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EP-4159347-B1 - TAP HOLDER

EP4159347B1EP 4159347 B1EP4159347 B1EP 4159347B1EP-4159347-B1

Inventors

  • IHARA, MINORU

Dates

Publication Date
20260506
Application Date
20220909

Claims (8)

  1. A tap holder (10, 100, 200), comprising: a body (11) having a collet holder hole (11b) having an opening toward distal end; a tap collet (17, 117, 217) received in the collet holder hole (11b), the tap collet (17, 117, 217) configured to advance and retract, the tap collet (17, 117, 217) having a tap mounting hole (25b) located at a distal end portion, and a sleeve hole (13e) located at a basal end portion; a torque transmission mechanism (14, 114, 214) configured to transmit rotation of the body (11) to the tap collet (17, 117, 217); a first elastic body (18, 118, 218) disposed between the body (11) and the tap collet (17, 117, 217), the first elastic body (18, 118, 218) configured to urge the tap collet (17, 117, 217) toward distal end; a sleeve (19) received in the sleeve hole (13e) and fastened to the body (11), the sleeve (19) configured to prevent the tap collet (17, 117, 217) from slipping off toward distal end; and a second elastic body (21, 121) disposed between the sleeve (19) and the tap collet (17, 117, 217), the second elastic body (21, 121) configured to urge the tap collet (17, 117, 217) toward basal end, characterized in that , the sleeve hole (13e) is a stepped through-hole, the sleeve hole (13e) has a large-diameter portion (13e2, 113e2) located at a distal end portion, and a small-diameter portion (13e1) located at a basal end portion, the sleeve (19) includes a flange (19c) having a larger diameter than the small-diameter portion (13e1), the flange (19c) disposed inside the large-diameter portion (13e2, 113e2), and a cylindrical portion (19b) received in the small-diameter portion (13e1), and the second elastic body (21, 121) is disposed between the flange (19c) and the large-diameter portion (13e2, 113e2).
  2. The tap holder (10, 100) according to claim 1, wherein the tap collet (17, 117) includes a first keyway (16, 116) located on the tap collet (17, 117), a second keyway (12) located on the collet holder hole (11b), and a key (15, 115) disposed either one of the first keyway (17, 117) and the second keyway (12) to slide the other one of the first keyway (17, 117) and the second keyway (12).
  3. The tap holder (10) according to claim 2, wherein the key (15) is a woodruff key (15) disposed in the first keyway (16).
  4. The tap holder (200) according to claim 1, wherein the torque transmission mechanism (214) includes a spline shaft (215) disposed on the tap collet (217), and a spile hole (212) located in the body (11) for the spline shaft (215) to slide.
  5. The tap holder (10, 100) according to any one of claims 1 to 4, wherein the first elastic body (18, 118) is disposed between the collet holder hole (11b) and the tap collet (17, 117).
  6. The tap holder (200) according to any one of claims 1 to 4, wherein the first elastic body (218) is disposed between a distal end surface (11f) of the body (11) and the tap collet (217).
  7. The tap holder (10, 100, 200) according to any one of claims 1 to 6, wherein the first elastic body (18, 118, 218) is an elastic ring or a disc spring.
  8. The tap holder (10, 100, 200) according to any one of claims 1 to 7, wherein the second elastic body (21, 121) is an elastic ring or a disc spring.

Description

BACKGROUND 1. Technical Field The present invention relates to a tap holder. 2. Description of the Background A proposed tap holder includes a shank, a tap holder body axially slidably received into the shank, and a first spring and a second spring disposed between the shank and the tap holder body for urging the tap holder body toward opposite direction in the axial direction to stop the tap holder body in a balanced position of the urging force (See, Japanese Patent No. 4344880). The tap holder includes an axially extending shaft member disposed on the tap holder, and a spring receiving member reciprocally disposed within the shank. The second spring urges the tap holder body in a tapping direction via the spring receiving member. The first spring is supported by the spring receiving member to urge the tap holder body in a direction opposite to the tapping direction via the shaft member. EP 2 727 676 A1 describes a tap holder configured so that the compression-side elastic characteristics and the tension-side elastic characteristics are made to be different using an elastic member for absorbing synchronization errors in the rotation and feeding of the main shaft of a machine tool. BRIEF SUMMARY The conventional tap holder has a complex structure. An object of the present invention is to provide a tap holder having a simple structure and high runout accuracy. The present invention provides a tap holder, including: a body having a collet holder hole having an opening toward distal end;a tap collet received in the collet holder hole, the tap collet configured to advance and retract, the tap collet having a tap mounting hole located at a distal end portion, anda sleeve hole located at a basal end portion;a torque transmission mechanism configured to transmit rotation of the body to the tap collet;a first elastic body disposed between the body and the tap collet, the first elastic body configured to urge the tap collet toward distal end;a sleeve received in the sleeve hole to be connected to the body, the sleeve configured to prevent the tap collet from slipping off toward distal end; anda second elastic body disposed between the sleeve and the tap collet, the second elastic body configured to urge the tap collet toward basal end. According to present invention, the sleeve hole is a stepped through-hole, the sleeve hole has a large-diameter portion located at a distal end portion, anda small-diameter portion located at a basal end portion,the sleeve includes a flange having a larger diameter than the small-diameter portion, the flange disposed inside the large-diameter portion, anda cylindrical portion received in the small-diameter portion, andthe second elastic body is disposed between the flange and the large-diameter portion. The tap holder of the present invention is used for rigid tapping. Here, the rigid tapping is a process for synchronizing the rotation and the feed of the spindle at the time of screwing. A rigid tapping may also be referred to as a synchronized tapping. The tap collet has an outer cylindrical surface that slides into the collet holder hole. The tap collet is guided by the outer cylindrical surface and the collet holder hole to move forward and backward. The tap collet includes a collet holder, a collet, and a nut. The collet holder may include a tapered hole for the collet to be mounted, a sleeve hole, and an external thread. The collet holder may further include a flange. The flange is disposed with a clear gap with a distal end surface of the body. The tapered hole may be connected to the sleeve hole. The collet has a tap mounting hole. The nut is fastened with the tap and the collet to the external thread. The body may include a shank. The body may have an internal thread. The sleeve is fixed to the internal thread. The sleeve may have a through-hole. The sleeve may be fixed to the internal thread with a bolt received in the through-hole. The key is a sliding key. Preferably, a plurality of keys are arranged. The keys are arranged rotationally symmetrically about a central axis of the body. The first elastic body is, for example, a disc spring or an elastic ring. The second elastic body is, for example, a disc spring or an elastic ring. The elastic ring has, for example, a circular or rectangular cross-sectional shape. The elastic ring is made of, for example, rubber or plastic. The first elastic body and the second elastic body are attached by being compressed more than the free length. The amount of expansion and contraction of the first elastic body and the second elastic body may be limited. For example, the first elastic body is disposed in a groove located on a basal end surface of the tap collet. The groove is, for example, a circumferential groove. The first elastic body may be disposed between a basal end surface of the flange disposed on the collet holder and a distal end surface of the body. The basal end surface of the tap collet and the basal end surface (bottom surfa