Cutting – Tool or tool with support – Cutting couple type
Reexamination Certificate
2000-03-03
2001-08-21
Rachuba, M. (Department: 3724)
Cutting
Tool or tool with support
Cutting couple type
C083S686000, C083S698910
Reexamination Certificate
active
06276247
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates generally to the field of tooling for punch presses, and more particularly to adjustable-length punch assemblies for punch presses wherein the punch assembly may be adjusted to compensate for losses in punch blade length as a result of sharpening.
B. Description of the Prior Art
In punching operations, the distance between the sharpened edge of the punch tip and the workpiece is a critical dimension. When a dulled punch tip is reground to restore a sharp edge, material loss changes this critical dimension. To account for this, adjustable punch assemblies that allow punch length adjustment have been developed.
U.S. Pat. No. 4,375,774 discloses an adjustable punch assembly wherein a punch (
12
) is carried by an axially guided punch driver (
13
), which in turn is threadably mated with a punch head or cap (
14
), whereby punch length is adjustable by rotating the punch cap relative to the punch driver. An expandable locking dowel pin (
58
) is wedged in aligned holes (
59
) in the punch cap and punch driver as a releasable locking means for preventing relative rotation between the punch cap and punch driver. The locking pin must be temporarily removed by the operator to enable length adjustment.
Another adjustable punch assembly is described in U.S. Pat. No. 5,131,303. The described punch assembly includes a punch (
20
) threadably mated with a punch driver (
10
) to enable axial length adjustment by relative rotation of the mating parts. As shown in
FIGS. 4 and 5
of this patent, a C-shaped spring clip (
30
) having a radial protrusion (
39
) at one end thereof fits within an annular groove (
31
) in the mating end of the punch driver, and protrusion (
39
) extends through a radial aperture (
33
) for receipt within a V-shaped recess
32
in the punch. The spring clip
30
is constrained in a locking position by an outer punch guide (
40
), which must be temporarily removed for sharpening and punch length adjustment.
U.S. Pat. No. 5,329,835 teaches an adjustable punch assembly having a pushbutton releasable locking means (
50
) operable along the central axis of the punch assembly. More specifically, a punch cap (
26
) is threadably mated with a tool-holding punch driver (
14
), and push button (
50
) includes four comer detents (
55
), (
57
), (
59
), and (
61
) normally engaged with four corresponding detent stops from a plurality of circumferential detent stops (
70
) in the punch cap (
26
) and also engaged with four corresponding detent stops (
55
′), (
57
′), (
59
′), and (
61
′) in the punch driver. The push button can be depressed in an axial direction against the bias of a spring to disengage the comer detents from the detent stops (
70
), thereby releasing the punch cap for adjustment rotation relative to the punch driver.
A more recent adjustable punch assembly is disclosed in U.S. Pat. No. 5,647,256. The disclosed punch assembly includes a punch cap (
28
) threadably mated with a punch driver (
18
) to permit length adjustment by rotating the parts relative to one another. A spring seat (
32
) is provided coaxially with the punch cap and punch driver adjacent the punch cap, and a releasable securing member (
38
) prevents relative rotation between the spring seat and the punch cap to indirectly prevent adjustment rotation between the punch cap and punch driver. The releasable securing member is radially depressible against a spring bias to uncouple the punch cap from the spring seat to enable adjustment rotation between the punch cap and punch driver.
The prior art adjustable punch assemblies mentioned above are complex to manufacture and/or require some disassembly to carry out length adjustment.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved punch assembly that allows a user to adjust punch length quickly and accurately to reduce set up time.
It is another object of the present invention to provide an improved punch assembly with releasable locking means for threaded punch length adjustment that is easy to manufacture and reliable over time.
In accordance with the present invention, a punch assembly comprises a guide bushing for axially guiding a punch driver carrying a punch tool, a spring tube telescopically connected to the guide bushing for axially directed movement relative thereto, a stripper spring for biasing the spring tube in an axially extended direction relative to the guide bushing, a punch cap coupled to the spring tube and threadably mated with the punch driver for adjusting axial punch length by rotation relative to the punch driver, and a releasable locking means movable between locked and unlocked positions for preventing and allowing punch length adjustment, respectively.
The punch driver includes a splined index portion having a plurality of angularly spaced grooves elongated in an axial direction, and the punch cap includes a radially extending passage opposite the splined index portion of the punch driver. In a preferred embodiment of the present invention, the releasable locking means includes a ball bearing as a locking element partially received in one of the grooves and in the passage to simultaneously engage the punch driver and the punch cap to prevent relative rotation therebetween. A plunger movable in an axial direction within a plunger channel in punch cap has an enlarged trapping portion alignable with the passage to confine the ball bearing in simultaneous engagement with the punch driver and punch cap and a reduced releasing portion alignable with the passage to permit the ball bearing to disengage from the punch driver by rolling out of the corresponding groove in the splined index portion of the punch driver. The plunger is spring-biased to reside in a locking position wherein its trapping portion is aligned with the passage to confine the ball bearing, and the plunger is manually depressible against the biasing force to a position wherein the releasing portion of the plunger is aligned with the passage.
REFERENCES:
patent: 3563124 (1971-02-01), Gargrave
patent: 4375774 (1983-03-01), Wilson et al.
patent: 5131303 (1992-07-01), Wilson et al.
patent: 5329835 (1994-07-01), Timp et al.
patent: 5647256 (1997-07-01), Schneider
patent: 5934165 (1999-08-01), Chatham
patent: 6047621 (2000-04-01), Dries et al.
Rachuba M.
Simpson, Simpson & Snyder, PLLC
Strippit Inc.
LandOfFree
Adjustable punch assembly with releasable locking does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adjustable punch assembly with releasable locking, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adjustable punch assembly with releasable locking will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2472350