Cutters – for shaping – Including holder having seat for inserted tool – With separate means to fasten tool to holder
Reexamination Certificate
2002-06-11
2004-07-06
Wellington, A. L. (Department: 3722)
Cutters, for shaping
Including holder having seat for inserted tool
With separate means to fasten tool to holder
C407S111000
Reexamination Certificate
active
06758638
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention concerns a method and holding device for the clamping of an insert into a cutting tool for metal removal machining.
2. Description of the Background Art
Many different tools are used within the metal removal machining for turning and milling. The use of tools that include a hard metal insert is previously known, e.g., a so called throw-away insert, which is clamped or locked in a tool holder. The inserts are often relatively small, usually around a maximum of ten millimeters, due to the costs of the material and of the manufacturing, and also to make it possible to gain access to and carry out confined and small machining operations on a work-piece.
Clamping of an insert into a tool holder can be achieved, for example, by the holder containing an upper and a lower adjustable locking element, into the opening of which the insert is placed, followed by the locking elements being arranged with the aid of a locking screw or similar to lock the insert firmly. A number of tools with various more or less technically complicated solutions for the arrangement for clamping into the holder are known. The adjustment and locking of the insert into the holder should be as simple as possible for reasons of efficiency. The insert must be firmly clamped. The clamping force should thus preferably be distributed over a large area. The dimensions of the holders must often be small in the vicinity of the cutting region due to the requirement of achieving good accessibility. However, the smaller the holder is, the less is the rigidity obtained in the tool.
The design of interacting, prefabricated grooves or similar on the insert and the holder is also known. The purpose of these grooves is, among other things, to give a more rigid design, to prevent sideways movement of the insert and to give simpler positioning of the insert in the holder. On the other hand, problems arise when manufacturing grooves that are to interact between the insert and the holder, since this requires complicated adjustment of tolerances and an identical grinding of the grooves in both the insert and the holder, something that of course also is expensive. The alignment of lines on two objects, during which two opposite grooves must fit into each other, places high demands on accuracy during manufacture and assembly. The problem is to obtain a correct alignment and a rigid clamping of the insert into the holder also in the locked condition. A further problem associated with prefabricated grooves of various types is that various types of inserts cannot automatically be gripped into any holder. All the different types of inserts and tool holders in which this type of clamping is to be applied, that is the alignment of lines on two objects, must be provided with equivalent grooves.
A tool for metal removal machining is previously known from U.S. Pat. No. 5,054,967 that includes a holder and an insert to be clamped in the holder. The insert can be provided with grooves, and the holder can thus be provided with matching ridges. According to another embodiment, the insert is coated on its bottom surface with a soft metal layer that has greater friction than the opposite surface in the holder with which the insert interacts. The design according to U.S. Pat. No. 5,054,967 does not specify a solution to the problems that have been described in the description of the prior art given above.
EP-A1-0802006 concerns a cutting tool that contains a holder and an insert. Sharp-edged, sharp, roof-shaped protrusions with an angle at the point of between 60° and 90° are arranged on the surfaces of the insert. The roof-shaped protrusions on the insert are pressed down into the steel surface of the tool with the aid of the pressure that loads the insert when the clamping screw is tightened, whereby the surface of the tool is plastically deformed. The design of the insert with the sharp-edged roof-shaped protrusions means that the cutting tool will “ride up on” the roof-shaped protrusions. This entails a poorer locking of the insert in the tool holder. Thus the construction according to EP-A1-0802006 does not specify a solution to the problems that have been described in the description of the prior art given above.
SUMMARY OF THE INVENTION
The intention of the present invention is to achieve the clamping of an insert in a tool holder for metal removal machining, that is both rigid and simultaneously simple and to eliminate the said disadvantages described in the description of the prior art given above. One intention is thus to achieve a method and a design that simplifies the adjustment and increases the clamping force of the insert in the tool holder. Furthermore, an intention is to create improved fixing and locking. A further intention of the present invention is to eliminate any relative motion between the insert and the holder. A further intention is a method and a design of the tool by which it is simple to exchange insert and in which many types of inserts can be used, such as insert for milling, turning, etc. A further intention is to achieve a cost-effective production of the insert and the holder.
The method and the device according to the present invention solve the above-mentioned problems, and are characterized in the said purposes by that which is made clear in the claims. Thus the method according to the present invention concerns the locking of an insert into a tool for metal removal machining. The tool comprises an insert with an upper contact surface or section and a lower contact surface or section. The insert is arranged in a holder whereby the holder comprises a holder body and a clamping device. The holder body has a lower contact surface or section. The insert is arranged such that the lower contact surface or section of the insert is brought into contact or engagement with the lower contact surface or section of the holder and the clamping device is brought into engagement with the upper contact surface or section of the insert. At least one of the contact surfaces of the insert is provided or designed with protrusions or irregularities in the form of rounded cones, teeth or the like, which are brought to press or be pressed into the opposite surface or section of the holder during deformation of the same when clamping the insert.
One advantage with this solution according to the present invention is that the clamping of the insert into the holder is significantly improved in relation to conventional methods and designs. The clamping of the insert becomes very rigid. During machining, the cutting force contributes to an increased locking of the insert into the holder. By the arrangement of the insert into the holder, the protrusions of the insert are, at least partially, or wholly, pressed into and deform the surface of the holder. This occurs during a first phase through a clamping force that is brought to act on the insert by means of a clamping device, but above all it occurs during a second phase when the cutting force acts on the insert. In this way, differences in hardness of different materials of the insert and the holder are exploited. The clamping force is distributed over a very large area, since a considerable or complete contact of surfaces is achieved along the complete surface profile of the insert. This is particularly true when the contact surface of the insert is not flat, since this then by its shape will be much longer than a flat surface. The absorption of force in all directions is achieved in the interface layer between the interacting surfaces.
Furthermore, an accurate fixing is achieved, together with an accurate locking according to the present invention. A further advantage is that no adjustment of tolerances needs to be considered during interaction between the surfaces of the insert and those of the holder. Since no complicated setting of tolerances of the surfaces of the insert and the holder take place, no problems with the adjustment of the insert arises. In this way, it is very simple and easy to exchange insert in the h
Mircona AB
Ross Dana
Ware Fressola Van der Sluys & Adolphson LLP
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