Bit retention assembly for rotary hammer

Patent metadata

Field	Value
Publication number	US-11007631-B2
Application number	US-201414155767-A
Country	US
Kind code	B2
Filing date	Jan 15, 2014
Priority date	Jan 15, 2014
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A bit retention assembly, for securing a tool bit to a spindle of a rotary hammer, includes a plurality of detent members movable in unison from a locking position to an insertion position in response to insertion of the tool bit within the spindle, a biasing member configured to bias the detent members toward the locking position, and a collar movable along the spindle between a first axial position and a second axial position. The collar has an annular wall at least partially defining a pocket. A first end of the biasing member is received within the pocket when the detent members are in the locking position such that the first end of the biasing member is radially constrained by the annular wall.

First claim

What is claimed is:

1. A rotary hammer adapted to impart axial impacts to a tool bit, the rotary hammer comprising:
a motor;
a spindle coupled to the motor for receiving torque from the motor, the spindle including a first retaining groove and a second retaining groove spaced from the first retaining groove;
a piston at least partially received within the spindle for reciprocation therein;
an anvil received within the spindle for reciprocation in response to reciprocation of the piston, the anvil imparting axial impacts to the tool bit in response to reciprocation of the piston;
a bit retention assembly for securing the tool bit to the spindle, the bit retention assembly including
a plurality of detent members movable rearward in unison from a forwardmost locking position to a rearmost insertion position in response to insertion of the tool bit within the spindle,
a biasing member configured to bias the detent members toward the locking position,
a collar movable along the spindle in an axial direction between a first axial position and a second axial position, the collar having an annular wall at least partially defining a pocket, and
a ring insert molded with the collar such that the ring is fixed within the pocket;

wherein an inner surface of the ring radially constrains the detent members when the detent members are in the locking position and the collar is in the first axial position;
wherein a first end of the biasing member is received within the pocket when the detent members are in the locking position such that the first end of the biasing member is radially constrained by the annular wall;
a first retaining ring received within the first retaining groove of the spindle and engageable with the collar to prevent axial movement of the collar past the first axial position;
a cap located at a front end of the spindle, the cap including a front portion defining a hole through which the tool bit extends when the tool bit is inserted within the spindle and a rear portion with a projection having a substantially rounded profile in the axial direction; and
a second retaining ring received within the second retaining groove of the spindle, the second retaining ring configured to engage the projection to retain the cap on the spindle,
wherein the cap is removable from the spindle,
wherein the first retaining ring is configured to prevent axial movement of the collar past the first axial position when the cap is removed from the spindle, and
wherein the projection of the cap is positioned between the first retaining ring and the second retaining ring when the cap is retained on the spindle.

2. The rotary hammer of claim 1 , wherein the spindle includes
a receptacle in which the tool bit is received, and
a plurality of slots extending between an exterior of the spindle and the receptacle, each of the slots receiving a corresponding one of the plurality of detent members therein.

3. The rotary hammer of claim 2 , wherein each of the slots has an included slot angle between about 30 degrees and about 90 degrees.

4. The rotary hammer of claim 3 , wherein each of the slots has an included slot angle of about 60 degrees.

5. The rotary hammer of claim 2 , wherein the spindle further includes a pair of keys projecting inwardly into the receptacle, and wherein the tool bit includes a pair of axially-extending keyways that slidably receive the keys when the tool bit is inserted within the spindle.

6. The rotary hammer of claim 5 , wherein the tool bit further includes a plurality of indentations, each of the indentations receiving a corresponding one of the plurality of detent members therein when the tool bit is inserted within the spindle and when the detent members are in the locking position.

7. The rotary hammer of claim 6 , wherein torque is transferred from the spindle to the tool bit through the keys and through the detent members.

8. The rotary hammer of claim 1 , wherein the plurality of detent members comprises two opposed balls.

9. The rotary hammer of claim 1 , wherein the bit retention assembly further includes
a washer disposed between the first end of the biasing member and the plurality of detent members,
wherein the washer includes a tapered inner portion that engages the detent members to bias the detent members toward the locking position.

10. The rotary hammer of claim 9 , wherein the washer includes a generally flat outer periphery, wherein the outer periphery of the washer contacts the ring when the detent members are in the locking position, and wherein the outer periphery of the washer is spaced from the ring to form a gap in which at least a portion of the detent members are received when the detent members are in the insertion position.

11. The rotary hammer of claim 9 , wherein the washer further includes a circular aperture through which the spindle extends.

12. The rotary hammer of claim 11 , wherein the tapered inner portion has a frustoconical shape that is substantially uniform in a circumferential direction.

13. The rotary hammer of claim 1 , wherein the detent members are movable from the locking position to a release position in response to a removal force being applied to the tool bit when the collar is in the second axial position.

14. The rotary hammer of claim 1 , wherein the spindle is made of material hardened by a carbonitriding process.

15. The rotary hammer of claim 1 , further comprising a striker received within the spindle for reciprocation in response to reciprocation of the piston, wherein the anvil is positioned between the striker and the tool bit.

16. The rotary hammer of claim 1 , wherein the biasing member is a coil spring.

17. The rotary hammer of claim 1 , wherein the spindle includes a shoulder, and wherein a second end of the biasing member bears against the shoulder.

18. A rotary hammer adapted to impart axial impacts to a tool bit, the rotary hammer comprising:
a motor;
a spindle coupled to the motor for receiving torque from the motor, the spindle including a first retaining groove and a second retaining groove spaced from the first retaining groove;
a bit retention assembly for securing the tool bit to the spindle, the bit retention assembly including
a plurality of detent members movable rearward from a locking position to an insertion position in response to insertion of the tool bit within the spindle,
a biasing member configured to bias the detent members toward the locking position,
a collar movable along the spindle in an axial direction between a first axial position and a second axial position, and
a ring fixed to the collar, wherein an inner surface of the ring radially constrains the detent members when the detent members are in the locking position and the collar is in the first axial position;

a first retaining ring received within the first retaining groove of the spindle and engageable with the collar to prevent axial movement of the collar past the first axial position;
a cap located at a front end of the spindle, the cap including a front portion defining a hole through which the tool bit extends when the tool bit is inserted within the spindle and a rear portion with a projection having a substantially rounded profile in the axial direction; and
a second retaining ring received within the second retaining groove of the spindle, the second retaining ring configured to engage the projection to retain the cap on the spindle,
wherein the cap is removable from the spindle,
wherein the first retaining ring is configured to prevent axial movement of the col

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Didier Will
• Ludy Benjamin J

Classifications

• Y10T279/17521

  Reciprocating cam sleeve · CPC title

• B25D2217/0042

  Ball-shaped locking members · CPC title

• B25D17/088 Primary

  with radial movable locking elements co-operating with bit shafts specially adapted therefor · CPC title

• B25D16/00

  Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)} · CPC title

• B25D2217/003

  Details relating to chucks with radially movable locking elements · CPC title