light emitter is turned off.
JP-A-8-108349 Japanese Patent Publication No.58-17402

  Also in the measuring element described in Patent Document 2, since the electric insulating oil adheres to the surface of the steel ball, the current flowing through the light emitter is small when a workpiece is not detected, and the amount of light emitted from the light emitter is small. This causes a problem that it is difficult to distinguish between lighting and extinguishing. It is conceivable to provide the current amplifying circuit described in Patent Document 1 for such a measuring element. Although the current amplifier circuit includes a transistor and a resistance element, it is necessary to wire these elements in a narrow space. For this reason, there is a problem that labor for assembling work is required and the reliability of the wiring portion with the element is low.

  Therefore, the present invention is to provide a contact detection device for a machine tool that can be reduced in size and improved in reliability.

  The present invention relates to a contact detection device for a machine tool. The contact detection device includes a detection device main body attached to a spindle of a machine tool, a substrate fixed to the detection device main body, a tip contactor that is held so as to be able to contact with and separate from the substrate and contacts a workpiece that is a detection target. A stylus including a movable contact made of a conductive member facing the pair of fixed contacts so as to be able to come into contact with and separated from the pair, an electric circuit in which the pair of fixed contacts and the power supply unit are connected in the middle, and connected to the electric circuit A light emitting means that is mounted on the substrate, and a current amplifying means that amplifies the current flowing from the power supply unit to the electric circuit according to whether or not the movable contact contacts or separates from the pair of fixed contacts and causes the light emitting means to emit light. Is provided.

  By mounting a pair of fixed contacts and current amplifying means on the substrate, the apparatus can be miniaturized and not only wiring can be saved, but also costs can be reduced and reliability can be improved. .

  Preferably, a plurality of pairs of fixed contacts are provided on the substrate, and a plurality of movable contacts are provided around the other end of the stylus so as to face each pair of fixed contacts.

  When the stylus comes into contact with the workpiece, the movable contact is separated from one of the fixed contacts of each pair, so that the workpiece can be reliably detected.

  Preferably, the current amplifying means includes a transistor and a resistance element that causes a current to flow through the transistor in response to the movable contact being separated from the pair of fixed contacts.

  Since the current amplifying means can be configured by the transistor and the resistance element, the configuration can be simplified.

  Preferably, an opening for allowing the tip contactor of the stylus to pass through, a flexible diaphragm for closing the opening around the stylus, and a waterproof cover member for covering the diaphragm while allowing the tip contactor of the stylus to pass therethrough are included.

  The waterproof cover can prevent cutting water from entering the main body of the detection device.

  More preferably, the waterproof cover member includes an elastic member that surrounds the outer periphery of the stylus. The elastic member can prevent cutting water from entering between the stylus.

  According to the present invention, a pair of fixed contacts and current amplifying means are mounted on a substrate, and light is emitted by passing a current through the current amplifying means depending on whether or not the stylus tip contactor is in contact with the workpiece. Since the device emits light, not only can the apparatus be miniaturized, the labor of wiring can be saved, but also the cost can be reduced and the reliability can be improved.

  FIG. 1 is a side view showing a part of a machine tool contact detection device according to an embodiment of the present invention, and FIG. 2A is a sectional view taken along line IIA-IIA in FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A, and FIG. 3 is a perspective view showing an outline of the stylus, the movable contact, and the fixed contact. These are the electrical connection diagrams of the contact detection apparatus of a machine tool.

  1 to 3, a detection device main body 1 has a cylindrical shape and is attached to a main shaft of a machine tool (not shown), and a stylus 2 is attached so as to protrude from the detection device main body 1. The detection device main body 1 includes a base portion 3 and a head portion 4. A battery housing part 5 is formed in the base part 3, and a battery 6 is housed therein. The battery housing 5 is closed by a lid 7, and the battery 6 can be replaced by removing the lid 7. A light emitting diode 8 that operates as a light emitting means is accommodated on the stylus 2 side of the battery accommodating portion 5. The light emitting diode 8 emits light when the ball 21 which is the tip contactor of the stylus 2 contacts the workpiece. A window 9 is formed on the side wall of the base portion 3 so that the light emission of the light emitting diode 8 can be confirmed.

  The head portion 4 includes an opening having an opening on the stylus 2 side, and the stylus 2 is attached to the opening side so as to be displaceable in the axial direction. The stylus 2 has a ball 21 (tip contact) with which the workpiece contacts the tip. The other end of the stylus 2 is swingably supported by the detection device main body 1. That is, the movable contact holding part 10 is provided at the other end of the stylus 2. The movable contact holding part 10 is formed of an insulating member and is pressed in the axial direction of the stylus 2 by a spring 14. As shown in FIG. 3, the movable contact holder 10 is provided with three movable contacts 11, 12, and 13 that are spaced apart at an equal angle and project outward in the radial direction. The movable contacts 11, 12, 13 are formed of a conductive member. In the detection device main body 1, a substrate 30 is screwed to the tip holding portion 15 so as to surround the movable contact holding portion 10.

  The substrate 30 is formed in a ring shape as shown in FIGS. A pair of steel balls 31 and 32, 33 and 34, 35 and 36 made of a conductive member which operates as a pair of fixed contacts facing each of the three movable contacts 11, 12 and 13 are arranged on the substrate 30. Has been. The three movable contacts 11, 12, and 13 are provided so as to be able to contact and separate from each pair of steel balls 31 and 32, 33 and 34, 35 and 36, and the stylus 2 is not in contact with the workpiece. The three movable contacts 11, 12, and 13 come into contact with the respective pairs of steel balls 31 and 32, 33 and 34, 35 and 36, and when the stylus 2 comes into contact with the workpiece, any one of the movable contacts faces each other. Move away from the pair of steel balls.

  As shown in FIG. 2B, concave portions 37 and 38 are formed at positions where the steel balls 31 and 32 of the substrate 30 are arranged, and one end of the pattern electrode 40 is formed in the concave portion 38. . A groove 44 extending in the radial direction is formed between the steel balls 31 and 32 of the substrate 30 so that the movable contact 11 does not contact the substrate 30. The other end of the pattern electrode 40 extends to a recess (not shown) corresponding to the other steel ball 33 of the pair of adjacent steel balls 33 and 34. Therefore, the pattern electrode 40 electrically connects the steel balls 32 and 33. Similarly, the pattern electrode 41 electrically connects the steel balls 34 and 35. Note that grooves 45 and 46 are formed in the substrate 30 corresponding to the movable contacts 12 and 13 so that the movable contacts 12 and 13 do not contact the substrate 30.

  When the movable contact 11 is in contact with the steel balls 31, 32, the movable contact 12 is in contact with the steel balls 33, 34, and the movable contact 13 is in contact with the steel balls 35, 36, the pattern electrodes 40, 41, 42, 43 constitutes a part of an electric circuit. In the middle of the electric circuit, steel balls 31 to 36 and a battery 6 as a power source are connected in series as shown in FIG. One end of the pattern electrode 42 is connected to the steel ball 31, and one end of the resistance element 25 and the base of the NPN type transistor 26 are connected to the other end of the pattern electrode 42. Transistor 26 having a current amplification factor β of, for example, 100 or more is used, and amplifies the base current 100 times or more. The transistor 26 and the resistance element 25 constitute current amplification means.

  One end of a pattern electrode 43 is connected to the steel ball 36, and the emitter of the transistor 26 is connected to the other end of the pattern electrode 43. The other end of the pattern electrode 43 is grounded to the detection device main body 1. The collector of the transistor 26 is connected to the cathode of the light emitting diode 8, and the anode is connected to the other end of the resistance element 25 and the + electrode of the battery 6. The negative electrode of the battery 6 is grounded to the detection device main body 1.

  The opening portion of the head portion 4 is provided with a tip holding portion 15 having an opening, and the substrate 30 is screwed to the tip holding portion 15 as described above. The tip holding portion 15 is attached to a member 17, and the member 17 is attached to the base portion 3 via a member 18. The head portion 4 is provided with a diaphragm 16 formed from a flexible member such as rubber. The head portion 4 is filled with electrical insulating oil for preventing sparks and the like. The diaphragm 16 prevents the electrical insulating oil from leaking to the outside and prevents the cutting water when machining the workpiece from entering the head portion 4 from the outside. Since the diaphragm 16 is formed of a flexible member, the movement of the stylus 2 is not hindered.

  Next, the operation of the machine tool contact detection device according to the embodiment of the present invention will be described. In a state where the ball 21 of the stylus 2 is not in contact with the workpiece, the movable contacts 11, 12, and 13 are in electrical contact with the respective steel balls 31 and 32, 33 and 34, and 35 and 36 that face each other. . For this reason, the steel balls 31 to 36 are electrically connected, and the base of the transistor 26 is grounded. Since both the base potential and the emitter potential are the ground potential, there is no difference between the base potential and the emitter potential, so that the transistor 26 does not conduct. Although a current flows from the battery 6 to the ground side via the resistance element 25, the transistor 26 does not conduct, so the light emitting diode 8 does not emit light because no current flows.

  When the ball 21 of the stylus 2 comes into contact with the workpiece, the stylus 2 is displaced in the axial direction, and each pair of steel balls 31 facing at least one of the movable contacts 11, 12, 13 held by the movable contact holding unit 10. And 32, 33 and 34, and 35 and 36 are separated from contact. For example, when the movable contact 11 is separated from the steel balls 31 and 32 facing each other, the base potential of the transistor 26 is released from the ground potential, and the potential of the battery 6 is applied to the base of the transistor 26 via the resistance element 25. For this reason, the transistor 26 becomes conductive because a potential is generated between the base and the emitter. Since the transistor 26 has a high current amplification factor, even if the base current is small, a large current can flow through the collector. Therefore, a large current can flow through the light emitting diode 8 to emit light. The state where the light emitting diode 8 emits light can be confirmed through the window 9 formed in the base portion 3.

  As described above, the machine tool contact detection device according to the embodiment of the present invention is held by the movable contact holding unit 10 when the stylus 2 is displaced in the axial direction in response to the stylus 2 contacting the workpiece. The pair of steel balls 31 and 32, 33 and 34, 35 and 36 facing one of the movable contacts 11, 12, and 13 are separated from the battery 6 to the base of the transistor 26 via the resistance element 25. A potential can be supplied. Thereby, the transistor 26 becomes conductive, the light emitting diode 8 emits light, and the contact of the workpiece can be detected. Even if a film of electrical insulating oil is formed on the surfaces of the steel balls 31 to 36 and the energization resistance is large, at the time of workpiece detection, any one of the movable contacts 11, 12, 13 and the respective steel balls 31 and 32 facing each other, Since only the contact between 33 and 34, 35 and 36 is released, it is not affected by the conduction resistance.

  In one embodiment of the present invention, the pattern electrodes 40, 41, 42, 43 are formed on the substrate 30, and the resistance element 25 and the transistor 26 are directly connected to the pattern electrodes 42, 43. Can be formed on one substrate 30, so that the contact detection device can be miniaturized and the wiring labor can be saved, and the cost can be reduced and the reliability can be improved.

  In the above-described embodiment, the steel balls 31 and 32, 33 and 34, and 35 and 36 are provided to face the three movable contacts 11, 12, and 13, but at least one movable contact and If there is a pair of fixed contacts facing each other, the axial displacement of the stylus 2 can be detected.

  In the above-described embodiment, the light emitting diode 8 emits light when the stylus 2 comes into contact with the work. However, when the stylus 2 is not in contact with the work, the light emitting diode 8 emits light and comes into contact with the work. The circuit may be configured to be extinguished occasionally.

  Furthermore, although the NPN type transistor is used as the transistor 26 in the above-described embodiment, a PNP type transistor may be used. In addition, the transistor 26 and the resistance element 25 may be configured on an integrated circuit and disposed on the substrate 30.

  Furthermore, in the above-described embodiment, the steel balls 31 and 31, 33 and 34, 35 and 36 are used, but a needle roller may be used.

  Moreover, the above-mentioned embodiment arrange | positions the movable contacts 11, 12, and 13 so that it may protrude to radial direction outward with respect to the stylus 2, arrange | positions the steel balls 31-36 around the axis | shaft of the stylus 2, and a stylus. 2 is displaced in the axial direction, but the movable contacts 11, 12, 13 and the steel balls 31-36 are arranged in parallel to the stylus 2, and the movable contacts 11, 12, 13 are steel balls 31-36. The stylus 2 may be displaced in a direction orthogonal to the axial direction by pressing with a spring so as to be in contact with the stylus.

  FIG. 5 is a side view showing a part of a contact detection device for a machine tool according to another embodiment of the present invention.

  In this embodiment, the contact detection device for the machine tool shown in FIG. 1 is waterproofed. The contact detection device is used by being attached to the spindle of the machine tool, but when not in use, the contact detection device is attached to the tool magazine and enters a standby state. The tool magazine is often placed near the machine tool. When a workpiece is machined by attaching a tool to the spindle of a machine tool, cutting water is applied to the workpiece and the machining is performed. A large amount of this cutting water may be applied to the contact detection device mounted on the tool magazine. When this cutting water enters the detection device main body 1 of the contact detection device, moisture adheres to the substrate 30 and may cause a failure such as an insulation failure. A diaphragm 16 is attached to the contact detection device in order to prevent intrusion of cutting water. However, when a large amount of cutting water is applied, the diaphragm 16 alone is insufficient in waterproofing measures.

  Therefore, in the embodiment shown in FIG. 5, a waterproof cover 50 is provided as a waterproof cover member so as to cover the head portion 4 of the detection apparatus main body 1. The waterproof cover 50 is formed in a cylindrical shape having an inner diameter slightly larger than the outer diameter of the head portion 4 so as to be in close contact when the head portion 4 is covered and the cutting water does not enter.

  The waterproof cover 50 is formed of, for example, a metal material such as steel, but may be entirely formed of transparent acrylic so that the light emitting state of the light emitting diode 8 can be confirmed. Alternatively, the entire waterproof cover 50 may be formed of a metal material, and transparent acrylic may be fitted into a portion corresponding to the window 9 for confirming the light emission of the light emitting diode 8. The waterproof cover 50 is closed on the stylus 2 side, and a ring-shaped rubber 51 that is an elastic member is provided so as to surround the outer periphery of the stylus 2. More preferably, a waterproof ring is fitted between the waterproof cover 50 and the head portion 4.

  By providing the waterproof cover 50 in this way, it is possible to prevent the cutting water from entering the detection device main body 1 even if a large amount of cutting water is applied to the detection device main body 1. In particular, since the ring-shaped rubber 51 is fitted so as to surround the outer periphery of the stylus 2, the movement of the stylus 2 in the standby state can be reduced, and cutting water can enter from between the stylus 2 and the rubber 51. Less.

  For example, even if cutting water enters from between the stylus 2 and the rubber 51, the diaphragm 16 is attached to the detection device main body 1, so that a waterproof measure can be taken twice.

  The waterproof cover 50 may cover not only the head portion 4 but also the base portion 3.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a side view which fractures | ruptures and shows a part of contact detection apparatus of the machine tool in one Embodiment of this invention. FIG. 2A is a cross-sectional view taken along line IIA-IIA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. It is a perspective view which shows the outline | summary of a stylus, a movable contact, and a receiving part. It is an electric circuit diagram of the contact detection apparatus of the machine tool in one Embodiment of this invention. It is a side view which fractures | ruptures and shows a part of contact detection apparatus of the machine tool in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection apparatus main body, 2 stylus, 3 base part, 4 head part, 5 battery accommodating part, 6 battery, 7 lid, 8 light emitting diode, 9 window, 10 movable contact holding part, 11-13 movable contact, 14 spring, 15 Tip holding portion, 16 diaphragm, 17, 18 member, 21 ball, 25 resistance element, 26 transistor, 30 substrate, 31-36 steel ball, 37, 38 recess, 40-43 pattern electrode, 44-46 groove, 50 waterproof cover 51 rubber.

Claims (5)

A detection device body mounted on the spindle of the machine tool;
A substrate fixed to the detection device body;
A pair of fixed contacts made of conductive members disposed on and opposite to each other on the substrate;
A stylus including a tip contactor held in contact with and away from the substrate and in contact with a workpiece that is a detection target, and a movable contact made of a conductive member facing the pair of fixed contacts in contact with and away from the pair of fixed contacts. When,
An electric circuit in which the pair of fixed contacts and the power supply unit are connected in the middle;
Light emitting means connected to the electrical circuit;
A current amplifying unit mounted on the substrate and amplifying a current flowing from the power supply unit to the electric circuit according to whether or not the movable contact is in contact with or separated from the pair of fixed contacts; A machine tool contact detection device comprising: A plurality of pairs of the fixed contacts are provided on the substrate,
The contact detection device for a machine tool according to claim 1, wherein a plurality of the movable contacts are provided around the other end of the stylus so as to face each of the pair of fixed contacts. The current amplification means includes
A transistor,
The contact detection device for a machine tool according to claim 1, further comprising: a resistance element that causes a current to flow through the transistor in response to the movable contact being separated from the pair of fixed contacts. The detection device body includes:
An opening for passing the tip contact of the stylus;
A flexible diaphragm that closes the opening around the stylus;
The contact detection device for a machine tool according to any one of claims 1 to 3, further comprising a waterproof cover member that covers the diaphragm while passing the tip contact of the stylus.   The contact detection device for a machine tool according to claim 4, wherein the waterproof cover member includes an elastic member surrounding an outer peripheral portion of the stylus.

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