Method of conclusion

Abstract

To provide a fastening method having improved position accuracy of a tool relative to a holder.SOLUTION: A fastening method fastens a cap that threadedly-engages with a holder holding a collet having a tool inserted therein, thus fastening the tool to the holder via the collet. The fastening method fastens the cap and then loosens it. Next, it fastens the cap again and then measures the position of the tool relative to the holder. Next, it loosens the cap, positions the tool relative to the holder based on a result of measurement of the position of the tool, and then fastens the cap.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fastening method.

Background Art

[0002] There is known a fastening method in which a cap screwed onto a holder holding a collet into which a tool is inserted is tightened to fasten the tool to the holder via the collet (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If there is a large variation in the position of the tool with respect to the holder, there is a risk of affecting the machining accuracy when such a tool is used for machining.

[0005] Therefore, an object of the present invention is to provide a fastening method with improved positional accuracy of the tool with respect to the holder.

Means for Solving the Problems

[0006] The above object can be achieved by a fastening method in which a cap screwed onto a holder holding a collet into which a tool is inserted is tightened to fasten the tool to the holder via the collet, the cap is tightened and then loosened, then the cap is tightened again and the position of the tool with respect to the holder is measured, then the cap is loosened and the tool is positioned with respect to the holder based on the measurement result of the position of the tool, and then the cap is tightened.

Effects of the Invention

[0007] According to the present invention, a fastening method with improved positional accuracy of a tool with respect to a holder can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0009] [Schematic Configuration of Tool Presetter 100] FIG. 1 is a schematic configuration diagram of a tool presetter 100. In addition, FIG. 1 shows an X-axis and a Y-axis that are orthogonal to each other. The X-axis is parallel to the horizontal direction, and the Y-axis is parallel to the vertical direction.

[0010] The tool presetter 100 includes a base 101, a photographing device 110, a tightening device 120, and a rotating device 130. On the side surface of the base 101, a rail 102 extending in the X-axis direction is formed. The photographing device 110 is engaged with the rail 102 so as to be movable in the X-axis direction, and is moved within a predetermined range in the X-axis direction by an actuator. The photographing device 110 is provided with a rail 112 extending in the Y-axis direction. The slider 114 is engaged with the rail 112 so as to be movable in the Y-axis direction, and is moved within a predetermined range in the Y-axis direction by an actuator. A camera 116 is attached to the tip of the slider 114. In this way, the camera 116 is supported so as to be movable within a predetermined range in the X-axis direction and the Y-axis direction.

[0011] The tightening device 120 is installed on the base 101 so as to face the photographing device 110. A rail 122 extending in the Y-axis direction is formed in the tightening device 120. The slider 126 is engaged with the rail 122 so as to be movable in the Y-axis direction, and is moved within a predetermined range in the Y-axis direction by an actuator. The slider 126 holds a movable member 124 extending in the X-axis direction so as to be movable in the X-axis direction. The movable member 124 is moved in the X-axis direction with respect to the slider 126 by an actuator. A tightening wrench 128 is fixed to the tip of the movable member 124. Thereby, the tightening wrench 128 is supported so as to be movable within a predetermined range in the X-axis direction and the Y-axis direction.

[0012] The rotating device 130 is provided inside the base 101 at a position between the photographing device 110 and the tightening device 120. The rotating device 130 is provided with a main shaft portion 132 and a wrench portion 134 that are rotatable in both directions around an axis C parallel to the Y-axis, which will be described in detail later. The main shaft portion 132 and the wrench portion 134 are independently rotatable by an actuator. Further, the wrench portion 134 passes through the main shaft portion 132 and is movable in the Y-axis direction within a predetermined range.

[0013] The controller 200 is a computer including volatile and non-volatile memories such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The controller 200 realizes various control processes related to the tool presetter 100 by executing a program installed in the memory on the CPU. Specifically, the controller 200 controls the above-described actuator and the camera 116 to fasten the holder 2 and the tool 10 described below.

[0014] [Schematic Configuration of Holder 2 and Tool 10] FIG. 2 is a schematic configuration diagram of the holder 2 and the tool 10. FIG. 2 shows the holder 2 and the tool 10 fastened to the holder 2. The holder 2 includes a main body portion 20, a collet 30, a cap 40, and a preset screw 50. The main body portion 20 has a substantially cylindrical shape and includes a body portion 21a, a flange portion 21b, a shank portion 21c, and a pull stud bolt 21d. The flange portion 21b is provided on the proximal end side of the body portion 21a and has an outer diameter larger than that of the body portion 21a. The shank portion 21c is provided on the proximal end side of the flange portion 21b, has an outer diameter smaller than that of the flange portion 21b, and is formed in a tapered shape in which the outer diameter gradually decreases toward the proximal end side. The pull stud bolt 21d is provided on the proximal end side of the shank portion 21c.

[0015] The collet 30 is substantially cylindrical and shorter in the axial direction than the main body 20, includes a through hole 31 and a tapered outer peripheral surface 32, and is attached to the tip side of the body portion 21a of the main body 20. The cap 40 is substantially bottomed cylindrical, includes a disc portion 41 and a cylindrical portion 42, and is attached to the tip side of the body portion 21a of the main body 20. The tool 10 is held in a shaft hole provided in the main body 20. Further, the tool 10 is held so as to penetrate the through hole 31. The tool 10 has a tip portion 11, a shoulder portion 12 protruding radially outward from the tip portion 11, and a base end portion 13. Note that the tool 10 is a drill, but it may be other tools such as a reamer. As shown in FIG. 2, the height from the lower end surface of the flange portion 21b to the tip portion 11 of the tool 10 is defined as the tip height L1, and the height from the lower end surface of the flange portion 21b to the shoulder portion 12 of the tool 10 is defined as the shoulder height L2.

[0016] On the tip side within the shaft hole of the body portion 21a, a tapered inner peripheral surface 23 is formed such that the inner diameter gradually decreases toward the base end side. The tapered outer peripheral surface 32 of the collet 30 has an outer diameter that gradually decreases toward the base end side and is in contact with the tapered inner peripheral surface 23. The disc portion 41 of the cap 40 is provided with a hole into which the collet 30 is fitted and engaged. A female screw portion 44 is formed on the inner peripheral surface of the cylindrical portion 42. A male screw portion 22 that screws into the female screw portion 44 is formed on the outer peripheral surface of the tip side of the body portion 21a. By rotating the cap 40 to adjust the screwing amount between the female screw portion 44 and the male screw portion 22, the collet 30 moves toward the base end side together with the cap 40. As a result, the tapered outer peripheral surface 32 moves toward the base end side with respect to the tapered inner peripheral surface 23, the collet 30 contracts in diameter, and the tool 10 passing through the through hole 31 of the collet 30 is fastened. In this way, by tightening the cap 40 that screws onto the main body 20, the tool 10 is fastened to the holder 2 via the collet 30. Although details will be described later, such fastening of the tool 10 to the holder 2 is performed by the tool presetter 100 described above.

[0017] The insertion hole 24 is continuous from the base end side with respect to the tapered inner peripheral surface 23, and is formed to be smaller than the inner diameter of the tapered inner peripheral surface 23 and larger than the outer diameter of the tool 10. A preset screw 50 that supports the base end portion 13 of the tool 10 is held in the insertion hole 24. A male screw portion 51 is formed on the outer peripheral surface of the preset screw 50. A female screw portion 25 is formed on the inner peripheral surface of the insertion hole 24. The male screw portion 51 and the female screw portion 25 are screwed together, and the preset screw 50 can be axially moved with respect to the main body portion 20 according to the amount of this screwing. An engaging portion 52 with which the tip of the above-described wrench portion 134 can engage is formed on the lower end surface of the preset screw 50. The relief hole 26 is continuous from the insertion hole 24 toward the base end side and is formed to be smaller than the inner diameter of the insertion hole 24, and penetrates to the base end of the pull stud bolt 21d.

[0018] [Fastening method] First, the fastening method in this embodiment will be described. FIG. 3 is a flowchart showing an example of the fastening method in this embodiment. First, the operator sets the holder 2 holding the tool 10 to the rotating device 130 of the above-described tool presetter 100 (step S1). Specifically, with the wrench portion 134 retracted in the downward direction of the Y axis, the operator holds the shank portion 21c of the holder 2 by the main shaft portion 132, and the tightening wrench 128 is gripped by the cap 40 by the controller 200. Note that in this state, the cap 40 is not tightened, and the tool 10 can be inserted into and removed from the holder 2, and the base end portion 13 of the tool 10 is supported by the preset screw 50.

[0019] Next, the controller 200 performs pre-tightening to pre-tighten the cap 40 with respect to the main body 20 (step S2). Specifically, the controller 200 rotates the main shaft portion 132 in one direction, and relatively rotates the main body 20 in one direction with respect to the cap 40 gripped by the tightening wrench 128. Next, the controller 200 loosens the cap 40 with respect to the main body 20 (step S3). Specifically, the controller 200 rotates the main shaft portion 132 in the direction opposite to the above-described direction, and relatively rotates the main body 20 in the opposite direction with respect to the cap 40. The significance of steps S2 and S3 will be described later.

[0020] Next, the controller 200 performs temporary tightening of the cap 40 with respect to the main body 20 in the same manner as in step S2 (step S4). Thereby, the tool 10 is temporarily fastened to the main body 20 of the holder 2 via the collet 30.

[0021] Next, the controller 200 measures the tip height L1 with the camera 116 (step S5), and then measures the shoulder height L2 (step S6). Next, the controller 200 calculates the difference component (L1 - L2) between the tip height L1 and the shoulder height L2 (step S7). Next, the controller 200 calculates the protrusion amount (step S8). The protrusion amount is a value obtained by subtracting the current tip height L1 from the target tip height TL1. The target tip height TL1 is calculated by adding the difference component (L1 - L2) to the target shoulder height TL2, and further adding the sinking amount assumed when the tool 10 is finally fastened to the holder 2.

[0022] Next, the controller 200 loosens the cap 40 with respect to the main body 20 to release the fastening of the tool 10 (step S9). Next, the controller 200 positions the tool 10 with respect to the main body 20 so as to have the above-described protruding amount (step S10). Specifically, with the spindle portion 132 stopped, the wrench portion 134 is inserted into the relief hole 26, the tip of the wrench portion 134 is engaged with the engaging portion 52 of the preset screw 50, and the wrench portion 134 is rotated in one direction. As a result, the screwing amount between the male screw portion 51 of the preset screw 50 and the female screw portion 25 of the insertion hole 24 is adjusted, and the preset screw 50 supports the base end portion 13 of the tool 10 to move the tool 10 axially with respect to the holder 2. In this way, the tool 10 is positioned with respect to the holder 1 based on the measurement results of steps S5 and S6. Note that the determination as to whether or not the protruding amount of the tool 10 has become the calculated protruding amount as described above is made based on the image of the camera 116.

[0023] Next, the controller 200 temporarily fastens the cap 40 by the method described above (step S11). Next, the controller 200 rotates the preset screw 50 so that the preset screw 50 is separated from the base end portion 13 of the tool 10 by the wrench portion 134 (step S12). Next, the controller 200 fully fastens the cap 40 by the method described above (step S13). As a result, the tool 10 is fastened by the cap 40 at the positioned position with respect to the main body 20. Next, the controller 200 brings the preset screw 50 into contact with the base end portion 13 of the tool 10 by the wrench portion 134 (step S14). In this way, the tool 10 is positioned and fastened with respect to the holder 2.

[0024] Next, the controller 200 performs a final measurement of the shoulder height L2 with the camera 116 (step S15). Next, the operator removes the holder 2 to which the tool 10 is fastened from the tool presetter 100 (step S16). Note that if the shoulder height L2 finally measured in step S15 is not within the desired range, the processes after step S4 may be performed again.

[0025] Next, the fastening method in the comparative example will be described. FIG. 4 is a flowchart showing the fastening method in the comparative example. The fastening method in the comparative example is different from the fastening method in the present embodiment, and steps S2 and S3 are not performed.

[0026] FIG. 5 is a graph showing the amount of sinking of the tool 10 into the holder 2 when the cap 40 is fully tightened after positioning the tool 10. The horizontal axis represents the number of fastening times [-], and the vertical axis represents the amount of sinking [mm]. FIG. 5 shows the measurement results of the amount of sinking when fastening from the first to the tenth time using the same type of tool 10 and holder 2 used in machining for both the present embodiment and the comparative example. As shown in FIG. 5, the variation in the amount of sinking is smaller in the present embodiment than in the comparative example. That is, FIG. 5 shows that the variation in the positional accuracy of the tool 10 with respect to the holder 2 is smaller in the present embodiment than in the comparative example. One of the reasons for this is considered to be the sludge adhering to the female screw portion 44, as will be described below.

[0027] FIG. 6A is a partially enlarged view of the female screw portion 44 of the cap 40 before the execution of steps S2 and S3 in the present embodiment. As shown in FIG. 6A, a plurality of sludges S are scattered in the female screw portion 44. The sludge S contains metal powder, lubricating oil, etc. The tool 10 is used while being mounted on the machining apparatus in a state of being fastened to the holder 2, but the sludge S penetrates inside from the gap between the cap 40 and the main body portion 20 during such machining and adheres to the female screw portion 44. FIG. 6B is a partially enlarged view of the female screw portion 44 of the cap 40 after the execution of steps S2 and S3 in the present embodiment. By performing steps S2 and S3, the sludge S scattered in the female screw portion 44 moves to the bottom of the valley portion of the female screw portion 44.

[0028] Figs. 7A and 7B are explanatory views of sludge S pushed into the bottom of the groove of the female screw portion 44. As shown in Fig. 7A, sludge S adheres to the female screw portion 44 before screwing. As shown in Fig. 7B, as the male screw portion 22 is screwed into the female screw portion 44 and the screwing amount increases, the crest of the male screw portion 22 is inserted into the bottom of the groove of the female screw portion 44. As a result, the sludge S adhering to the female screw portion 44 is pushed into the bottom of the groove of the female screw portion 44. In the comparative example, since steps S2 and S3 are not performed as described above, measurement, positioning, etc. are performed with the sludge S scattered in the female screw portion 44 and the cap 40 is finally tightened. On the contrary, in this embodiment, after steps S2 and S3 are executed and the sludge S is pushed into the bottom of the groove of the female screw portion 44, measurement, positioning, etc. are executed. As a result, in this embodiment, the variation in the amount of sinking of the tool 10 is suppressed more than in the comparative example. As a result, in this embodiment, the positional accuracy of the tool 10 with respect to the holder 2 is improved, and the accuracy of processing using such a tool 10 is also improved.

[0029] Therefore, the larger the tightening amount in the preliminary tightening of the cap 40 in step S2, the more the sludge S can be pushed into the bottom of the groove of the female screw portion 44. For this reason, the tightening amount in the preliminary tightening in step S2 is preferably at least larger than the tightening amounts in steps S4 and S11 and is equal to the tightening amount in the final tightening in step S13.

[0030] In the above embodiment, the tool 10 is positioned with respect to the holder 2 based on the measurement results of the tip height L1 and the shoulder height L2 (step S10), but the measurement method is not limited thereto. For example, only one of the tip height L1 and the shoulder height L2 may be measured to position the tool 10 with respect to the holder 2.

[0031] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of reference numerals

[0032] 2 Holder 10 Tool 20 Main body part 30 Collet 40 Cap 50 Preset screw

Claims

【Claim 1】 A fastening method for fastening a tool to a holder via a collet by tightening a cap that is screwed onto a holder holding the collet into which the tool is inserted, comprising: loosening the cap after tightening the cap; next, measuring the position of the tool relative to the holder after tightening the cap again; then, loosening the cap, positioning the tool relative to the holder based on the measurement result of the position of the tool, and then tightening the cap.

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