Title: Drill-chuck jaw with hard-metal inserts
Abstract: A drill-chuck jaw hag an elongated metal body formed with a toothed back face and an opposite front face. The body is generally symmetrical to a longitudinal plane bisecting the back and front faces. A pair of hard-metal insert parts fixed to the front face are each formed with a projecting linear edge extending longitudinally parallel to but offset from the plane. The edges symmetrically flank the plane.
Patent Number: 6,883,808 Issued on 04/26/2005 to Rohm, et al.
| Inventors:
|
Rohm; Gunter Horst (Sontheim, DE);
Mack; Hans-Dieter (Sontheim, DE)
|
| Assignee:
|
Rohm GmbH (Sontheim, DE)
|
| Appl. No.:
|
303619 |
| Filed:
|
November 25, 2002 |
Foreign Application Priority Data
| Nov 24, 2001[DE] | 101 57 705 |
| Current U.S. Class: |
279/60; 279/62; 279/152 |
| Intern'l Class: |
B23B 031//10 |
| Field of Search: |
279/60- 65,123,152,153
|
References Cited [Referenced By]
U.S. Patent Documents
| 1633828 | Jun., 1927 | Sloan.
| |
| 3558146 | Jan., 1971 | Mayers et al.
| |
| 4097054 | Jun., 1978 | Derbyshire.
| |
| 4752165 | Jun., 1988 | Wanner.
| |
| 5340128 | Aug., 1994 | Weiss et al.
| |
| 6427555 | Aug., 2002 | Mack.
| |
| 6648341 | Nov., 2003 | Gaddis et al.
| |
| 2003/0066390 | Apr., 2003 | Mack.
| |
| Foreign Patent Documents |
| 3122876 | Dec., 1982 | DE.
| |
| 3443186 | May., 1986 | DE.
| |
| 3644707 | Jul., 1988 | DE.
| |
| 29922011 | Feb., 2000 | DE.
| |
| 370963 | Apr., 1932 | GB.
| |
Primary Examiner: Howell; Daniel W.
Attorney, Agent or Firm: Dubno; Herbert, Wilford; Andrew
Claims
1. A drill-chuck jaw comprising:
an elongated metal body formed with a toothed back face and an opposite front
face, the body being generally symmetrical to a longitudinal plane bisecting the
back and front faces; and
a pair of hard-metal insert parts permanently fixed to the front face and each
formed with a projecting linear edge extending longitudinally parallel to but offset
from the plane, the edges symmetrically flanking the plane.
2. The drill-chuck jaw defined in claim 1 wherein each of the edges is formed
with at least one crosswise and forwardly open notch.
3. The drill-chuck jaw defined in claim 1 wherein each of the edges has beveled ends.
4. A drill-chuck jaw comprising:
an elongated metal body formed with a toothed back face and an opposite front
face, the body being generally symmetrical to a longitudinal plane bisecting the
back and front faces; and
a pair of hard-metal insert parts fixed to the front face and each formed with
a projecting linear edge extending longitudinally parallel to but offset from the
plane, the edges symmetrically flanking the plane and having rounded ends.
5. A drill-chuck jaw comprising:
an elongated metal body formed with a toothed back face and an opposite front
face, the body being generally symmetrical to a longitudinal plane bisecting the
back and front faces, the front face having a pair of planar facets extending at
an obtuse angle to each other; and
a pair of hard-metal insert parts fixed to the front face and each formed with
a projecting linear edge extending longitudinally parallel to but offset from the
plane, the edges symmetrically flanking the plane.
6. A drill-chuck law comprising:
an elongated metal body formed with a toothed back face and an opposite front
face, the body being generally symmetrical to a longitudinal plane bisecting the
back and front faces, the front face being formed with a groove in which the insert
parts are set; and
a pair of hard-metal insert parts fixed to the front face and each formed with
a projecting linear edge extending longitudinally parallel to but offset from the
plane, the edges symmetrically flanking the plane.
7. The drill-chuck jaw defined in claim 6 wherein the insert parts are longitudinally
offset from each other in the groove.
8. The drill-chuck jaw defined in claim 6 wherein the insert parts are transversely
adjacent each other in the groove.
9. A drill-chuck law comprising:
an elongated metal body formed with a toothed back face and an opposite front
face, the body being generally symmetrical to a longitudinal plane bisecting the
back and front faces; and
a pair of hard-metal insert parts fixed to the front face and each formed with
a projecting linear edge extending longitudinally parallel to but offset from the
plane, the edges symmetrically flanking the plane at a spacing of at most 0.75
mm.
10. The drill-chuck jaw defined in claim 1 wherein the insert parts are welded
to the bodies.
11. The drill-chuck jaw defined in claim 4 wherein each of the edges is formed
with at least one crosswise and forwardly open notch.
12. The drill-chuck jaw defined in claim 5 wherein each of the edges is formed
with at least one crosswise and forwardly open notch.
13. The drill-chuck jaw defined in claim 5 wherein each of the edges has beveled ends.
14. The drill-chuck jaw defined in claim 6 wherein each of the edges is formed
with at least one crosswise and forwardly open notch.
15. The drill-chuck jaw defined in claim 6 wherein each of the edges has beveled ends.
16. The drill-chuck jaw defined in claim 9 wherein each of the edges is formed
with at least one crosswise and forwardly open notch.
17. The drill-chuck jaw defined in claim 9 wherein each of the edges has beveled ends.
Description
FIELD OF THE INVENTION
The present invention relates to drill-chuck jaw. More particularly this invention
concerns such a jaw with hard-metal inserts.
BACKGROUND OF THE INVENTION
A standard drill chuck has a body centered on and rotatable about an axis and
formed
with a plurality of axially extending angled guides angularly spaced about the
axis. Respective jaws in these guides can be moved between a forward holding position
in which they grip a tool and a rear releasing position. Screwthread formations
on back edges of the jaws mesh with a threaded sleeve that is rotated relative
to the chuck body to advance and retract the jaws. Alternately the guides are formed
in a sleeve that rotates relative to the chuck body and the screwthread formations
on the jaws mesh with a screwthread on the body for similar action.
Even though the jaws are made of steel, they are typically used to grip tools
of similar hardness. Thus it is known to provide special hard-metal, e.g. carbide,
inserts in the gripping faces of the jaws to reduce wear of the jaws and thereby
prolong the life of the drill or lathe carrying the chuck. This is particularly
the case for a hammer drill where the tool is also moved axially as it is rotated.
Such inserts must be mounted very, very solidly on the chuck jaw. Once installed
they must be able to withstand considerable lateral forces as the chuck applies
torque to the tool, and they must hold even when the entire tool gets fairly hot
as is common in machining.
The typical chuck can hold a tool between 1.0 mm and 10.0 mm in diameter, and
typically is set to go down to 0.8 mm so that when worn it can still hold a 1.0
mm bit. This can be done with standard chuck jaws by forming their front faces
with a small groove, but the typical carbide insert is produced by sintering and
cannot be given the desired shape, at least not with a groove of small radius of
curvature. Thus it in not possible with insert-type jaws to provide the desired
small clearance.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved drill-chuck
jaw with a hard-metal insert.
Another object is the provision of such an improved drill-chuck jaw with
a hard-metal insert which overcomes the above-given disadvantages, that in which
can have the desired small clearance, even though provided with hard-metal inserts.
SUMMARY OF THE INVENTION
A drill-chuck jaw has according to the invention an elongated metal body formed
with a toothed back face and an opposite front face. The body is generally symmetrical
to a longitudinal plane bisecting the back and front faces. A pair of hard-metal
insert parts fixed to the front face are each formed with a projecting linear edge
extending longitudinally parallel to but offset from the plane. The edges symmetrically
flank the plane.
Such a jaw is particularly suited for use in a hammer drill and has the considerable
advantage that the spacing of the actual holding edges can be reduced to a much
smaller distance than in jaws with standard carbide inserts. The spacing of the
holding edges, which can be smaller than 0.75 mm measured perpendicular to the
jaw symmetry plan, and the depth of the groove formed between them can be set at
any useable dimension without running up against machining problems. All that is
necessary is to properly position the insert parts on the jaw body when welding
them in place. The actual construction of the insert parts is simple and standard.
According to the invention each of the edges is formed with at least one
crosswise and forwardly open notch. Such a notch reduces the length of the gripping
edge so that, with the same gripping force, more pressure is brought to bear per
unit of area on the shank of the tool held by the jaw. In addition each of the
edges can have beveled or rounded ends. This further aids the jaw edges in biting
into the tool shank. The rounded or beveled ends prevent the jaw edges from biting
in and forming barbs, in particular during hammer drilling.
The front jaw face according to the invention has a pair of planar facets extending
at an obtuse angle to each other. In addition this front face is formed with a
groove in which the insert parts are set. The insert parts can be parts longitudinally
offset from each other in the groove or transversely adjacent each other in the groove.
BRIEF DESCRIPTION OF THE DRAWING
The above ad other objects, features, and advantages will become more readily
apparent from the following description, reference being made to the accompanying
drawing in which:
FIG. 1 is a front view of a first drill-chuck jaw according to the invention;
FIG. 2 is a section along line II—II of FIG. 1;
FIG. 3 is a front view of a second jaw in accordance with the invention;
FIG. 4 is a front view of a third jaw according to the invention;
FIG. 5 is an and view of the jaw of FIG. 4;
FIG. 6 is a front view of a fourth jaw;
FIGS. 7 and 8 are side views of inserts according to the invention; and
FIG. 9 is an end view of the jaws of FIG. 1 installed in a drill chuck.
SPECIFIC DESCRIPTION
As seen in the drawing, a drill-chuck jaw
1 has an elongated body formed
as a steel bar or rod having a back face formed with a row of teeth
3 (FIG.
9 only) and a front face
4 here formed by a pair of planar facets extending
at an angle of 120° from each other and angled symmetrically away from a central
symmetry plane
5 of the body
2. This plane
5 runs through
a longitudinal axis
2A of the body
2 and the face
4 extends
at an angle to this axis
2A. The face
4 here is formed with a rectangular
section groove
6 that extends along the face
4 and that is centered
on the symmetry plane
5. This structure is substantially identical for all
embodiments of the invention.
In the arrangement of FIGS. 1 and 2 the groove
6 holds an insert
7
formed by two identical but separate carbide bars or parts
8 that symmetrically
flank the plane
5 and that in fact bear on each other at the plane
5.
Each bar
8 is formed with a longitudinally extending linear ridge or edge
9 so that the two edges
9 symmetrically flank this plane
5.
In the arrangement of FIG. 3 there are two longitudinally spaced inserts
7a
each formed by a pair of short parts
8a substantially identical
to the parts
8 of FIG. 1, but shorter.
FIGS. 4 and 5 show an arrangement similar to that of FIGS. 2 and 3, but here
each of the two axially spaced inserts
7b are formed by a single
bar
8b. These barn
8b are identical, but are oppositely
mounted in the groove
6 so that the ridge or edge
9 of one of the
bars
8b is to one side of the plans
5 and that of the other
is to the other side. FIG. 6 shows a similar arrangement, but where two slightly
longer bars
8c axially abut each other and form an insert
7c.
Once again the bars
8c are oppositely mounted so the edges
9
symmetrically flank the plane
5.
FIG. 7 shows an insert
7d having a bar
8d formed
with a pair of crosswise notches
10 interrupting the edge
9 that
allows the insert
7d to clamp with great force. Corners
14
of this bar
8d are rounded, and welds
15 secure it in place
in the groove
6. In FIG. 8 an insert
7a has a bar
8e
formed with a single relief notch
10, and has corners
16 that
are chamfered or beveled.
FIG. 9 shows how three jaws
1 such as shown in FIGS. 1 and 2 are pressed
together at an axis
13 so that angled facets or faces
11 and
12
of the bars
7 sit flatly against each other, to which end they extend at
angles of 120° to each other. It is therefore possible for a very small bit
shank to be held by the six edges
9. In addition the facets
11 and
12 engage each other before the edges
9 do, so that these edges
9
are not damaged by engagement with each other.
*
