JP4349868B2 - Broach and broach device - Google Patents

Description

  The present invention relates to a broach and a broach device for cutting a hole in a workpiece.

  A broach used in a broaching device that cuts a hole in a workpiece is provided with a front gripping part for pulling the broach in the cutting direction, a cutting blade part, and a rear gripping part for pulling back the broach. Then, the workpiece is placed at a predetermined position on the table of the broaching device, the broach is lowered, the front gripping portion is entered into the hole of the workpiece, and the cutting blade is pulled out in the cutting direction along the processing center axis by the drawing device. The hole of the workpiece is cut by the part. In this cutting process, at the start of cutting, there is a clearance between the cutting blade part and the hole of the workpiece, and cutting is started with a misalignment within this clearance. During cutting, the flank of the cutting blade part The part with a clearance angle of 0 [deg.], That is, a straight land cuts the broach itself while correcting the misalignment with the workpiece.

  On the other hand, when a hardened quenching material of HRC50 to HRC65 is cut with a broach using an ultrafine particle cemented carbide for the cutting blade, the cutting is generally performed at a cutting speed of 35 m / min to 75 m / min. Therefore, machining accuracy can be ensured and machining can be performed efficiently. However, it is not realistic such as cutting burns or abnormal wear of the broach on the workpiece due to the rubbing pressure due to the 0 ° clearance angle. In addition, the misalignment between the workpiece and broach at the cutting start position causes a decrease in accuracy such as coaxiality and an uneven cutting amount, resulting in an excessive load on the cutting blade and a factor in reducing the tool life. At the same time, as the cutting temperature rises, the temperature of the cutting edge of the cutting blade rises, resulting in increased wear and reduced cutting efficiency.

  Therefore, various measures for suppressing the misalignment between the workpiece and the broach have been proposed. For example, as shown in FIG. 13, a cutting blade portion 102 for cutting holes Wa formed in the workpiece W is arranged on the outer periphery of the main body 101, and a shank 103 and a base portion of the shank 103 are disposed at the forward end of the main body 101. A broach 100 having a front guide 104, a polygonal cross-sectional shape of the front guide 104, an outer diameter substantially equal to the hole Wa, and an irregular surface in the axial direction. For example, see Patent Document 1).

  Further, as shown in FIG. 14, a guide portion 113 having a smaller diameter than the hole Wa is provided on the tip side of the cutting blade portion 112 of the broach 111 for cutting the hole Wa formed in the workpiece W, and the outer periphery of the guide portion 113 is further provided. A plurality of alignment members 114 having a tapered portion 114a that can be inserted and removed in the radial direction and have a tapered outer periphery are provided. Then, the work W is arranged on the support base 115 of the broach device so as to be horizontally movable, and the broach 111 is lowered. The axis of the workpiece W is slightly deviated from the axis of the descending broach 111, but when the guide 113 of the broach 111 enters the hole Wa of the workpiece W with the axis deviated, The aligning member 114 is not in contact with the inner diameter portion Wb, which is the inner peripheral surface of the hole Wa of the workpiece W. However, as the guide portion 113 advances, the aligning member 114 sequentially contacts the aligning member 114 from the position shifted to the axial center side. At the same time, the workpiece W moves horizontally so that the axis of the workpiece W coincides with the axis of the broach 111, and the cutting blade 112 is continuously inserted into the hole Wa of the workpiece W in a state where the axis is aligned. A broaching device that enters and cuts the hole Wa is known (for example, see Patent Document 2).

  Furthermore, the broach holder that holds the cutting edge of the broach is formed in a square bar shape having a polygonal cross section, and the guide hole of the work receiving jig that guides the broach holder is also made a polygonal cross section in accordance with the cross sectional shape of the broach holder. A guide device for a broach holder is known (see, for example, Patent Document 3).

JP-A-7-299648 JP-A-8-174332 JP-A-9-29536

  According to the broach 100 disclosed in Patent Document 1, the front guide has a polygonal cross-sectional shape at the base of the shank 103, the outer diameter is substantially equal to the hole Wa, and the surface of each ridge is formed as an uneven surface in the axial direction. By providing 104, the front guide 104 is concentrically held in the hole Wa of the workpiece W with high accuracy, so that machining accuracy is improved and biting of the front guide 104 into the hole Wa can be prevented.

  However, the centering by the front guide 104 and the hole Wa of the workpiece W is limited to the initial stage of the cutting process, and the concentricity is hindered by vibration and impact during the cutting process. As a result, abnormal wear such as chipping occurs in the cutting blade portion 102 of the broach 100, which causes a reduction in tool life and machining accuracy. Further, when cutting is performed at an economic processing speed, the front guide 104 may come into contact with the hole Wa of the workpiece W to cause damage or the like in the hole Wa of the workpiece W.

  According to the broach 111 disclosed in Patent Document 2, the guide portion 113 having a smaller diameter than the hole Wa is provided on the tip side of the cutting blade portion 112, and the tapered portion 114 a that is freely enterable / removed in the radial direction is provided on the outer periphery of the guide portion 113. By providing a plurality of alignment members 114 having a radial shape, the axes of the broach 111 and the hole Wa of the workpiece W can be aligned.

  However, the centering by the aligning member 114 and the hole Wa of the workpiece W is limited to the initial stage of the cutting process, and the concentricity is hindered by vibration and impact during the cutting process as in Patent Document 1, and the broach 111 There is a concern that abnormal wear such as chipping may occur in the cutting blade 112, and this causes a reduction in tool life and machining accuracy. Further, when cutting is performed at an economic processing speed, there is a risk that scratches or the like may occur in the hole Wa of the workpiece W by the aligning member 114 that comes into contact.

  According to the broach holder guide device disclosed in Patent Document 3, the broach holder that holds the cutting blade portion of the broach is formed into a square bar with a polygonal cross section, and the guide hole of the work receiving jig that guides the broach holder is also provided on the broach holder. By making the cross-sectional polygonal according to the cross-sectional shape, it is possible to prevent the broach holder from being displaced or fallen, and the processing accuracy is improved.

  However, since the cross-sectional shape of the broach holder is a polygonal cross-section, the shape of the broach is limited, the hole shape of the workpiece is limited, and when a hardened hardened material is cut at a high cutting speed, The broach holder formed in a polygonal shape may cause damage or the like in the hole Wa of the workpiece W.

  Accordingly, an object of the present invention made in view of such a point is to provide a broach and a broach device capable of cutting with high accuracy and efficiency.

  The invention of the broach according to claim 1, which achieves the above object, includes a columnar broach guide portion in which a plurality of cutting blade portions are arranged on the outer periphery continuously to a front grip portion provided at an end portion in a cutting direction. Formed in a centering jig in a broach that is provided and inserted into a hole drilled in the workpiece, pulled out in the cutting direction along the machining center axis, and cut into the hole in the workpiece by the cutting blade portion It is arranged on the same axis as the machining center axis, and can contact the jig side taper portion that expands in a conical shape as it moves in the cutting direction continuously to the broach insertion hole through which the broach guide portion can be inserted. A conical broach side taper portion is provided between the front grip portion and the broach guide portion so as to be concentrically provided with the broach guide portion and gradually reduce in diameter as it moves from the front grip portion side to the broach guide portion side. And wherein the Rukoto.

  According to the first aspect of the present invention, the cone gradually reduces in diameter as it moves from the front gripping portion side that can come into contact with the jig-side taper portion of the centering jig arranged coaxially with the machining center axis to the broach guide portion side. Since the broach side taper part is provided, the broach side taper part can be centered by contacting the broach side taper part with the jig side taper part, and the broach and workpiece are held coaxially with high accuracy. With the movement in the cutting direction, it can be avoided that the broach side taper part is separated from the jig side taper part and the work is damaged by the broach. Improvement and efficient cutting work become possible.

  According to a second aspect of the present invention, in the broach of the first aspect, the broach guide portion has a gap with an inner diameter portion of the broach insertion hole and can be inserted into the broach insertion hole in a non-contact manner. To do.

  According to the invention of claim 2, during the cutting process, the inner diameter part of the work and the broach guide part of the broach are maintained in a non-contact state, and the work is efficiently cut at an economical working speed without causing damage to the work by the broach. Cutting can be performed by the blade portion. In addition, when a broach shake or tilt due to vibration or impact occurs during cutting, the broach behaves due to contact between the inner diameter part of the broach insertion hole of the centering jig and the broach guide part. It is restrained and the processing accuracy by the broach can be secured.

  According to a third aspect of the present invention, the broach is inserted into a hole formed in the workpiece, and the broach is pulled out in the cutting direction along the machining center axis to cut the hole in the workpiece. In the broach device, a jig-side taper portion that is arranged coaxially with the machining center axis and expands in a conical shape as it moves in the cutting direction continuously to the broach insertion hole through which the broach guide portion of the broach can be inserted. A centering jig having a cylindrical broach guide portion having a plurality of cutting blades arranged on the outer periphery continuously to the front grip portion provided at the end in the cutting direction, and the front grip portion; Between the broach guide portion and the broach guide portion, a concentric shape that gradually decreases in diameter as it moves from the front gripping portion side to the broach guide portion side coaxially with the broach guide portion, and that can contact the jig side taper portion. A broach having a taper-side tapered portion, and a drawing device for clamping the front gripping portion of the broach and drawing the broach in the cutting direction along the machining center axis, and inserting the broach guide portion into the broach insertion hole Then, the broach side taper portion is brought into contact with the jig side taper portion, and the front grip portion is clamped by the pulling device and the broach is pulled out in the cutting direction along the processing center axis. Then, the hole of the workpiece is cut by the cutting blade portion.

  According to the invention of claim 3, the jig side taper portion, which is formed in the centering jig arranged coaxially with the machining center axis, is expanded in a conical shape, and the broach side taper portion of the broach is brought into contact. The broach is centered so that the broach and the workpiece are held on the same axis with high precision, and the broach side taper portion is separated from the jig side taper portion by pulling the broach in the cutting direction by a pulling device. It is possible to avoid causing damage to the workpiece by using the broach, and it is possible to perform cutting at an economical machining speed, thereby improving the machining accuracy of the workpiece and efficient cutting.

  According to a fourth aspect of the present invention, in the broaching device according to the third aspect, the broach guide portion has a gap with an inner diameter portion of the broach insertion hole and can be inserted in a non-contact manner.

  According to the invention of claim 4, during the cutting process, the inner diameter part of the work and the broach guide part of the broach are maintained in a non-contact state, and the work is efficiently cut at an economic working speed without causing damage to the work by the broach. Cutting can be performed by the blade portion. In addition, when a broach shake or tilt due to vibration or impact occurs during cutting, the broach behaves due to contact between the inner diameter part of the broach insertion hole of the centering jig and the broach guide part. It is suppressed and processing accuracy can be secured.

  According to a fifth aspect of the present invention, in the broaching device according to the third or fourth aspect, the centering jig has the jig-side taper portion formed on the inner periphery thereof, and enters the hole of the work and is on the jig side. A workpiece fitting portion is provided that expands the diameter by contact between the taper portion and the broach side taper portion, and the outer diameter portion contacts the inner diameter portion of the hole to center the workpiece.

  According to the invention of claim 5, the outer diameter portion of the workpiece fitting portion that expands the diameter by contact between the jig-side tapered portion and the broach-side tapered portion by entering the workpiece fitting portion of the centering jig into the hole of the workpiece. The centering of the workpiece can be reliably performed by bringing the hole into contact with the inner diameter portion of the hole.

  The invention according to claim 6 is the broaching device according to claim 5, further comprising a work presser for clamping the work centered by the centering jig.

  According to the invention of claim 6, by providing the work presser, the work can be held in the centered state, and the processing accuracy is improved.

  The invention according to claim 7 is the broaching device according to any one of claims 3 to 6, wherein the tool material of the cutting blade is an ultrafine particle cemented carbide and the cutting speed is 35 m / min to 75 m / min. It is characterized by that.

  According to the invention of claim 7, the tool material of the cutting blade is made of ultrafine particle cemented carbide, and the cutting speed is set at 35 m / min to 75 m / min, for example, a hardened quenching material of HRC50 to HRC65, etc. It is possible to ensure the machining accuracy and to process efficiently.

  According to the broach and broaching device according to the present invention, the conical shape formed on the centering jig is arranged between the front gripping part of the broach and the broach guide part, coaxially with the broach guide part and coaxial with the processing center axis. Since it has a conical broach side taper portion that gradually decreases in diameter as it moves from the front gripping portion side that can come into contact with the jig side taper portion that expands to the broach guide portion side, the broach side taper portion is placed on the jig side The broach can be centered by contacting the taper, the broach and workpiece are held coaxially with high accuracy, and the broach side taper of the broach is centered as the broach moves in the cutting direction. Since it is away from the taper on the centering side of the tool, it can be avoided that the work is damaged by broaching by centering, and cutting can be performed at an economic processing speed. It becomes possible to improve the machining accuracy of the workpiece and efficient cutting.

  Embodiments of the broach and broaching device of the present invention will be described below with reference to FIGS.

  FIG. 1 is a side view of the broach 1 in the present embodiment, and FIG. 2 is a cross-sectional view taken along the line II of FIG. The broach 1 includes a broach body 2 and a cutting blade portion 7, and a front grip portion 3 for pulling the broach 1 in the cutting direction F is provided at an end portion in the cutting direction of the broach body 2, and is continuous with the front grip portion 3. Then, a taper portion 4 which is a broach side taper portion and a columnar broach guide portion 5 are provided in order, and a rear grip portion 6 for pulling back the broach 1 is provided at the other end.

  The broach guide portion 5 is a columnar shape having an outer diameter that can be inserted into the broach insertion hole 37 in a non-contact state with a minute gap between the broach guide portion 5 and an inner diameter portion 38 of a centering jig 31 described later. The cutting blade portions 7 are radially arranged along the axial direction at equal intervals in the circumferential direction except for the rear portion range 5a of the portion 5. The tool material constituting the cutting blade portion 7 is, for example, an ultrafine particle type carbide capable of efficiently cutting a hardened material having a high hardness at a cutting speed of 35 m / min to 75 m / min, which is an economic processing speed. An alloy, at least the rake face and the cutting edge are coated with a hard coating.

  The tapered portion 4 has a conical shape having a large diameter on the front gripping portion 3 side and gradually decreasing in diameter as it moves to the broach guide portion 5 side, and is set coaxially with the broach guide portion 5 with high accuracy.

  FIG. 3 is a cross-sectional view of an essential part showing an outline of the broaching device 10. The broaching device 10 has an equipment table 11 having a through hole 11a. On the upper surface 11 b of the equipment table 11, a support base 12 that holds the workpiece W by opening a through hole 12 a is provided.

  On the upper surface 11b of the equipment table 11, a jig main body 14 having an upper plate 15 facing the upper surface 11b and having a through hole 15a opened is provided. Further, a plurality of plate guides 16 extending up and down are provided on the upper surface 11 b of the equipment table 11.

  A first plate 18 is supported on the plate guide 16 so as to be movable up and down so as to face the equipment table 11 and the upper plate 15 via a bush 17. The first plate 18 has a centering jig mounting hole 19 into which the centering jig 31 is fitted and a work holding through hole 20. The first plate 18 moves up and down while being guided by the plate guide 16 by the expansion and contraction operation of the first plate up-and-down operation cylinder 21 attached to the upper plate 15 of the jig body 14.

  Between the upper plate 15 and the first plate 18, there is provided a second plate 23 that moves up and down by an expansion and contraction operation of a second plate up and down operation cylinder 22 provided on the upper plate 15. A through hole 24 is opened in the second plate 23, and a base end of the work presser 25 whose front end 25 a protrudes below the first plate 18 through the work presser through hole 20 formed in the first plate 18. Is attached.

  Further, a lifter portion 26 that moves the broach 1 up and down by clamping the rear grip portion 6 of the broach 1 is disposed above the upper plate 15 of the jig body 14. On the other hand, a pulling device that enters the through hole 11a of the equipment table 11 at the raised position, clamps the front grip 3 of the broach 1 and pulls the broach 1 downward at an economic processing speed of, for example, 35 m / min to 75 m / min. 27 pull head portions 28 are provided.

  The through hole 11a of the equipment table 11, the through hole 15a of the upper plate 15, the centering jig mounting hole 19 of the first plate 18, the through hole 24 of the second plate 23, the lifter portion 26 and the pull head portion 28 are It is arrange | positioned coaxially with the process center axis line a extended in the direction.

  FIG. 4 is a plan view showing an outline of the workpiece W, and FIG. 1 shows a cross-sectional view taken along line II-II of FIG. The workpiece W has a substantially cylindrical shape, and a hole Wa extends in the axial direction. The groove extends in the axial direction from the inner diameter portion Wb serving as the inner peripheral surface of the workpiece W and is finish-cut by the cutting blade portion 7 of the broach 1. Wc is formed radially.

  The centering jig 31 is shown in a side view in FIG. 5, a sectional view in FIG. 5 in FIG. 6, and a sectional view in line III-III in FIG. 7 in FIG. 7. A base portion 32 into which the outer peripheral surface 33 is fitted into the tool mounting hole 19; a work fitting portion 35 having an outer diameter portion 36 which is continuous with the outer peripheral surface 33 via a stepped portion 33a and can enter the hole Wa of the workpiece W; Is continuous on the same axis and continuously along the axis from the upper end of the base portion 32 to the tip of the work fitting portion 35 so that the broach guide portion 5 of the broach 1 has a minute gap in a non-contact state. A substantially cylindrical shape through which a broach insertion hole 37 having an insertable inner diameter portion 38 passes, and a flange portion 34 is formed on the outer periphery of the upper end of the base portion 32 so as to come into contact with the upper surface of the first plate 18.

  Relief grooves 40 that extend in the axial direction and can move the cutting blade portion 7 of the broach 1 are radially formed in the inner diameter portion 38. The workpiece fitting portion 35 is equally divided radially by the relief groove 40, and the cutting blade portion 7 of the broach 1 passes through the divided portion (the relief groove 40 portion) of the workpiece fitting portion 35 during processing by inserting the broach 1. The groove Wc of the workpiece W can be finished and cut by the cutting blade portion 7 of the broach 1 on the outer periphery of the workpiece fitting portion 35. Further, along the inner periphery of the tip of the inner diameter portion 38, the diameter gradually increases in a conical shape as the workpiece fitting portion 35 moves toward the tip 35 a side, that is, in the cutting direction F, and can be brought into contact with the tapered portion 4 of the broach 1. A tapered portion 39 which is a tool side tapered portion is formed.

  The outer peripheral surface 33 of the base portion 32, the outer diameter portion 36, the inner diameter portion 38, and the taper portion 39 of the work fitting portion 35 are arranged coaxially, and the outer peripheral surface 33 is fitted into the centering jig mounting hole 19 of the first plate 18. By attaching the centering jig 31 to the first plate 18, the outer peripheral surface 33 of the base portion 32, the outer diameter portion 36, the inner diameter portion 38 and the taper portion 39 of the work fitting portion 35 are processed. Arranged on the central axis a.

  Next, cutting of the workpiece W by the broach 1 and the broaching machine 10 configured as described above will be described with reference to the flowchart of FIG.

  As shown in FIG. 3, the first plate up / down operation cylinder 21 and the second plate up / down operation cylinder 22 contract, the first plate 18 and the second plate 23 are in the raised position, and the rear grip 6 of the broach 1. Is clamped by the lifter 26 and the broach 1 is held in the raised position, and the tapered portion 4 and the front gripping portion 3 pass through the broach insertion hole 37 of the centering jig 31 and downward from the centering jig 31. It is held in a protruding state. The broach 1 is held so that the cutting blade portion 7 of the broach 1 is positioned corresponding to the position of the clearance groove 40 of the centering jig 31. In this state, the workpiece W is set on the support base 12 on the equipment table 11 so that the groove Wc of the workpiece W to be finished is positioned at the corresponding position of the cutting blade portion 7 of the broach 1 (step S1).

  Next, the lifter 26 is lowered as shown in FIG. As the lifter portion 26 is lowered, the broach 1 descends in the cutting direction F along the machining center axis a and enters the broach insertion hole 37 of the centering jig 31, and the front gripping portion 3 is a hole of the workpiece W. Clamping is performed on the pull head portion 28 of the drawing device 27 that passes through the through holes 12a of the support table 12 and enters the through holes 11a of the equipment table 11 (step S2).

  When the rear gripping portion 6 of the broach 1 is clamped to the lifter portion 26 and the front gripping portion 3 is clamped to the pull head portion 28, the tapered portion 4 of the broach 1 is positioned in the lower range within the hole Wa of the workpiece W. is doing.

  With the broach 1 held by the lifter part 26 and the pull head part 28, the first plate 18 is lowered by the extension of the first plate up / down cylinder 21. The tip 35a of the centering jig 31 held by the descending first plate 18 enters the hole Wa of the workpiece W, and the tapered portion 39 contacts the tapered portion 4 of the broach 1 (step S3).

  As shown in the enlarged view of part B of FIG. 8 in FIG. 9, this contact enters the hole Wa of the workpiece W and the tips 35a of the workpiece fitting portions 35 that are radially divided by the escape grooves 40 come into contact with each other. The outer diameter portion 36 comes into contact with the inner diameter portion Wb of the hole Wa of the workpiece W by being expanded following the taper portion 4 and the taper portion 39 of the centering jig 31, and the outer diameter portion 36 and the inner diameter portion Wb of the workpiece W are The gap between them disappears. The contact between the taper part 4 and the taper part 39 and the contact between the outer diameter part 36 and the inner diameter part Wb, that is, the clearance between the taper part 4 and the taper part 39 and between the outer diameter part 36 and the inner diameter part Wb of the workpiece W are zero. And mutual backlash disappears. Thereby, the hole Wa of the workpiece W, the broach insertion hole 37 of the centering jig 31 and the axis of the broach 1 are held with high accuracy on the machining center axis a, and the centering accuracy of the broach 1 and the workpiece W is ensured. The In this step S3, a gap is secured between the end face of the workpiece W and the stepped portion 33a of the centering jig 31, and no contact is made. Further, the broach 1 does not directly contact the work W, and the work W is not damaged by the broach 1.

  In a state where the workpiece W, the centering jig 31 and the broach 1 are centered, the second plate vertical movement cylinder 22 is extended to lower the second plate 23, and the workpiece pressing through hole 20 of the first plate 18. The workpiece W is pressed against the support base 12 by the workpiece presser 25 protruding downward from the workpiece W, and the workpiece W is clamped with the workpiece W centered by the support base 12 and the workpiece presser 25 (step S4).

  When the clamping of the workpiece W by the workpiece holder 25 is completed, the rear grip portion 6 of the broach 1 by the lifter portion 26 is unclamped.

  After the lifter portion 26 unclamps the rear knob 6 of the broach 1, the pull head portion 28 of the pulling device 27 moves down along the processing center axis a, and the front grip portion 3 is clamped to the pull head portion 28. 1 is drawn in the cutting direction F as shown in FIG. 10, and cutting of the groove Wc of the workpiece W by the cutting blade portions 7 of the broach 1 is started (step S5).

  Until the start of the lowering of the broach 1, the contact between the taper portion 4 of the broach 1 and the taper portion 39 of the centering jig 31 makes the hole Wa of the broach 1 and the workpiece W concentrically on the machining center axis a. Held in a state. As the broach 1 descends, the tapered portion 4 of the broach 1 moves away from the tapered portion 39 of the centering jig 31 and starts cutting the groove Wc of the workpiece W by the cutting blade portion 7. Further, during the cutting process in which the broach 1 is lowered at an economic machining speed of, for example, 35 m / min to 75 m / min, the inner diameter portion 38 of the centering jig 31 and the broach guide portion 5 of the broach 1 have a slight gap. In the contact state, the broach guide portion 5 does not cause scratches or the like on the inner diameter portion 38, and good cutting processing is performed while maintaining processing accuracy. Further, when the broach 1 is shaken or tilted due to vibration or impact during the cutting process, the broach guide portion 5 is not in contact with the inner diameter portion Wb of the workpiece W by the centering jig 31. The broach guide portion 5 of the broach 1 comes into contact with the inner diameter portion 38 of the centering jig 31 by a behavior such as runout and inclination within a range that does not substantially affect the cutting accuracy of the broach 1 while maintaining The behavior of 1 such as runout and tilt is suppressed, and machining accuracy is ensured.

  Further, the broach 1 is lowered, the cutting blade 7 is completely separated from the workpiece W, the cutting process is completed (step S6), and the broach 1 is completely removed from the hole Wa of the workpiece W as shown in the state after machining in FIG. Pull out. Even after this cutting blade portion 7 is separated from the workpiece W, the rear range 5a of the broach guide portion 5 is restrained from swinging the broach 1 by the inner diameter portion 38 of the centering jig 31, and the workpiece W by the broach 1 is reduced. The processing accuracy of the groove Wc can be ensured.

  After this cutting process, the second plate up-and-down operation cylinder 22 is contracted to raise the second plate 23, the work W is clamped by the work presser 25, that is, the work W is unclamped (step S7). The first plate up / down motion cylinder 21 is contracted to raise the first plate 18, and the work W on the support 12 is carried out (step S8).

  Thereafter, the pull head portion 28 is raised to raise the broach 1, the rear grip portion 6 of the broach 1 is clamped to the lifter portion 26, and then the front grip portion 3 of the broach 1 by the pull head portion 28 is released. Then, the lifter part 26 is raised to the position shown in FIG. 3 to raise the broach 1 and the pull head part 28 is lowered to complete the machining cycle (step S9).

  Therefore, according to the present embodiment, the contact between the tapered portion 4 of the broach 1 and the tapered portion 39 of the centering jig 31 and the contact between the outer diameter portion 36 and the inner diameter portion Wb of the workpiece W cause a hole in the broach 1 and the workpiece W. The workpiece W is clamped by the workpiece presser 25 and the support base 12 that can secure the centering of the workpiece W and is lowered while the Wa is held on the same axis with high accuracy, so that the workpiece W is cut by the cutting blade portion 7 of the broach 1. Until the start of the cutting process for cutting the groove Wc, the contact between the tapered part 4 of the broach 1 and the tapered part 39 of the centering jig 31 holds the hole Wa of the broach 1 and the workpiece W coaxially with high accuracy. As the broach 1 is lowered, the taper portion 4 of the broach 1 is separated from the taper portion 39 of the centering jig 31 and the cutting edge 7 can cut the groove Wc of the workpiece W.

  Further, during the cutting process, the inner diameter portion Wb of the workpiece W and the broach guide portion 5 of the broach 1 are maintained in a non-contact state with a slight gap, and the broach 1 is economical without causing damage to the workpiece W. The groove Wc can be efficiently cut by the cutting blade portion 7 at the processing speed. Further, when a behavior such as runout or tilt of the broach 1 due to vibration or impact occurs during cutting, the broach is brought into contact with the inner diameter portion 38 of the centering jig 31 and the broach guide portion 5 of the broach 1. 1 is suppressed, and the broach guide portion 5 has a rear range 5a that is not swung by the inner diameter portion 38 of the centering jig 31 even after the end of cutting when the cutting blade portion 7 is completely separated from the workpiece W. The processing accuracy of the groove Wc of the workpiece W by the broach 1 can be secured.

  Therefore, the coaxial state of the workpiece W and the broach 1 is maintained with high accuracy over the entire range of normal cutting, and the workpiece W and the broach 1 except for the cutting blade portion 7 are held in a non-contact state. Cutting at an economic processing speed can be performed with high accuracy, and the inner diameter portion of the centering jig 31 can be used when the broach 1 is shaken or tilted due to vibration or impact during the cutting. 38 and the broach guide part 5 of the broach 1 are restrained, the behavior of the broach 1 is suppressed, and a processed product with excellent machining accuracy can be secured, and the misalignment of the cutting amount is suppressed by suppressing the misalignment of the workpiece W and the broach 1. Abnormal wear such as chipping can be avoided in the cutting blade portion 7 of the broach 1 and the tool life is improved.

(Example)
The inner diameter portion Wb made of a hardened HRC50 to HRC65 is finished by a conventional processing method that does not use the centering jig 31 and a processing method that uses the centering jig 31 and the broach 1. The position W of the cutting blade 7 with respect to the broach guide portion 5 is 4 μm, the gap between the broach guide portion 5 and the inner diameter portion Wb is 7 μm to 30 μm, and the cutting speed is 35 m. Cutting was performed at / min to 75 m / min.

  As a result, when the deviation of the center of the inscribed circle in which the reference pin is brought into contact with the groove Wc is measured with reference to the inner diameter portion Wb of the cut workpiece W, the centering jig 31 is used as shown in FIG. In the conventional cutting that is not performed, the machining accuracy is 6 μm to 18 μm, whereas the centering jig 31 of the present embodiment and the broach 1 having the tapered part 4 that contacts the tapered part 39 of the centering jig 31 are provided. According to the cutting processing used, the processing accuracy was 2 μm to 4 μm, and a significant improvement in processing accuracy could be confirmed.

It is a side view of the broach in the embodiment of the present invention. Similarly, it is the II sectional view taken on the line of FIG. Similarly, it is principal part sectional drawing which shows the outline | summary of a broaching apparatus. Similarly, it is a top view which shows the outline | summary of a workpiece | work. Similarly, it is a side view of a centering jig. Similarly, it is the II-II sectional view taken on the line of FIG. Similarly, it is the III-III sectional view taken on the line of FIG. Similarly, it is principal part sectional drawing of the broaching device which shows the outline in the middle of a process. Similarly, it is the B section enlarged view of FIG. Similarly, it is principal part sectional drawing of the broaching device which shows the outline | summary after a process. Similarly, it is a flowchart which shows a processing process. It is explanatory drawing which shows this invention and the conventional processing precision. It is explanatory drawing which shows the outline | summary of the cutting by the conventional broach. Similarly, it is explanatory drawing which shows the outline | summary of the cutting process by the conventional broach.

Explanation of symbols

1 Brooch 2 Brooch body 3 Front grip 4 Tapered part (Broach side taper part)
DESCRIPTION OF SYMBOLS 5 Broach guide part 7 Cutting blade part 10 Broaching device 12 Support stand 25 Work holding | maintenance 26 Lifter part 27 Pulling-out apparatus 28 Pull head part 31 Centering jig | tool 32 Base part 33 Outer peripheral surface 35 Work fitting part 36 Outer diameter part 37 Broach insertion hole 38 Inner diameter part 39 Taper part (Jig side taper part)
40 Escape Groove a Machining Center Axis W Work Wa Hole Wb Inner Diameter Wc Groove F Cutting Direction

Claims (7)

A cylindrical broach guide part with a plurality of cutting blades arranged on the outer periphery is provided in succession to the front grip part provided at the end in the cutting direction, and is inserted into the hole drilled in the workpiece. In a broach that pulls out in the cutting direction along the axis and cuts the hole of the workpiece by the cutting blade part,
A jig-side taper that is arranged coaxially with the machining center axis formed in the centering jig and expands in a conical shape as it moves in the cutting direction continuously to the broach insertion hole through which the broach guide portion can be inserted. A conical broach that is provided between the front gripping part and the broach guide part and is coaxial with the broach guide part and gradually reduces in diameter as it moves from the front gripping part side to the broach guide part side. A broach having a side taper portion.   2. The broach according to claim 1, wherein the broach guide portion has a gap with an inner diameter portion of the broach insertion hole and can be inserted into the broach insertion hole in a non-contact manner. In a broach device that inserts a broach into a hole drilled in a workpiece, and pulls out the broach in the cutting direction along the machining center axis to cut the hole in the workpiece.
A centering jig having a jig-side taper portion which is arranged coaxially with the machining center axis and expands in a conical shape as it moves in the cutting direction continuously to a broach insertion hole through which the broach guide portion of the broach can be inserted. Ingredients,
A cylindrical broach guide portion having a plurality of cutting blades arranged on the outer periphery is provided continuously to the front grip portion provided at the end in the cutting direction, and between the front grip portion and the broach guide portion. A broach having a conical shape whose diameter gradually decreases as it moves from the front gripping part side to the broaching guide part side on the same axis as the broaching guide part and having a broaching side taper part that can contact the jig side taper part,
A drawing device for clamping the front grip portion of the broach and drawing the broach in the cutting direction along the machining center axis;
The broach guide part is inserted into the broach insertion hole, the broach side taper part is brought into contact with the jig side taper part, and the front grip part is clamped by the pulling device along the center axis of machining. The broaching apparatus is characterized in that the broach is pulled out in the cutting direction and the hole of the workpiece is cut by the cutting blade portion.   The broaching device according to claim 3, wherein the broach guide part has a gap with an inner diameter part of the broach insertion hole and can be inserted in a non-contact manner.   The centering jig is formed with the jig-side taper portion on the inner periphery, enters the hole of the workpiece, and expands the diameter by contact between the jig-side taper portion and the broach-side taper portion. 5. The broaching device according to claim 3, further comprising a workpiece fitting portion that contacts the inner diameter portion of the hole to center the workpiece.   The broaching device according to claim 5, further comprising a work presser for clamping the work centered by the centering jig.   The broaching device according to any one of claims 3 to 6, wherein the tool material of the cutting blade portion is an ultrafine particle cemented carbide and the cutting speed is 35 m / min to 75 m / min.

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