The invention relates to a cutting tool for machining workpieces by chip removal and to a distance compensating element for positioning reground cutting inserts for such a cutting tool.
A cutting tool for machining workpieces by chip removal is known from DE 197 20 836 A1. This cutting tool comprises a tool holder with a cutting insert receiving area, in which a cutting insert, in particular an indexable cutting insert, is releasably fastened using a clamping element. These cutting inserts are subjected to wear by the machining of workpieces by chip removal. Such cutting inserts, in particular indexable cutting inserts, have two or more cutting edges. By rotating the position of the cutting insert in the cutting insert receiving area, an unused cutting edge or a cutting edge in its original state can be used in each case for a subsequent machining operation. Once all of the cutting edges of the cutting insert are worn, such a cutting insert is replaced by a new cutting insert.
However, in principle, it is possible to regrind such cutting inserts. Depending on its basic shape, type of cutting and/or size, the cutting insert can be reground twice or three times, for example. This has the advantage that it is possible to save on costs compared to procuring new cutting inserts. However, when the cutting inserts are reground, the geometry of the cutting insert changes compared to the brand new or unused state. This has the disadvantage that a reliable and oriented positioning of the cutting insert in the cutting insert receiving area of the tool holder following regrinding of the cutting insert is no longer assured.
The invention is based on the object of specifying a cutting tool for machining workpieces by chip removal, and also a distance compensating element, so that reground cutting inserts can continue to be used.
This object is solved by a cutting tool in the case of which a distance compensating element is positioned at least between the reground cutting insert and the cutting insert receiving area, which distance compensating element enables correct positioning of the reground cutting insert in the cutting insert receiving area. By means of this at least one distance compensating element, material removal is compensated for during one or multiple regrinding operations of the cutting insert. This results in considerable cost savings since the regrinding of the indexable cutting inserts and the use of the distance compensating element are significantly more cost-effective than procuring a new cutting insert. Furthermore, regrinding the indexable cutting inserts contributes considerably to protecting the environment.
The distance compensating element preferably has a base body with at least one surface section which comprises a thickness that corresponds to the respective removal during one or multiple regrinding operations of the side faces of the cutting insert. In the case of a multiplicity of basic shapes of the cutting inserts, regrinding the side faces can in turn make it possible to condition the cutting edge on the cutting insert. Such a removal during the regrinding operation can comprise, for example, 0.3 mm, or 0.6 or 0.9 mm when regrinding is performed two or three times. The base body with the at least one surface section can bring about compensation, wherein the thickness of the surface section is preferably adapted to the number of regrinding operations, or to the amount removed from the side face, and corresponds thereto.
According to one preferred embodiment, the distance compensating element is configured as a flat, plate-shaped base body. This can have a rectangular, square, polygonal, oval, round, or a freely selectable contour. This enables simple production and configuration of the distance compensating element. Simple positioning of such a distance compensating element between the cutting insert and the cutting insert receiving area is also made possible.
Alternatively, the plate-shaped base body of the distance compensating element can have a curved or wavy profile along the longitudinal axis of the base body. Therefore, following the positioning of the distance compensating element between the cutting insert and the cutting insert receiving area, the distance compensating element is held under preload, thus enabling additional tolerance compensation.
The base body with the surface section preferably extends at least in part along the wall section of the cutting insert receiving area and has the same or a smaller height than the wall section of the cutting insert receiving area. As a result, the previous external geometry of the cutting tool is retained. There are no disruptive influences by the distance compensating element.
It is furthermore preferably provided that the base body with the surface section extends at least in part along the wall section of the cutting insert receiving area and has the same or a smaller length than the wall section of the cutting insert receiving area. The length of the surface section can be adapted to the respective application.
According to one further preferred configuration, it is provided that the distance compensating element, which has the base body with the at least one surface section, comprises a bearing surface section which is connected to the at least one surface section. The bearing surface section comprises a thickness that corresponds to the amount removed during single or multilayer regrinding operations of the rake surface of the cutting insert. It may be necessary in some applications to regrind the rake surface, the radius and also the side face of the cutting edge. When the rake surface is reground, the tip height of the cutting edge of the cutting insert changes after it is fixed in the cutting insert receiving area. This change in height can be compensated for by the removal of material by way of the bearing surface section on the distance compensating element.
Furthermore, the at least one surface section of the base body of the distance compensating element is preferably oriented at an angle to the bearing surface section. As a result, the distance compensating element can encompass a round cutting insert on one side or other cutting inserts at least in part on two sides. It is preferably provided that the at least one surface section of the distance compensating element is angled with respect to the bearing surface section at an angle between 40° to 90°, preferably 60° to 90°, in particular 70° to 90°. In one embodiment, the cutting insert can be placed on the distance compensating element and subsequently the distance compensating element, together with the cutting insert, can be positioned in the cutting insert receiving area in order to then fasten the distance compensating element to the gripping element. In this case, the distance compensating element is provided between the cutting insert and the cutting insert receiving area. Alternatively, it can be provided that the distance compensating element is placed on the cutting insert. In this case, the cutting insert lies directly on the cutting insert receiving area. Using a gripping and/
or clamping element, by way of the bearing surface section, the distance compensating element is held fixed with respect to the cutting insert and the cutting insert is held fixed with respect to the cutting insert receiving area. In this arrangement, the distance compensating element is positioned by the surface sections between the cutting edge and the cutting insert receiving area, and by the bearing surface section between the gripping and/or clamping element and the cutting insert.
The geometry of the bearing surface section of the distance compensating element advantageously corresponds to the basic shape or the base body of the cutting insert or is smaller. It is preferably provided that the bearing surface section of the distance compensating element covers less than 75% of the base area of the base body of the cutting insert, preferably less than 60%, in particular less than 50% of the base area of the base body of the cutting insert. The distance compensating element is preferably positioned in the cutting insert receiving area opposite the active cutting edge of the cutting insert. Improved chip removal can be achieved as a result.
It is advantageously provided that the bearing surface section of the distance compensating element has a frustoconical or circular arc-shaped contour, as seen in plan view. This contour is preferably adapted to the geometry of the cutting insert or the base area of the base body of the cutting insert. In the case of a diamond-shaped cutting insert, the bearing surface section preferably has a frustoconical configuration. In the case of a round cutting insert, the bearing surface section of the distance compensating element is preferably configured as a circular arc.
The base body of the distance compensating element with the at least one surface section and/or the bearing surface section is preferably configured as a stamped part or stamped-bent part. The base body of the distance compensating element can also be cut with a cutting jet, in particular a laser beam. In addition, a bending process can take place thereafter. This enables simple production. The material thicknesses for the base body are selected according to the amount of material removed by the regrinding operation, in order to create this distance compensating element.
The base body of the distance compensating element is preferably made of a metal sheet, steel, stainless steel, precision foil, metal foil, light alloy, or plastics.
Furthermore, it is preferably provided that the distance compensating element comprises a hole in the bearing surface section, into which hole a fastening element can be inserted and in which the distance compensating element and the cutting insert are releasably fixed to the cutting insert receiving area. Provision is made to introduce the hole in particular in the case of a bearing surface section which covers more than 75% of the base body of the cutting insert. Alternatively, provision can be made for the bearing surface section of the distance compensating element, which covers less than 75%, preferably less than 50% of the base body of the cutting insert, to have a cutout, so that the cutting insert can be fixed in the cutting insert receiving area by means of a fastening element, in particular a screw. In this case, the distance compensating element is held clamped between the cutting insert and the cutting insert receiving area by the at least one surface section. Furthermore, it can alternatively be provided that the distance compensating element is held down in relation to the cutting insert by means of a claw, and this cutting insert is in turn secured in the cutting insert receiving area.
Furthermore, the distance compensating element can alternatively have a bearing surface section with a reduced planar extent in relation to the base body of the cutting edge, and a hole for receiving a gripping or clamping element can be provided in the bearing surface section, wherein the hole is surrounded in sections or entirely by a clamping area. This can consequently make improved fixing and clamping of the distance compensating element possible.
The at least one surface section oriented at an angle to the bearing surface section preferably has, at the free end, an enlarged end surface section which preferably has a round, oval, angular or a further freely selectable contour profile or in the case of which the surface sections have a connecting web at their end remote from the bearing section.
The object underlying the invention is furthermore solved by a distance compensating element for positioning reground cutting inserts in a cutting insert receiving area of a tool holder, in which a base body comprises one or more features of the above-described embodiments.
In particular, a base body with at least one surface section is provided, the length and/or height of which is a multiple of the thickness of the base body of the distance compensating element. The thickness of the base body is in this case preferably adapted to the removal of the material of the cutting inserts during the regrinding operation. As a result, after inserting the distance compensating element and positioning it in relation to the reground cutting insert in the cutting insert receiving area, the reground cutting insert is able to assume a position corresponding to the position of a cutting insert in the original state.
Furthermore, provision is advantageously made for the base body of the distance compensating element to have at least one surface section and one bearing surface section, wherein the at least one surface section is oriented at an angle with respect to the bearing surface section. The angular position of the surface section with respect to the bearing surface can be adapted to the angle of the side face of the cutting insert. The number and/or the size of the surface section or surface sections preferably correspond to the cutting geometry of the cutting insert, which faces the wall section or sections of the cutting insert receiving area.
The at least one surface section and the bearing surface section of the distance compensating element advantageously comprise the same thickness and are formed from a plate-shaped material. This allows such distance compensating elements to be produced simply and economically.
Furthermore, it is preferably provided that, by way of the surface sections, arranged at an angle to the bearing surface section, of the distance compensating element, a clamping fit for its self-retaining positioning or disposal on the cutting insert is formed. This allows the assembly process to be simplified. The distance compensating element can initially be placed on the cutting insert. Simple insertion into the cutting insert receiving area can be effected by way of the self-retaining positioning of the distance compensating element on the cutting insert, in order to subsequently fix the cutting insert together with the distance compensating element in the cutting insert receiving area according to the clamping and/or gripping system.
The invention and also further advantageous embodiments and developments thereof are described and elucidated in more detail below on the basis of the examples illustrated in the drawings. The features to be taken from the description and the drawings can be applied according to the invention individually per se or in any desired combination. In the drawings:
A cutting tool 11 is shown in
The tool holder 12 is configured as a clamping holder, for example. It goes without saying that further tool bodies, such as drilling bodies or milling bodies comprising one or more cutting insert receiving areas 16, can be provided instead of a clamping holder.
The cutting insert 16 has a parallelogram basic shape which comprises two cutting edges 18, 19 oriented opposite one another. This cutting insert 16 is illustrated merely by way of example. Various basic shapes, such as square, rectangular, triangular, round, hexagonal or octagonal cutting inserts, as well as further embodiments, can be provided instead of this cutting insert 16. The same is true for the cutting insert type and/or size, as well as for the insert thickness of the cutting edges. By way of example, the cutting edges of the cutting inserts can have different hardnesses and different materials, such as POD (polycrystalline diamond), CBN (cubic boron nitride), CVD (thick-film diamond), ceramic, carbide, steel, or the like. ISO indexable inserts are preferably used.
As an alternative to fixing the cutting insert 16, as shown in
The cutting insert 16 rests on a bearing surface 23 of the cutting insert receiving area 14 after it has been fastened using the gripping and/or clamping element 17 in the cutting insert receiving area 14. At least one side face 21 of the cutting insert 16 additionally abuts at least one wall section 24 of the cutting insert receiving area 14 so that the cutting insert 16 is positioned securely, in particular centrally, in the cutting insert receiving area 14. The side face 21 of the cutting insert 14 can be oriented with or without a clearance angle.
A distance compensating element 25 is provided to compensate for the removal of material when the cutting inserts 16 are reground once or multiple times. A first embodiment of the distance compensating element 25 is illustrated in
By positioning the distance compensating elements 25 between the cutting insert 16 and the wall section or sections 24 of the cutting insert receiving area 14, the removal of material is compensated for. The previous fastening can be retained as a result. At the same time, the orientation of the cutting edges remains the same in the tool holder 12 in terms of their height and plane or position with respect to the cutting insert 16, which is in its original state or brand new.
If the cutting inserts 16 are reconditioned again a second or third time by regrinding, use is made of the distance compensating elements 25 which correspond in total to the amount of material removed in the two or three regrinding operations. By way of example, standardised distance compensating elements 25 having different thicknesses can be provided. The distance compensating element 25 with the thickness I has a thickness of 0.3 mm, for example, and is used after the first regrinding operation. The distance compensating element 25 with the thickness II has a thickness of 0.6 mm, for example, and is used after the same cutting insert 16 has been reground a second time.
A distance compensating element 25 as per
The bearing surface section 33 corresponds at least in part to the bearing surface of the cutting insert receiving area 14, so that the cutting insert 16 rests with its entire base surface 31 on the bearing surface 23, with the interposition of the bearing surface section 33 of the distance compensating element 25, and can be supported.
Due to such a distance compensating element 25 as per
Depending on how the cutting insert 16 is fastened or clamped in the cutting insert receiving area 14, the bearing surface section 33 and/or the at least one surface section 28 can have corresponding perforations and/or cutouts.
The distance compensating element 25 as per
Furthermore, the distance compensating element 25 with the bearing surface section 33 and the at least one surface section 28 can be used for a cutting insert 16 in the case of which at least the side face 21 and the rake surface 29 are machined by regrinding. This is illustrated in
A right and a left surface section 28 adjoin the bearing surface section 33. It is also possible to provide two or more surface sections 28 at each side face. These surface sections 28 are arranged at an angle to the bearing surface section 33. The enclosed angle α, which is illustrated in
This annular contour of the bearing surface section 33 can encompass a three-quarter circle or else a smaller circumference. A semi-circular contour is preferably provided. The surface sections 28 have lateral edges which can likewise be arranged at an angle, so that the latter widen towards the free end of the surface sections 28.
The distance compensating element 25 is set further back than an active cutting edge by way of the shortened bearing surface section 33, thereby preventing chips from becoming jammed, in particular in the case of a finishing cut.
The alternative embodiments, as per
A reverse alignment of the longitudinal axes of the surface sections 28 can also be provided, i.e., the free end sections 34 are oriented to lie close to one another and the points of attachment of the surface sections 28 to the bearing surface section 33 are remote from one another.
Number | Date | Country | Kind |
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PCT/EP2020/056185 | Mar 2020 | EP | international |
10 2020 121 137.6 | Aug 2020 | DE | national |
10 2020 121 556.8 | Aug 2020 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/078002 | 10/6/2020 | WO |