JP2011189446A - Tap holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tap holder, minutely expandable in the axial direction, without looseness in the axial direction and the rotational direction, by adjusting an expansion quantity with a simple structure. <P>SOLUTION: The tap holder includes a shank having a cylindrical part for arranging a plurality of through-holes in the circumferential direction, a holder body slidably fitted to the outside of the cylindrical part and forming a locking hole in a position corresponding to the through-holes, a bolt stored in the cylindrical part, having a head part and a shaft part and forming a tapered part on the lower side of the head part, a washer out-fitted to the shaft part of the bolt and forming a tapered part toward the head part of the bolt, a nut threaded into a screw distal end part of the bolt, a spiral spring out-fitted to the shaft part of the bolt, having one end allowed to abut on the washer and having the other end allowed to abut on the nut, and a steel ball stored in the through-holes, having one side supported by a circumferential part of the locking hole and having the other side supported by the tapered part of the bolt and the tapered part of the washer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tap holder, and more particularly to a tap holder that can be slightly expanded and contracted in the axial direction.

  When threading, a tap holder consisting of a holder body that fits a tap collet holding a threading tap (tool) and a shank that detachably attaches the holder body to the machine tool spindle is used. Is done.

  Current machine tools synchronize spindle rotation and feed rate control. For example, synchronous control is performed so that the rotation of the main shaft and the feed speed of the main shaft are 1.27 mm per rotation from the rotation to the stop of screw machining. In a machine tool without synchronous control, when stopping the spindle, there is inertia, so the spindle stops after rotating more than the feed amount of the spindle. For this reason, the tap holder has an expansion / contraction function that expands and contracts in the axial direction in order to correct the deviation between the feed amount and the rotation.

  For this reason, it has been thought that if the machine tool is provided with synchronous control, the tap holder does not need an expansion / contraction function. However, it has become known that it is difficult to completely synchronize the rotation of the spindle and the feed speed of the spindle because a slight deviation occurs due to aging and a decrease in accuracy. That is, if a screw is processed with a tap holder that does not have the function of extending or contracting in the axial direction, the tap may be broken or the accuracy of the thread may be reduced. For this reason, there is a need for a tap holder that does not require a large amount of expansion / contraction as in the prior art, but is capable of minute expansion / contraction (0.1 to 0.5 mm) in the axial direction.

  In Patent Document 1, between the shank and the tap holder body, the tap holder body is urged in opposite directions in the axial direction, and the extension spring and the contraction are brought into a state where the tap holder is stopped at a position where the urging forces are balanced. A tap holder is provided with a spring that, when a spindle feed error occurs during tapping and the feed amount and tap pitch do not match, reacts to external force from the tap and slides in the direction to match the tap pitch. ing. However, the structure is complicated, such as requiring an extension spring and a contraction spring.

JP 2004-142033 A

  An object of the present invention is to provide a tap holder that is simple in structure, can adjust the amount of expansion and contraction, has no backlash in the axial direction and the rotational direction, and can be slightly expanded and contracted in the axial direction.

  A tap holder according to the present invention includes a shank having a cylindrical portion provided with a plurality of through holes in the circumferential direction, and is slidably fitted to the outside of the cylindrical portion, and is locked at a position corresponding to the through hole. A holder main body having a hole formed therein, a bolt housed in the cylindrical portion, having a head portion and a shaft portion, and having a tapered portion formed on the lower side of the head portion, and extrapolated to the shaft portion of the bolt A washer having a tapered portion formed toward the head of the bolt, a nut screwed into the screw tip of the bolt, and an extrapolated portion of the shaft of the bolt, with one end abutting against the washer The other end is accommodated in the through hole, the one side is supported by the circumferential portion of the locking hole, and the other side is the tapered portion of the bolt and the tapered portion of the washer. A steel ball to be supported, the shank and the holder body When an external force that relatively shifts between them is applied, the locking hole is displaced in the axial direction and pushes the steel ball toward the bolt side, and the steel ball makes the taper portion of the bolt and the taper portion of the washer even. The coil spring is pressed to compress the coil spring.

  A bolt adjusting screw is provided that is screwed into the shank and adjusts a gap between the bolt head and limits a movable range of the bolt.

  The holder main body is characterized in that a recess is formed in the periphery of the locking hole.

  According to the tap holder according to the present invention, (1) the structure is simple and chemical resistant because it is slightly expanded and contracted by a single spring and steel ball sandwiched between a washer and a nut on the shaft of a bolt mounted on the shank. It can be made excellent in oil resistance, heat resistance, durability and deformation resistance. (2) Since the nut to be screwed into the screw tip portion of the bolt is provided, the force applied to the winding spring can be adjusted in advance by moving the nut up and down. For example, if the amount of compression of the winding spring is increased, the force that causes the holder body to shift with respect to the shank can be increased. Conversely, if the amount of compression of the winding spring is decreased, the force that causes the holder body to shift with respect to the shank. Can be reduced. (3) Since the steel ball partially falls into the locking hole of the holder body and is supported by the circumferential portion of the locking hole, the steel ball can be free of rattling. (4) When the holder body is displaced with respect to the shank, the locking hole of the holder body moves, the steel ball is pushed out to the bolt side, and the steel ball presses the taper part of the bolt and the taper part of the washer evenly. By compressing the spring, the holder body can be slightly expanded and contracted. The microscopic expansion and contraction of the holder body can improve the thread processing accuracy without excessive threading and prevent the tap from being damaged.

  According to claim 2, since the bolt adjusting screw is provided in the shank, the movable range of the bolt can be limited by adjusting the gap with the bolt head, and the amount of expansion and contraction can be made variable. According to the third aspect, since the concave portion dug down from the inner peripheral surface is provided around the locking hole, the steel ball can be received at a deep position of the locking hole and stably held.

It is an axial sectional view of the tap holder according to the present invention. It is a fragmentary perspective view which shows the circumference | surroundings of the locking hole of FIG. It is AA sectional drawing of FIG. It is a fragmentary perspective view at the time of providing a counterbore around a locking hole. It is explanatory drawing when the force which shifts between a shank and a holder main body acts in the tap holder by this invention. (A) shows a normal state. (B) shows the case where the holder body slides slightly downward. (C) shows the case where the holder body slides slightly upward.

  Hereinafter, the tap holder of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an axial sectional view of a tap holder according to the present invention. As shown in FIG. 1, the tap holder 100 includes a holder body 2 to which a shank 1 and a tap collet 25 are coupled. The shank 1 is composed of a truncated cone 27 coupled to a main shaft 26 of a machine tool and a cylindrical portion 15 in which a plurality of through holes 17 are arranged in the circumferential direction. The holder body 2 is connected to the tap collet 25 and is slidably fitted to the outside of the cylindrical portion 15 of the shank 1. The holder main body 2 has a locking hole 18 formed at a position corresponding to the through hole 17 of the shank 1.

  The bolt 6 is housed in the cylindrical portion 15 of the holder body 2. The bolt 6 has a head portion 6a and a shaft portion 6b. A tapered portion 11 is formed below the head portion 6a. The washer 3 is extrapolated to the shaft portion 6 b of the bolt 6 and is housed inside the cylindrical portion 15 of the shank 1. The washer 3 is formed with a tapered portion 12 toward the head 6 a of the bolt 6. The nut 7 is screwed into the screw tip 6 c of the bolt 6 and is housed in the cylinder of the shank 1. The height with the washer 3 can be adjusted by turning the nut 7. Thereby, the compression amount of the winding spring 4 can be changed, and the force given to the winding spring 4 beforehand can be adjusted. The nut 7 is fixed to the bolt 6 with a set screw 9 after height adjustment. The winding spring 4 is extrapolated to the shaft portion 6 b of the bolt 6, one end is in contact with the washer 3, and the other end is in contact with the nut 7. The steel ball 20 is accommodated in the through-hole 17 of the shank 1, one side is supported by the locking hole 18 of the holder body 2, and the other side is formed by a tapered portion 11 of the bolt 6 and a tapered portion 12 of the washer 3. Supported by a groove.

  The bolt adjusting screw 22 is adjusted so that a gap is formed between the lower side and the head 6 a of the bolt 6, and the upper side is screwed into the inner peripheral portion of the truncated cone 27 of the shank 1 and fixed by the set screw 10. The movable range of the bolt 6 can be limited by turning the bolt adjusting screw 22, and the “sliding amount” of the shank cylindrical portion 15 and the holder body 2 can be adjusted.

  There is a space between the screw-side end face of the bolt 6 and the bottom of the cylindrical portion of the holder body 2, and the nut 7 can be moved up and down relatively by turning the bolt 6, and the set length of the winding spring 4 can be adjusted.

  FIG. 2 is a partial perspective view showing the periphery of the locking hole 18 of the holder body 2. 3 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 2 and 3, the inner diameter of the locking hole 18 of the holder body 2 is smaller than the outer diameter of the steel ball 20. Further, a part of the steel ball 20 falls into the locking hole 18, and the steel ball 20 is supported in line contact with the circumferential portion of the locking hole 18. For this reason, attachment without play can be performed. Around the locking hole 18, a recess 14 is formed that is dug down outside the inner peripheral surface of the holder body 2. The recess 14 is provided in an annular shape along the inner periphery of the holder body 2 and serves as a guide groove when the steel ball 20 is introduced from a mounting hole (not shown). As shown in FIG. 3, if the holder body 2 moves upward, for example, the steel ball 20 is shifted to the right in FIG. 3. Even if the holder body 2 moves downward, the steel ball 20 is shifted to the right in FIG.

  FIG. 4 is a partial perspective view when a counterbore 19 is provided around the locking hole 18. A counterbore 19 may be provided instead of the recess 14. According to the recess 14 or the counterbore 19, the steel ball 20 can be received at a deep position and stably held without increasing the diameter of the locking hole 18.

  FIG. 5 is an explanatory view when a force for shifting between the shank and the holder body is applied in the tap holder according to the present invention. FIG. 5A shows a normal state. FIG. 5B shows a case where the holder main body is slid slightly. FIG. 5C shows a case where the holder body slides slightly upward. When a force that relatively shifts between the shank 1 and the holder body 2 is applied, even if the holder body 2 of FIG. 5B extends away from the shank 1, the holder of FIG. Even when the main body 2 shrinks so as to approach the shank 1, the steel ball 20 is pushed out in the direction in which the bolt 6 is present because the locking hole 18 is displaced in the axial direction.

  The extruded steel ball 20 presses the tapered portion 11 of the bolt 6 and the tapered portion 12 of the washer 3 evenly, thereby compressing the winding spring 4 and expanding the gap between the washer 3 and the bolt 6 to the winding spring 4. give. At this time, since the bolt 6 can move by the set gap S between the bolt 6 and the bolt adjusting screw 22, the amount of displacement between the shank 1 and the holder main body 2 is similarly limited.

  When the force that relatively shifts between the shank 1 and the holder main body 2 is lost, the winding spring 4 pushes back the nut 7 and the washer 3, so that the steel ball 20 is restored to its original position. That is, when the bolt 6 and the washer 3 are pushed back by the winding spring 4, the taper portion 11 of the bolt 6 and the taper portion 12 of the washer 3 push the steel ball 20 back toward the locking hole 18. In this way, the steel ball 20 is restored to the original position.

  A steel ball 21 is provided so that the shank 1 and the holder body 2 are not displaced from each other in the rotational direction. The steel ball 21 is mounted in a recessed hole formed by the hole of the shank 1 and the hole of the holder main body 2, and restricts the movement of the shank 1 and the holder main body 2.

  The tap holder 100 according to the present invention can be slightly slid by one winding spring, and the operating load and the sliding amount can be adjusted. Further, since the steel balls 20 between the shank 1 and the holder body 2 are stably supported by the locking holes 18, there is no backlash in the rotational direction of the shank 1 and the holder body 2.

  According to the present invention, it is suitable as a tap holder that has a simple structure and can be expanded and contracted minutely.

DESCRIPTION OF SYMBOLS 1 Shank 2 Holder body 3 Washer 4 Winding spring 6 Bolt 6a Head 6b Shaft part 6c Screw tip part 7 Nut 9, 10 Set screw 11 Tapered part (bolt side)
12 Taper (washer side)
DESCRIPTION OF SYMBOLS 14 Recessed part 15 Cylindrical part 17 Through-hole 18 Locking hole 18a Circumferential part 19 Counterbore 20, 21 Steel ball 22 Bolt adjustment screw 25 Tap collet 26 Spindle 27 Frustum 100 Tap holder

Claims (3)

A shank having a cylindrical portion provided with a plurality of through holes in the circumferential direction;
A holder body that is slidably fitted to the outside of the cylindrical portion, and has a locking hole formed at a position corresponding to the through hole;
A bolt housed in the cylindrical portion, having a head portion and a shaft portion, and having a tapered portion formed on the lower side of the head portion;
A washer that is extrapolated to the shaft of the bolt and has a tapered portion formed toward the head of the bolt;
A nut that is screwed into the screw tip of the bolt;
A winding spring that is extrapolated to the shaft of the bolt, one end is in contact with the washer, and the other end is in contact with the nut;
A steel ball accommodated in the through hole, one side supported by a circumferential portion of the locking hole, and the other side supported by a taper portion of the bolt and a taper portion of the washer;
When an external force that relatively shifts between the shank and the holder body is applied, the locking hole is displaced in the axial direction to push the steel ball toward the bolt side, and the steel ball is in contact with the taper portion of the bolt and the bolt. A tap holder that compresses the winding spring by uniformly pressing a tapered portion of a washer.
2. The bolt adjustment screw according to claim 1, further comprising: a bolt adjusting screw that is screwed into the shank and adjusts a gap between the bolt head and restricts a movable range of the bolt. Tap holder.
  The tap holder according to claim 1, wherein the holder body is formed with a recess dug down from an inner peripheral surface around the locking hole.

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