Cutters – for shaping – Including cut off tool
Reexamination Certificate
1999-10-18
2001-05-22
Wellington, A. L. (Department: 3722)
Cutters, for shaping
Including cut off tool
C407S110000, C407S050000, C407S072000, C083S845000
Reexamination Certificate
active
06234727
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a resilient clamping mechanism for an insert-receiving pocket of a cutting tool.
BACKGROUND OF THE INVENTION
Cutting tools employing a resilient clamping mechanism for clamping cutting inserts are generally of relatively narrow thickness. For example, cutting operations such as grooving and parting off can be performed by a cutting insert retained in an insert pocket located between the clamping surfaces of upper and lower jaws of a relatively narrow holder blade. The holder blade is, in turn, generally clamped in a blade-retaining block. The holder blade is generally provided with a suitably designed opening, in the vicinity of the insert pocket whereby a relatively narrow bridging portion is formed enabling a limited degree of resilient displacement of one of the holder blade's jaws relative to the other. Generally, the lower jaw is rigid and the upper jaw is resiliently displaceable. The opening can be of the form of an aperture, or a slot, or a slot terminating in an aperture. Examples of such cutting tools are disclosed in U.S. Pat. No. 3,785,021 and U.S. Pat. No. 4,580,930. A rotary slot-cutting tool employing a resilient insert clamping mechanism is disclosed in U.S. Pat. No. 5,059,068. The cutter body is disc-shaped and of relatively narrow thickness, with cutting insert pockets located around its periphery. As with the holder blade, an insert pocket has two jaws between which an insert is clamped by means of the resilient force resulting from the bending of the clamping jaw.
Whether the cutting tool is a holder blade or a rotary slot cutting tool, the bending of the clamping jaw is obtained by manufacturing the insert pocket such that the distance between the clamping surfaces of the jaws is smaller than the height of the portion of the insert located between the clamping surfaces. Consequently, when an insert is located in the insert pocket, the clamping jaw is held in a bent position creating an elastic force by means of which the insert is clamped in position.
A well-known disadvantage of this form of clamping mechanism is the instability of the clamped cutting insert in certain cutting tools and under certain cutting conditions. In rotary slot cutting tools, each individual cutting insert intermittently makes contact with a workpiece as the tool rotates about its axis of rotation. As a result a cutting insert suffers a blow each time it hits the workpiece and is likely to be displaced due to a diminishing of the clamping force. If only some of the inserts are so displaced, or they are displaced by different radial distances, then the undisplaced ones, or the less displaced ones, will stop participating in the slotting operation causing uneven wear of the inserts. Instability of the cutting insert also arises in the use of inserts retained in holder blades in, for example, grooving operations. When the holder blade is pulled out from a completed groove the insert can be accidentally be pulled out of the holder blade.
A solution to this problem is proposed in U.S. Pat. No. 5,743,680 which discloses a specially designed cutting insert and a correspondingly specially designed insert pocket in the holder blade. Similarly, a solution to the problem of insert instability in rotary slot cutting tools is proposed in U.S. Pat. No. 5,059,068 in which specially designed inserts and correspondingly specially designed insert pockets in the cutter body are disclosed.
It is the object of the present invention to provide a resilient clamping mechanism for insert, which, inter alia, overcomes the aforementioned problem of possible displacement of an insert in a reliable and novel manner.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided for use in a cutting tool, the cutting tool comprising a body portion and a clamping portion, a cutting insert clamping mechanism comprising:
a base jaw;
a clamping jaw having an upper side and a lower side, the base jaw and the clamping jaw having a gap between them forming an insert receiving pocket;
an aperture extending in a generally upward and forward direction from a rear upper section of the insert receiving pocket;
a first narrow bridge section connecting the clamping jaw to the body portion of the cutting tool; and
a second narrow bridge section extending generally towards the second clamping surface.
In accordance with one embodiment of the invention, the lower side of the clamping jaw comprises a forward first clamping surface separated by a recess from a rearward second clamping surface.
Typically, the first narrow bridge section is situated generally between the aperture and the upper side of the clamping jaw.
Further typically, the second narrow bridge section is generally situated between the recess and the aperture.
Preferably, the forward portion of the aperture is located further forward than the second clamping surface.
In accordance with the present invention, a first resilience axis of rotation is associated with the first narrow bridge section and a second resilience axis of rotation is associated with the second narrow bridge section.
Generally, a first clamping force is associated with the first clamping surface and a second clamping force is associated with the second clamping surface.
Preferably, the first clamping force is independent of the second clamping force.
In accordance with one specific embodiment of the invention, an elongated slot extends from a rear section of the aperture in a generally rearward direction into a connecting block and a clamping screw extends downwards in the connecting block across the elongated slot.
If desired, the insert receiving pocket is provided with an aperture for receiving an insert-removing device, the aperture extending from a rear section of the insert receiving pocket in a generally rearward direction.
Further if desired, a rear section of the insert receiving pocket is provided with a protuberance extending from the body portion of the cutting tool, the protuberance having a front side constituting an insert location surface.
Still further if desired, the clamping jaw of the cutting insert clamping mechanism further comprises a front side intermediate between the upper and lower sides thereof, the front side constituting an insert location surface.
In accordance with one application, the cutting tool is a rotary slot cutting tool.
In accordance with another application, the cutting tool is a lathe tool with a body portion comprising a holder blade.
If desired, a cutting insert retained in the insert receiving pocket comprises an upper abutting surface and a lower abutting surface, the upper abutting surface comprising a forward first abutting surface separated by an upper surface recess from a rearward second abutting surface.
In accordance with one specific embodiment, the rearward second clamping surface of the lower side of the clamping jaw abuts a rear region of the upper surface recess of the cutting insert retained in the insert receiving pocket.
In accordance another embodiment of the invention, the lower side of the clamping jaw is not provided with a recess. In accordance with this embodiment a cutting insert provided with an upper surface recess in its upper abutting surface is used in the cutting tool.
In accordance with this embodiment, the lower side of the clamping jaw abuts the forward first abutting surface and the rearward second abutting surface at a forward first clamping region and rearward second clamping region, respectively.
Generally, a first clamping force is associated with the forward first clamping region and a second clamping force is associated with the rearward second clamping region.
If desired, the first clamping force can be arranged to be independent of the second clamping force.
REFERENCES:
patent: 3785021 (1974-01-01), Norgren
patent: 4580930 (1986-04-01), Zinner
patent: 5035545 (1991-07-01), Zinner
patent: 5059068 (1991-10-01), Scott
patent: 5211516 (1993-05-01), Kress et al.
patent: 5439327 (1995-08-01), Wertheim
patent: 5524518 (1996-06-01), Sundstrom
Ergenbright Erica
Iscar Ltd.
Pennie & Edmonds LLP
Wellington A. L.
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