Tube fixing structure and measuring head

Abstract

To provide a tube fixing structure that can miniaturize a connection part of a tube and facilitates insertion and removal of a tube, and to provide a measuring head.SOLUTION: A tube fixing structure (1, 1A) includes: a nipple (10, 110-1, 110-2, 112-1, 112-2, 210, 212) including an outer periphery that is provided with a protrusion; a tube (20, 120, 122, 220, 222) having flexibility and fitted to the nipple; and a spring (30, 30A) to be fitted to the tube that is fitted to the nipple and having an inner diameter that is smaller than an outer diameter of the tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tube fixing structure and a measurement head, and more particularly to a technique for fixing a tube used for supplying or discharging gas. [Background technology]

[0002] BACKGROUND ART Conventionally, tube joints and the like have been proposed for connecting and fixing a tube to a pipe to which the tube is to be connected.

[0003] Patent Document 1 discloses a resin tube joint for connecting resin tubes. The resin tube joint described in Patent Document 1 is designed so that, with a nut fitted onto the outer peripheral wall of the resin tube, the resin tube is pushed into a male thread formed on the joint body, and then the nut is screwed onto the male thread to clamp and secure the resin tube.

[0004] Patent Document 2 discloses a quick connector for connecting a resin tube to a mating pipe. The quick connector described in Patent Document 2 is configured to couple the quick connector and the resin tube by press-fitting a press-fit fixing portion into the interior of the resin tube. The press-fit fixing portion of the quick connector is provided with two annular biting portions with a sawtooth cross section and an annular pressure-welding portion formed between the two annular biting portions and having a smaller diameter than the annular biting portions. A step between the annular biting portions and the annular pressure-welding portion increases the depth of the annular biting portions' penetration into the inner surface of the resin tube.

[0005] Patent Document 3 discloses a sleeve for connecting a tube to a cylindrical body of a fitting. In the sleeve described in Patent Document 3, a first peripheral wall end faces the cylindrical body, and a second peripheral wall end is press-fitted into the open end of the tube. Then, a nut whose inner diameter narrows in three stages is screwed onto the cylindrical body, thereby sandwiching and fixing the tube between the nut and the sleeve.

[0006] Patent Document 4 discloses a tube coupling for connecting tubes. The tube coupling described in Patent Document 4 is equipped with a fitting having a double-cylinder structure formed from a single piece of springy sheet metal, and the outer cylindrical portion of the fitting is formed with a slot to allow for diameter reduction. Assembly is performed by inserting the end of the tube into the receiving portion of the fitting body of this tube coupling, and then pushing the fitting into the receiving portion. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-315982 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-085346 [Patent Document 3] Japanese Patent Publication No. 2020-085204 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-165377 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, measuring heads used to measure the shape or dimensions of workpieces may be provided with a gas pressure retraction function that uses gas pressure to move and retract the measurement part. In a gas pressure retraction function, gas is supplied and discharged through tubes fixed to the gas supply and discharge ports. Such gas supply and discharge ports are provided with nipples with barbs, and by fitting tubes into these nipples, the tubes can be connected to the gas supply and discharge ports. Simply fitting the tube into the nipple makes it difficult for the tube to come out due to the barb in the nipple, ensuring a certain level of pull-out strength.

[0009] However, the tube fitted to the nipple may swell due to the coolant and become more likely to come loose. Also, temperature changes at the tube connection point may cause the tube to become more likely to come loose.

[0010] Therefore, it is conceivable to provide a retainer that presses the tube against the connection point to ensure the tube's pull-out strength. However, providing a retainer poses the problem of increasing the size of the tube connection point. For example, in Patent Documents 1, 3, and 4, a receiving part such as a screw joint is required, which results in the connection point having a larger diameter than the diameter of the tube.

[0011] Since the measuring head is used inside processing equipment, etc., its components must be space-saving. Therefore, the diameter of the tube connection points, including the stoppers, must also be small.

[0012] Furthermore, when the press-fit fixing portion is press-fitted into the inside of the tube as in Patent Document 2, there is a problem that it becomes difficult to remove the tube.

[0013] The present invention has been made in consideration of these circumstances, and aims to provide a tube fixing structure and a measuring head that can reduce the size of the tube connection point and make it easy to insert and remove the tube. [Means for solving the problem]

[0014] The tube fixing structure according to the first aspect of the present invention comprises a nipple having a protrusion on its outer periphery, a flexible tube fitted into the nipple, and a spring fitted into the tube fitted into the nipple, the spring having an inner diameter smaller than the outer diameter of the tube.

[0015] A tube fixing structure according to a second aspect of the present invention is the first aspect, wherein the inner diameter of the tube is smaller than the maximum diameter of the convex portion.

[0016] A tube fixing structure according to a third aspect of the present invention is the tube fixing structure of the first or second aspect, wherein the spring is made of a spring material containing stainless steel.

[0017] A measuring head according to a fourth aspect of the present invention comprises a measuring section for measuring a workpiece, a nipple for supplying and discharging gas, and a tube for supplying and discharging gas via the nipple, and the tube is fixed to the nipple by a tube fixing structure according to any one of the first to third aspects.

[0018] The measuring head according to a fifth aspect of the present invention is the fourth aspect, and further comprises a retraction function that uses gas pressure to move and retract the measuring part. [Effects of the Invention]

[0019] According to the present invention, the tube is fixed to the nipple by pressing it with a spring, which makes it possible to reduce the size of the tube connection point.Furthermore, the tube can be easily inserted and removed while ensuring the pull-out strength of the tube. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a partial cross-sectional view showing a tube fixing structure according to an embodiment of the present invention. [Figure 2] 10A to 10C are perspective views showing the assembly procedure of the tube fixing structure. [Figure 3] 10A to 10C are partial cross-sectional views showing the assembly procedure of the tube fixing structure. [Figure 4] 10A and 10B are diagrams illustrating a tube fixing structure according to a modified example. [Figure 5] 10 is a diagram showing an example of a measuring head according to Application Example 1. FIG. [Figure 6] FIG. 10 is a diagram illustrating an example of a measuring head according to Application Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0022] [Tube fixing structure] FIG. 1 is a partial cross-sectional view showing a tube fixing structure according to one embodiment of the present invention.

[0023] As shown in FIG. 1, the tube fixing structure 1 according to this embodiment includes a nipple 10, a tube 20, and a spring 30.

[0024] The nipple 10 is formed roughly in the shape of a pipe (tube) and includes, in order from the insertion end that is inserted into the tube 20, protrusions (barbs) 12A and 12B, a flange 14, and a male thread portion 16. The nipple 10 is made of, for example, a metal (for example, stainless steel, specifically SUS303 (Japanese Industrial Standard JIS G 4303) or the like).

[0025] The barbs 12A and 12B are formed in a generally truncated cone shape that protrudes toward the outer periphery of the pipe-shaped nipple 10. As shown in Fig. 1, the cross section of each of the barbs 12A and 12B is generally a right-angled or obtuse-angled triangle. That is, in the cross section of the barbs 12A and 12B shown in Fig. 1, the slope on the insertion end side (left side in the figure) that is inserted into the tube 20 is gentler than the slope on the flange 14 side (right side in the figure). When the tube 20 is fitted into the nipple 10, the tube 20 is caught on the slope on the left side in the figure of the barbs 12A and 12B, preventing the tube 20 from coming out.

[0026] 1, the barbs 12A and 12B have the same shape and diameter, but they do not have to be the same. Furthermore, the cross-sectional shape of the barbs 12A and 12B is not limited to a right-angled or obtuse-angled triangle, and may be, for example, a wedge shape or a concave polygonal shape. Furthermore, the barbs 12A and 12B are provided at two locations along the longitudinal direction of the insertion end of the nipple 10, but they may be provided at three or more locations, or at just one location.

[0027] The flange 14 is formed in a substantially cylindrical shape that protrudes in the radial direction from the outer circumferential surface of the pipe-shaped nipple 10. In the example shown in FIG. 14The diameter R of the return 12A and 12B 12 (the diameter of the part that protrudes most outward; hereinafter also referred to as the maximum diameter), but is not limited to this.

[0028] 1, the barbs 12A, 12B and flange 14 are formed in an annular shape around the nipple 10, but this is not limiting. The barbs 12A, 12B and flange 14 may be protrusions formed at multiple locations around the nipple 10. However, from the perspective of ensuring airtightness between the nipple 10 and the tube 20, it is preferable that the barbs 12A and 12B be formed in an annular shape coaxial with the nipple 10.

[0029] The male thread portion 16 is formed on the end opposite the insertion end of the nipple 10 and is used to connect the nipple 10 to a pipe 50 .

[0030] The pipe 50 is connected to a flow path for supplying or discharging gas to a connected device (for example, a measurement head, etc.). An internal thread 56 is formed on the inner periphery of the end 52 of the pipe 50. On the other hand, an end 54 of the pipe 50 on the side of the device to which it is to be connected (for example, a measurement head) is connected to a gas flow path within the device. The male thread portion 16 of the nipple 10 is screwed into the female thread portion 56 of the pipe 50 and fixed, thereby connecting the nipple 10 to the gas flow path within the device.

[0031] In the example shown in FIG. 1, the pipe 50 is an L-shaped pipe with the end 52 and the end 54 at a substantially right angle, but the type of the pipe 50 to which the nipple 10 is connected is not limited to this.

[0032] The tube 20 is made of a flexible and airtight material (for example, a resin, specifically, polyurethane, etc.). 20 The diameter R of the return 12A and 12B 12 Therefore, when the tube 20 is fitted into the nipple 10, the tube 20 is expanded in diameter by taking advantage of its flexibility.

[0033] When the tube 20 is fitted into the nipple 10, a gas flow path C is formed that runs from the tube 20 through the nipple 10 and the pipe 50 to the device to which it is connected.

[0034] 1, the end 22 of the tube 20 is fitted until it abuts against the flange 14, but this is not limiting. For example, there may be a gap between the end 22 of the tube 20 and the flange 14, or the tube 20 may cover the flange 14. Furthermore, the flange 14 may be omitted, and the end 22 of the tube 20 may abut against the end 52 of the pipe 50.

[0035] 1, a tube 20 is fitted onto the insertion end side of the nipple 10. A spring 30 is fitted onto the portion of the tube 20 that extends from the insertion end of the nipple 10 to the flange.

[0036] The spring 30 is made of, for example, metal (for example, stainless steel, specifically SUS304-WPB (Japanese Industrial Standard JIS G 4314:2013) or the like). The spring 30 may be made of metal or spring steel such as stainless steel that has been subjected to a surface treatment such as plating, coating, or painting (including spring steel such as metal or stainless steel). Such surface treatment can improve the rust resistance and corrosion resistance of the spring 30.

[0037] The spring 30 has an inner diameter r in a normal state (before being expanded and fitted into the tube 20). 30 is the outer diameter R of tube 20 20 For example, the outer diameter R of the tube 20 is 20 If the inner diameter r is in the order of 1 mm, 30 R 20 A spring 30 that is smaller than the spring 30 by about 0.1 mm is used.

[0038] (Assembly Instructions) 2 and 3 are diagrams (a perspective view and a partial cross-sectional view, respectively) showing the assembly procedure of the fixing structure 1 for the tube 20.

[0039] First, the male thread portion 16 of the nipple 10 is screwed onto the end portion 52 (female thread portion 56) of the pipe 50 on the device side to connect the nipple 10 to the device side (Phase-1 in FIGS. 2 and 3).

[0040] Next, the tube 20 is fitted onto the nipple 10 (Phase 2), and the spring 30 is fitted onto the tube 20 (Phase 3).

[0041] In the sleeve of the existing product, the tube is held in place by a cylindrical retaining part that provides a tight fit to the barbed nipple. In contrast, in this embodiment, the tube is tightened by each spring 30, not by a surface like in the existing product. The spring 30 deforms to correspond to the shape of the barbs 12A and 12B of the nipple 10, so the tube 20 can be easily tightened by the barbs. 12A and 12B make it easier to bite in.

[0042] Furthermore, since the tube 20 is fastened by the tension of each turn of the spring 30, the overall fastening force is high but the fastening force of each turn is not very strong. Therefore, when removing the tube 20 from the nipple 10, it can be easily removed by stretching the spring 30 with a general tool such as pliers to reduce the tension.

[0043] The spring 30 according to this embodiment is made of metal (stainless steel), and therefore has the advantage of being resistant to deterioration caused by coolant. Furthermore, stainless steel is a common material and structure, and is therefore inexpensive.

[0044] Furthermore, compared to existing products that use a mechanism to tighten a tube with a nut to a nipple with a threaded joint (for example, Patent Document 1), there is no restriction on the nipple having to be thicker to thread it. Therefore, the nipple 10 can be made thinner, which has the advantage of increasing the degree of freedom in installation.

[0045] (Example) The results of measuring the pull-out strength of the fixing structure 1 for the tube 20 according to this embodiment (Example) and a threaded joint of an existing product (Comparative Example) are shown below. Here, in the Example, the maximum diameter (R 12 ) is φ3.0mm, material is SUS303, outer diameter of tube 20 (R 20 ) is φ4.1mm, inner diameter (r 20 ) is approximately 2.2 mm in diameter, made of polyurethane, and the inner diameter (r 30 ) had a diameter of 4.0 mm, a wire diameter of 0.8 mm, a length of approximately 6.4 mm, and was made of SUS304-WPB. In addition, as a comparative threaded joint, a nipple and tube with the same parameters and materials as those in this embodiment were used.

[0046] When the force (pull-out strength) required to pull the fixed tube from the nipple in the example and comparative example was measured using a force gauge, it was 71.8 N in the example and 46.6 N in the comparative example.

[0047] As described above, according to this embodiment, the pull-out strength when the tube 20 is fixed to the nipple 10 can be increased with a simple configuration.

[0048] [Variations] Fig. 4 is a diagram for explaining a tube fixing structure according to a modified example. For comparison, Fig. 4 illustrates the fixing structure 1 according to the above embodiment and a fixing structure 1A according to a comparative example side by side. Note that, to simplify the drawing, the tube 20 is omitted from the illustration.

[0049] The spring 30 in the fixing structure 1 according to the above embodiment is a tightly packed spring in which the windings are tightly packed with almost no gaps between them. Therefore, the pitch P of the spring 30 (the distance between the centers of the windings) is approximately equal to the wire diameter d of the spring 30 (P≈d).

[0050] In contrast, the spring 30A in the fixing structure 1A according to the modified example has a pitch P A is a compression spring whose wire diameter is larger than d. Here, the pitch P of the spring 30A is AFor example, A ≒2d.

[0051] In the case of the compression spring 30A, the inner diameter increases slightly when compressed, so by compressing the compression spring 30A when fitting and removing it, the force required for fitting and removing can be reduced.

[0052] [Application example 1] The fixing structures 1 and 1A according to the above-described embodiment and modified example are provided on a processing device such as a grinding machine. The present invention can be applied to the measuring head of a measuring device (gauge) for measuring a shape, a contour, a surface roughness, or the like.

[0053] Fig. 5 is a diagram showing an example of a measuring head according to Application Example 1. The measuring head 100 shown in Fig. 5 is a clamp-type measuring head that measures the outer diameter of a workpiece W. The measuring head 100 has a substantially line-symmetrical structure having a pair of measuring units (seesaw mechanisms) 101-1 and 101-2.

[0054] The measurement head 100 includes a measurement head housing 102, arms 104-1 and 104-2 rotatably attached to the measurement head housing 102 via fulcrum members 106-1 and 106-2, respectively, and contacts 108-1 and 108-2 fixed to the tips of the arms 104-1 and 104-2, respectively.

[0055] As shown in FIG. 5, when the measuring head 100 is set on the workpiece W, the contacts 108-1 and 108-2 are pressed against the surface of the workpiece W by biasing members (not shown), respectively, to sandwich the workpiece W. The contacts 108-1 and 108-2 then rotate and displace around the fulcrum members 106-1 and 106-2 in accordance with the dimensions of the workpiece W. The amount of displacement of the contacts 108-1 and 108-2 is detected by a detector (not shown, for example, a differential transformer (LVDT: Linear Variable Differential Transformer)) provided on the measuring head housing 102 side. The detection signal from the detector is output to the control device 150. The control device 150 calculates the dimensions of the workpiece W based on the detection signal input from the detector.

[0056] The measuring head 100 has a gas pressure type retraction function (for example, an air retraction function).

[0057] An opening for introducing air and an opening (pipe) for discharging air are provided in correspondence with each of the seesaw mechanisms 101-1 and 101-2 in the measuring head 100. The configuration of these pipes is the same as in the above embodiment.

[0058] Nipples 110-1 and 110-2 are attached to the air inlet openings of seesaw mechanisms 101-1 and 101-2, respectively. Tubes 120 are connected to nipples 110-1 and 110-2, and connected to a gas supply source via tubes 120. In Application Example 1, the gas supply source is an air supply unit (e.g., a pump) capable of supplying dry and clean air, or an air source such as an air supply unit provided in a facility where the measuring device is installed.

[0059] Meanwhile, nipples 112-1 and 112-2 are attached to the air discharge openings of seesaw mechanisms 101-1 and 101-2, respectively. Tubes 122 are connected to nipples 112-1 and 112-2, respectively. Tubes 122 are connected to a space to which air is discharged (for example, outside the measuring device or outside the facility where the measuring device is installed), and enable air to be discharged from the air retract mechanism.

[0060] When air is introduced into the air retract mechanism, the arms 104-1 and 104-2 each rotate, and the contactors 108-1 and 108-2 move from a retracted position where they do not come into contact with the workpiece W, etc., to a measurement position where the contactors 108-1 and 108-2 can come into contact with the workpiece W. On the other hand, when air is exhausted from the air retract mechanism, the arms 104-1 and 104-2 each rotate, and the contactors 108-1 and 108-2 move from the measurement position to the retracted position.

[0061] The connections between the nipples 110-1 and 110-2 and the tube 120, and between the nipples 112-1 and 112-2 and the tube 122 are made by using the tube fixing structure using the springs according to the above embodiment.

[0062] By applying the tube fixing structure according to the above embodiment, it is possible to reduce the size of the tube connection portion, and further to ensure the pull-out strength of the tube and to easily insert and remove the tube.

[0063] [Application example 2] 6 is a diagram (top view and side view) showing an example of a measuring head according to Application Example 2. The measuring head 200 shown in FIG. 6 is a measuring head for measuring the shape (for example, surface roughness or contour) of a workpiece W.

[0064] The measuring head 200 includes a measuring head housing 202, an arm 204 rotatably attached to the measuring head housing 202 via a fulcrum member 206, and a contactor 208 fixed to the tip of the arm 204. The arm 204 and contactor 208, which can rotate relative to the measuring head housing 202, are also referred to as a measuring unit (swinging unit) 201.

[0065] As shown in Fig. 6, when the measuring head 200 is set on the workpiece W, the contactor 208 is pressed against the surface of the workpiece W by a biasing member (not shown). The contactor 208 then rotates and displaces around the fulcrum member 206 in accordance with the dimensions of the workpiece W. The amount of displacement of the contactor 208 is detected by a detector (not shown) (for example, a differential transformer (LVDT: Linear Variable Differential Transformer)) provided on the measuring head housing 202 side. A detection signal from the detector is output to a control device (not shown), and the control device calculates the shape of the workpiece W based on the detection signal input from the detector.

[0066] The measuring head 200 has a gas pressure type retraction function (for example, an air retraction function).

[0067] An opening for introducing air and an opening (pipe) for discharging air are provided in the measurement head 200. The configuration of these pipes is the same as in the above embodiment.

[0068] A nipple 210 is attached to the air introduction opening. A tube 220 is connected to the nipple 210, and the tube 220 is connected to a gas supply source. In Application Example 2, the gas supply source is an air supply unit (e.g., a pump) capable of supplying dry and clean air, or an air source such as an air supply unit provided in a facility where the measuring device is installed.

[0069] Meanwhile, nipple 212 is attached to the air discharge opening. Tube 222 is connected to nipple 212. Tube 222 is connected to a space to which air is discharged (for example, outside the measuring device or outside the facility where the measuring device is installed), and allows air to be discharged from the air retract mechanism.

[0070] When air is introduced into the air retract mechanism, the arm 204 rotates, and the contactor 208 moves from a retracted position where it does not come into contact with the workpiece W, etc., to a measurement position where the contactor 208 can come into contact with the workpiece W. On the other hand, when air is exhausted from the air retract mechanism, the arm 204 rotates, and the contactor 208 moves from the measurement position to the retracted position.

[0071] The tube fixing structure using the spring according to the above embodiment is applied to the connection between the nipple 210 and the tube 220, and between the nipple 212 and the tube 222.

[0072] By applying the tube fixing structure according to the above embodiment, it is possible to reduce the size of the tube connection portion. Furthermore, it is possible to ensure the pull-out strength of the tube and This makes it possible to easily insert and remove the connector. [Explanation of symbols]

[0073] 1, 1A...fixing structure, 10...nipple, 12A, 12B...barb, 14...flange, 16...male thread portion, 20...tube, 22...end of tube 20, 30, 30A...spring, 50...pipe, 52, 54...end of pipe 50, 56...female thread portion, 100, 200...measuring head, 110-1, 110-2, 112-1, 112-2, 210, 212...nipple, 120, 122, 220, 222...tube

Claims

1. A nipple having a protrusion on its outer periphery; a flexible tube fitted onto the nipple; a spring fitted to the tube fitted to the nipple, the spring having an inner diameter smaller than an outer diameter of the tube; A tube fixing structure comprising:

2. The tube fixing structure according to claim 1 , wherein an inner diameter of the tube is smaller than a maximum diameter of the protrusion.

3. The tube fixing structure according to claim 1 , wherein the spring is made of a spring material including stainless steel.

4. a measurement unit that measures the workpiece; Nipples provided for supplying and discharging gas; a tube for supplying and discharging the gas via the nipple; A measuring head, wherein the tube is fixed to the nipple by a tube fixing structure according to any one of claims 1 to 3.

5. The measuring head according to claim 4 , further comprising a retraction function for moving and retracting the measuring unit by utilizing the gas pressure of the gas.

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