JP5698564B2 - Contact displacement measuring instrument - Google Patents

Description

  The present invention relates to a contact-type displacement measuring device, and more particularly to a contact-type displacement measuring device that detects a displacement amount when a contact is pressed against a measurement object via a differential transformer.

  Conventionally, for example, in various processing apparatuses, it is important to measure the shape of a workpiece with high accuracy in order to perform high-precision processing, and various displacement measuring instruments are used. The displacement measuring device includes, for example, a non-contact type displacement measuring device that optically measures the amount of displacement, and a contact type displacement measuring device that measures the amount of displacement by pressing a contact against an object to be measured.

  As a contact-type displacement measuring device, for example, a pencil-type contact-type displacement measuring device as described in Patent Document 1 is well known.

  FIG. 3 shows an example of a conventional contact displacement measuring instrument. FIG. 3 is a cross-sectional view of the contact-type displacement measuring head 100 which is a main part of the contact-type displacement measuring device. The contact-type displacement measuring head 100 has a contact 104 that can move up and down at the lower end of a cylindrical main body 102, and the contact 104 and the main body 102 are surrounded by a rubber bellows 106.

  A rod (probe member) 108 that is connected to the contact 104 and moves up and down together with the contact 104 is disposed inside the main body 102. The rod 108 is urged by a spring 110, and the contact 104 is urged downward (projecting direction) by urging the rod 108.

  A bearing (steel ball) 112 is disposed between the rod 108 and the main body 102 in order to make the movement of the rod 108 smooth. The bearing 112 is held by a retainer 114. Further, a lower end stopper 116 is provided inside the lower end of the main body 102 in order to restrict the downward movement of the linear ball bush constituted by the bearing 112 and the retainer 114.

JP 2005-201863 A

  However, when the conventional contact displacement measuring instrument as described above is installed in the vertical direction and continuously measured, the linear ball bushing falls downward due to the weight of the linear ball bushing itself and contacts the descending end stopper. If the contact does not fall down or there is interference with the linear ball bush at a position close to the measurement point, there is a problem that the measured value may vary due to the movement of the contact.

  On the other hand, as shown in FIG. 4, it is conceivable that the slide guide between the rod 108 and the main body 102 has a sliding bearing structure to stabilize the accuracy. Further, as shown in FIGS. 3 and 4, a bellows 106 is provided at the tip of a general pencil-type displacement measuring head to prevent foreign matter from entering the sliding portion of the contact 104, and the contact 104 sliding parts are protected.

  However, when the bellows 106 is provided in this way, for example, when the slide guide is a sliding bush type as shown in FIG. 4, the air in the bellows 106 when the contact 104 expands and contracts However, there is a problem that the movement of the contact 104 is affected and the measured value varies.

  At this time, as shown in FIG. 5 which shows a cross section perpendicular to the axial direction of the main body 102, an air escape portion 122 may be provided on the outer periphery of the rod 108 to reduce sliding resistance. By providing the air escape portion 122 in this way, the path when the air in the bellows 106 moves when the contact 104 expands and contracts becomes slightly larger and the sliding resistance can be reduced. There is a problem in that the measurement accuracy deteriorates due to backlash in the normal direction of the contact 104.

  Further, when the expansion and contraction speed of the contact 104 and the rod (probe member) 108 is high, the air escape from the sliding gap 120 does not catch up, and the air leaks from the gap of the dustproof bellows boot, thereby preventing the dust and waterproof. There is a problem that performance deteriorates.

  The present invention has been made in view of such problems, and in a contact displacement measuring instrument using a sliding bearing for the sliding portion of the probe member, the air movement in the bellows boot during the expansion and contraction of the probe member is smoothly performed. An object of the present invention is to provide a contact-type displacement measuring instrument that can prevent measurement value variation and perform high-precision measurement without damaging the dustproof and waterproof performance of the bellows boot even when the expansion speed of the probe member is high. And

  In order to achieve the above object, a contact displacement measuring instrument according to the present invention comprises a contactor that is displaceable by contact with an object to be measured, a probe member that is connected to the contactor and is displaced by a sliding bearing structure, and the contact A contact-type displacement measuring instrument comprising a bellows portion provided between a child and the probe member, and a contact-type displacement measuring head having a differential transformer that performs an output corresponding to the displacement of the probe member. The probe member is characterized in that a passage for escaping air in the bellows portion when the bellows portion expands and contracts with the displacement of the member is provided inside the probe member.

  As a result, in a contact-type displacement measuring instrument that uses a sliding bearing for the sliding part of the probe member, the movement of the air in the bellows boot during the expansion and contraction of the probe member is made smooth to prevent measurement value variation and the expansion and contraction speed of the probe member Even when the speed is high, high-precision measurement can be performed without impairing the dustproof and waterproof performance of the bellows boots.

  Moreover, as one embodiment, it is preferable that the passage communicates with the inside of the bellows part through a first opening provided in a side wall of the probe member lower part.

  Also, as one embodiment, the contact displacement measuring head is completely waterproof, and the contact displacement measuring head has an inside of the bellows portion when the bellows portion expands and contracts with the displacement of the probe member. It is preferable to provide an air reservoir formed in a variable volume in communication with the passage so as to store air.

  As a result, even when the contact-type displacement measuring instrument is completely waterproof, the probe member is absorbed by the air reservoir communicating with the passage formed inside the probe member when the probe member is displaced. It is possible to smoothly move the air in the bellows boot during expansion and contraction to prevent measurement value variation.

  Further, as one embodiment, in order to communicate the air reservoir and the passage, the passage is communicated with an upper gap in an outer cylinder forming a main body of the contact displacement measuring head and the passage. It is preferable that a second opening provided in the upper portion and a third opening communicating the upper gap in the outer cylinder and the air reservoir are provided.

  In one embodiment, the air reservoir is an air storage chamber in which at least a part of an outer wall provided at an upper part of an outer cylinder forming a main body of the contact displacement measuring head is formed of an elastic member. Is preferred.

  In one embodiment, the elastic member is preferably rubber.

  In this way, by forming an air reservoir in an air storage chamber in which a part of the outer wall is formed of an elastic member such as rubber, the probe member is displaced even when the contact displacement measuring instrument is completely waterproof. By absorbing the air in the bellows boot in the air storage chamber, it is possible to smoothly move the air in the bellows boot when the probe member expands and contracts, and to prevent variation in the measured value.

  As described above, according to the present invention, in the contact-type displacement measuring device using the sliding bearing for the sliding portion of the probe member, the air in the bellows portion when the bellows portion expands and contracts with the displacement of the probe member. By providing a passage for escaping inside the probe member and moving the air through the passage inside the probe member, the movement of the air in the bellows boot during the expansion and contraction of the probe member is smoothed, and measurement value variation is prevented and the probe member It is possible to perform highly accurate measurement without impairing the dustproof and waterproof performance of the bellows boots even when the expansion / contraction speed is high.

It is sectional drawing which shows the whole structure of the contact-type displacement measuring head of the contact-type displacement measuring device which concerns on one Embodiment of this invention. It is sectional drawing which shows the state which the probe member contracted in the contact-type displacement measuring head of FIG. It is sectional drawing which shows an example of the conventional contact-type displacement measuring device. It is sectional drawing which shows an example of the conventional contact-type displacement measuring device which made the sliding part the sliding bearing structure. It is sectional drawing perpendicular | vertical to the axial direction which shows an example of the conventional contact-type displacement measuring device which provided the escape path of the air in the sliding part.

  Hereinafter, a contact-type displacement measuring device according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing the overall configuration of a contact displacement measuring head of a contact displacement measuring instrument according to an embodiment of the present invention.

  As shown in FIG. 1, the contact displacement measuring head 1 of this embodiment includes a contact 4 that can move up and down at the lower end of an outer cylinder 2 that forms a cylindrical main body. Between them, a rubber bellows (bellows boots) 6 is provided.

  A probe member (rod) 8 that is connected to the contact 4 and moves up and down together with the contact 4 is disposed inside the outer cylinder 2. A core shaft 10 is attached to the top of the probe member 8, and the core shaft 10 is biased by a spring (compression spring) 11. Thereby, the probe member 8 is urged, and the contact 4 is further urged downward (in the protruding direction).

  The probe member 8 and the outer cylinder 2 are guided by a clearance 12 of several microns to constitute a sliding bearing.

  A core 14 constituting a differential transformer is attached to the other end of the core shaft 10 attached to the probe member 8, and the differential transformer is also constituted in the outer cylinder 2 ′ around the core 14 corresponding to the core 14. A coil unit 16 is incorporated.

  The bellows (bellows boots) 6 is dustproof, waterproof, and airtight in order to prevent foreign matters such as dust and water from entering the sliding bearing portion and protect the sliding portion of the probe member 8. . Further, the contact type displacement measuring head 1 of this embodiment is completely waterproof, and the upper part is also completely sealed.

  Therefore, when the contact 4 and the probe member 8 expand and contract, it is necessary to secure an air escape location so that the air in the bellows 6 can smoothly enter and exit from the bellows 6.

  Therefore, a passage 18 for allowing air to pass through the inside of the probe member 8 is formed, and an opening (first portion) for letting the air in the bellows 6 escape into the passage 18 when the probe member 8 expands and contracts. An opening) 20 is provided below the probe member 8.

  The air passage 18 provided in the probe member 8 is connected to an opening (second opening) 22 provided in the core shaft 10. The air that has passed through the passage 18 passes through the gap between the core shaft 10 and the outer cylinder 2 of the main body through the opening 22 provided in the core shaft 10 and further up through the gap between the upper core 14 and the coil unit 16. And flow.

  The detection signal of the differential transformer composed of the core 14 and the coil unit 16 is sent to an external controller (not shown) through a cable 26 disposed on the upper part of the coil unit 16.

  The cable connection portion 28 arranged on the upper portion of the differential transformer has a seal structure in the case of a completely waterproof specification like the contact displacement measuring instrument of the present embodiment, and the bellows 6 contracts and the bellows is contracted. When the air in 6 flows upward through the openings 20 and 22, there is no place to go.

  Therefore, in the present embodiment, an air storage chamber (air reservoir) 30 is provided as a buffer area for storing the air flowing into the cable connection portion 28 from the bellows 6.

  The air storage chamber 30 is provided in the outer cylinder 2 ′ that forms the main body of the contact displacement measurement head 1, and an opening (third opening) 34 is formed inside the cable connection portion 28, so that the cable 26 The air enters and exits the air storage chamber 30 through the opening 34.

  The outer wall of the air storage chamber 30 is a stretchable elastic wall 36 formed of an elastic member such as rubber. When air is stored in the air storage chamber 30, the elastic wall 36 is extended by the pressure of the air, and the volume of the air storage chamber 30 is increased, so that the air is absorbed into the air storage chamber 30. ing.

  A plurality (for example, two) of the air storage chambers 30 are formed around the cable connection portion 28, but the number of the air storage chambers 30 is not particularly limited, and may be formed as a continuous room over the entire circumference, for example. Further, the place where the air storage chamber 30 is installed is not particularly limited to the cable connection portion 28, and may be installed in another place.

  FIG. 1 shows a state in which the probe member 8 is extended. In this state, the bellows 6 is also extended, air is accumulated in the bellows 6, and the elastic wall 36 of the air storage chamber 30 is also shown. It is in a flat state.

  FIG. 2 shows a state where the probe member 8 is contracted.

  As shown in FIG. 2, when the contact 4 is pressed against an object to be measured (not shown), the contact 4 is pushed upward, the probe member 8 is also moved upward, and the bellows 6 is contracted. Thereby, the air in the bellows 6 flows upward through the opening 20 through the passage 18 formed in the probe member 8.

  The air that has flowed through the passage 18 in the probe member 8 flows into the outer cylinder 2 from the opening 22 provided in the upper portion thereof, and flows further upward through the gap between the core 14 and the coil unit 16 of the differential transformer. The air flows into the air storage chamber 30 from the portion 34.

  When air flows into the air storage chamber 30, the elastic wall 36 is pushed by the pressure and expands outward to expand, the volume of the air storage chamber 30 increases, and the air is absorbed.

  Thereby, the air that has flowed out due to the contraction of the bellows 6 moves through the passage 18 formed inside the probe member 8 and is stored in the air storage chamber 30. Therefore, the air flowing out from the bellows 6 can move smoothly, and the measurement accuracy is not deteriorated by affecting the movement of the sliding portion of the probe member 8.

  Displacement measuring instruments are often used mainly for dimensional inspection of parts during or after machining, and are required to measure with high accuracy and high speed. Here, since the non-contact displacement measuring instrument is sensitive to the work environment, the contact displacement measuring instrument is used in a relatively poor working environment. As described above, the contact displacement measuring instrument used in a poor measurement environment is required to be dustproof and waterproof.

  According to this embodiment, in such a completely waterproof contact displacement measuring instrument, by securing a place of air escape due to the contraction of the bellows, it is possible to support waterproofing with a sliding bearing (sliding bush) system, It becomes possible to perform highly accurate measurement.

  That is, since the air in the bellows boot when the probe member is expanded and contracted can pass through the passage formed in the probe member and the plurality of openings formed in the outer cylinder without resistance, the movement of the probe member As a result, the variation in measurement accuracy can be suppressed, and the dustproof and waterproof performance of the bellows boot can be prevented from being deteriorated.

  The example described so far is a contact type displacement measuring instrument with a completely waterproof specification. However, if the contact type displacement measuring head is not fully waterproof, the top of the contact type displacement measuring head is open. Without providing the storage chamber 30, the air flowing out from the bellows 6 flows upward through the opening 20, the passage 18 in the probe member 8, the opening 22, and the like, and is directly contacted from the upper opening. Just let it go outside.

  As described above, when the probe member is expanded and contracted, the air in the bellows is caused to flow through the opening to the air passage provided inside the probe member, and the air is allowed to escape to the outside through the opening at the upper part of the contact displacement measuring head. By doing so, even when it is not completely waterproof, the movement of the probe member sliding portion can be made smooth, and the deterioration of the measurement accuracy can be prevented.

  The contact displacement measuring instrument of the present invention has been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. Of course.

  DESCRIPTION OF SYMBOLS 1 ... Contact-type displacement measuring head 2, 2 '... Outer cylinder (main body), 4 ... Contact, 6 ... Bellows (bellows boot), 8 ... Probe member, 10 ... Core shaft, 11 ... Spring, 12 ... Clearance, DESCRIPTION OF SYMBOLS 14 ... Core, 16 ... Coil unit, 18 ... Passage (air formed in probe member), 20, 22 ... Opening part, 26 ... Cable, 28 ... Cable connection part, 30 ... Air storage chamber, 32 ... Gap , 34 ... opening, 36 ... elastic wall

Claims (6)

An outer cylinder forming a main body;
A contact that is provided at one end of the outer cylinder and is displaceable in contact with a measurement object;
A probe member disposed inside the outer cylinder, slidably supported by the outer cylinder by a sliding bearing structure, connected to the contact, and displaced together with the contact ;
A bellows part provided between the contact and the outer cylinder ;
A differential transformer that is disposed inside the outer cylinder and that performs output corresponding to the displacement of the probe member ;
A cable connecting portion provided at the other end of the outer cylinder and connected to a cable that outputs a detection signal of the differential transformer, the cable connecting portion having a seal structure
A contact-type displacement measuring device comprising a contact-type displacement measuring head having
A passage provided inside the probe member;
A first opening communicating the space formed inside the bellows portion and the passage;
A second opening communicating the space formed inside the outer cylinder and the passage;
An air storage chamber provided around the outer cylinder and having an outer wall formed of an elastic member;
A third opening communicating the air storage chamber and a space formed inside the outer cylinder;
Contact displacement meter, characterized in that it comprises a. The contact-type displacement measuring device according to claim 1, wherein the air storage chamber is formed around the cable connection portion. The contact-type displacement measuring device according to claim 2, wherein a plurality of the air storage chambers are formed around the cable connection portion. The contact-type displacement measuring device according to claim 2, wherein the air storage chamber is formed as a continuous chamber around the entire circumference of the cable connection portion. 5. The contact-type displacement measurement according to claim 2, wherein the third opening communicates a gap formed between an inner wall of the outer cylinder and the cable and the air storage chamber. vessel. Contact displacement measuring instrument according to claim 1, any one of 5, wherein the elastic member is a rubber.

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