DE202015009492U1 - Fixing screw and cutting tool - Google Patents

Abstract

A fixing screw (5) for fixing a cutting plate (4) in a groove (3) of a receiving shaft (2) of a cutting tool (1), having a head (51) and a shaft (53) having an external thread (531) therethrough in that a thickened pressure region (52) is provided between the head (51) and the shaft (53).

Description

The invention relates to a fastening screw for fastening a cutting plate in a groove of a receiving shaft of a cutting tool, according to the closer defined in the preamble of claim 1. Art. Furthermore, the invention relates to a cutting tool according to the preamble of claim. 4

The processing of free-form surfaces, as used inter alia in die and mold or the aerospace industry, is usually done by means of copy cutters, which depict a spherical or toroidal shape in a rotation about its central axis. In this case, a double-edged, exchangeable cutting plate for milling and drilling is often used, which are accommodated centrally in a receiving shaft with an end, serving for receiving the cutting plate groove with a circular passage opening through which a fastener for securing the position of the insert is screwed. These copy routers are used for roughing or finishing metallic as well as non-metallic materials.

The cutting plates of copy cutters differ in terms of the attachment of the same from those in the DIN ISO 1832 respectively. DIN ISO 6987 described inserts. While at the cutting plates after DIN ISO 1832 the attachment by means of screw or clamp on claws or bolts is done, so that here the inserts are pressed against a support on one side, cutting plates of copy cutters in a groove in a receiving shank of a cutting tool between a first and second end portion with the inclusion of a through hole of the insert and a passage opening in the end sections fixed by means of a fastening screw, so that it comes to a two-sided system.

In the EP 0 523 404 B1 , of the DE 103 08 036 B4 and the DE 600 06 839 T2 are described cutting inserts, which are provided offset by 180 ° cutting edges. By loosening the fastening screw the worn cutting edge can be changed or turned to bring another cutting part in use, which is present on this cutting plate.

However, all of the known types of fastening can lead to problems when using the cutting plate in the cutting tool, in particular as far as the exact positioning of the cutting plate within the cutting tool is concerned.

It is therefore an object of the present invention to provide a fastening screw for fastening a cutting plate in a groove of a receiving shaft of a cutting tool, which ensures a more reliable attachment of the cutting plate.

According to the invention, this object is achieved by the features mentioned in claim 1.

Due to the thickened pressure area, which can also be referred to as diameter enlargement or thickening, a defined preferred position of the cutting plate is achieved in the groove of the cutting tool.

In a very advantageous development of the invention can be provided that the pressure range is formed so that there is a point-like contact between the mounting screw and the cutting plate. This leads to a very exact positioning of the cutting plate relative to the cutting tool.

In a further advantageous embodiment of the invention, the pressure region has a continuous transition to the shaft, the diameter of the fastening screw in the contact area to the passage opening of the cutting also increases steadily during the screwing of the fastening screw and thereby increasingly presses on the bottom of the groove facing side the passage opening of the cutting plate, whereby the cutting plate is pressed against the bottom of the groove.

In claim 4, a cutting tool is specified with a fastening screw according to the invention.

The configured mounting screw according to the invention and the matching cutting tool according to the invention allow a simple and secure alignment and fixation of the cutting insert in the cutting tool and thus represent an advantageous alternative to the prior art. A readjustment of the cutting insert after the cutting insert change or insert application is dispensed with in this cutting tool , This results from the offset of the central axis of the passage opening relative to the central axis of the second bore portion of the bore, a bias voltage between the cutting plate, the fastening screw and the receiving shaft of the cutting tool.

In order to achieve a very exact contact of the cutting plate in the groove of the cutting tool, it can be provided that the fastening screw with the circular shape of the cross section of the through hole of the cutting plate forms a one-point system

If it is further provided that the cutting plate rests with a two-point system at the bottom of the groove, the result is a clear preferred position of the cutting plate.

Embodiments of the invention are described in principle with reference to the drawings.

It shows:

1 an exploded perspective view of the cutting tool according to the invention;

2 a front part of the receiving shaft of the cutting tool 1 ;

3a - 3g an overview of one-sided inserts with different arc-shaped cutting edges;

4a - 4b two inserts with 180 ° offset cutting edges for double use;

5a - 5b Detailed views of two inserts;

6 a detailed view of a cutting edge;

7 a fixing screw for fixing a cutting plate to a receiving shaft;

8th a section through the cutting tool in the receiving area of the cutting plate;

9a - 9b Cuts by cutting tools in the receiving area of the cutting plate; and

10 a pressing tool for the production of inserts.

An in 1 in its entirety and in 2 enlarged illustrated cutting tool 1 has a receiving shaft 2 on, which is designed for use in a machine tool, not shown. The intake shaft 2 has a groove 3 for receiving a cutting plate 4 as well as a hole 6 in which a fixing screw 5 for securing the position of the insert 4 on the cutting tool 1 can be screwed. In the cutting tool 1 In the present case, this is a copy milling cutter for which the cutting plate described in more detail below 4 is particularly well suited.

The front part of the receiving shaft 2 is in a first end section 21 and a second end portion 22 split, between which the groove 3 located. The groove 3 is designed to be open at the front and has two to a longitudinal axis 25 of the host 2 parallel interior side walls 31 . 32 as well as a floor 35 on.

The hole 6 extends in the front part of the receiving shaft 2 both perpendicular to the longitudinal axis 2 of the host 2 as well as perpendicular to the parallel inner side walls 31 . 32 the groove 3 , The hole 6 is doing from a first hole section 61 passing through the first end section 21 of the host 2 extends, and from a second bore portion 62 formed, extending through the second end portion 22 of the host 2 extends.

The first hole section 61 points from the peripheral region of the first end portion 21 of the host 2 a funnel-shaped reduction for guiding and securing a suitably trained head 51 the fixing screw 5 on.

The second bore section 62 has an in 8th illustrated internal thread 621 for screwing in a corresponding external thread 531 a shaft 53 the fixing screw 5 on.

For securing the position or fastening of the insert 4 in the groove 3 of the host 2 of the cutting tool 1 becomes the fixing screw 5 through the first hole section 61 the bore 6 and through a through hole 45 the corresponding in the groove 3 placed insert 4 passed and into the internal thread 621 of the second bore section 62 the bore 6 screwed. In this case, the passage opening 45 the cutting plate 4 at its edges a chamfer, which is the implementation of the fastening screw 5 through the passage opening 45 facilitated. The bevel is in this case to respective bearing surfaces 46 . 47 the cutting plate 4 made.

In the 3a - 3g are different embodiments of the cutting plate 4 shown. The 4a and 4b show two further embodiments of the cutting plate 4 , each with 180 ° offset cutting edges for use twice, wherein in 4a an insert 4 for a ball cutter and 4b an insert 4 is shown for a Torusfräser. 5a shows the double-sided insert 4 out 4a on an enlarged scale. In a similar way shows 5b the one-sided insert 4 out 3e on an enlarged scale. In 6 is a cutting edge of the insert 4 out 5a shown enlarged again. From these figures, it can be seen that the invention applies to many types of inserts 4 is applicable

All inserts 4 The above figures have at least one, in the present case two cutting edges 41 . 42 or several cutting edges 411 . 421 . 412 . 422 , several clamping surfaces 481 . 482 . 483 . 484 , several open spaces 491 . 492 . 493 . 494 , the passage opening 45 and the two opposing bearing surfaces 46 . 47 on. The cutting edge 41 . 42 or 411 . 421 or 412 . 422 is, as is well known, between the rake face 481 . 482 or 483 . 484 and the peripheral surface, which is the free surface 491 . 492 or 493 . 494 forms, arranged. It is in a comparison of the cutting plates shown in the various figures 4 to recognize that they have both simple, straight as well as complex, undercuts cutting edges 41 . 42 or 411 . 421 or 412 . 422 , may have.

The cutting plate 4 is made by pressing and sintering a cutting powder. As the cutting material powder are preferably WC-Co hard metals, WC (Ti / Ta / Nb) C-Co hard metals, TiC / TiN-Co / Ni cermets, PM-HSS, or cutting ceramic, with hard metal cutting powder are particularly preferred. After pressing and sintering, if necessary, only the bearing surfaces 46 and 47 processed material removal, in particular ground, whereas the at least one cutting edge 41 . 42 . 411 . 421 . 412 . 422 , the rake surfaces 481 . 482 . 483 . 484 and the open spaces 491 . 492 . 493 . 494 be left in the sintered state. Also the bearing surfaces 46 and 47 may optionally be left in the sintered state. By pressing and sintering without the subsequent material-removing treatment, a cutting plate 4 produced, the dimensional accuracy of the tolerance classes J, K, L, M and N after DIN ISO 1832 enough. The tolerance with regard to the diameter and the insert length is ± 0.05 mm.

Through the material-removing machining of the bearing surfaces 46 and 47 becomes a level, accurate fit of the insert 4 on the inside walls 31 . 32 the groove 3 guaranteed, if necessary. The waiver of the material-removing machining of the bearing surfaces 46 and 47 at least one cutting edge 41 . 42 . 411 . 421 . 412 . 422 , the ripping surfaces 481 . 482 . 483 . 484 and the open spaces 491 . 492 . 493 . 494 and leaving them in the sintered state is for a tailored use of the insert 4 in the cutting tool 1 completely sufficient and allows a simple, fast and cost-effective production of the cutting plate 4 ,

In the 7 enlarged illustrated fastening screw 5 points between her head 51 and her shaft 53 a diameter enlargement or a thickening or a thickened pressure area 52 on, steady to the shaft 53 passes. This pressure area 52 serves to create a preload between the insert 4 , the fixing screw 5 and the intake shaft 2 through which the cutting plate 4 in a defined preferred position in the groove 3 is pressed. Preferably, the pressure area 52 designed so that a point-like contact between the thickened pressure area 52 the fixing screw 5 and the lateral surface of the passage opening 45 the cutting plate 4 results, causing the cutting plate 4 very exactly opposite the cutting tool 1 is positioned.

To the cutting plate 4 in the defined preferred position in the groove 3 of the host 2 to bring, is the cutting plate 4 first, as in 8th represented by hand in the groove 3 inserted. This is done between the above with reference to the 5a and 5b illustrated and designated contact surfaces 43 . 44 . 431 . 432 . 441 . 442 the cutting plate 4 and the inside walls 31 . 32 the groove 3 , In order to obtain a later safe investment, are corresponding to the central axes of the through hole 45 the cutting plate 4 and the second bore portion 62 the bore 6 slightly offset from each other. In this way, a bias of the insert results 4 in the groove 3 , The fixing screw 5 can still through the first hole section 61 and the through hole 45 pushed and into the second hole section 62 be screwed, since both the diameter of the first bore section 61 the bore 6 as well as the minimum diameter of the through hole 45 the cutting plate 4 at least the maximum diameter of the contact area 52 the fixing screw 5 and thus are larger than the diameter of the shaft 53 the fixing screw 5 ,

Will now the shaft 53 the fixing screw 5 through the passage opening 45 the cutting plate 4 in the second bore section 62 the bore 6 screwed in, so the pressure area 52 the fixing screw 5 in the direction of R1 on the passage opening 45 the cutting plate 4 drawn. Because of the pressure area 52 a steady transition to the shaft 53 the fixing screw 5 has, the diameter of the fastening screw grows 5 in the contact area to the passage opening 45 the cutting plate 4 in the course of screwing the fastening screw 5 also steadily and therefore increasingly presses on the ground 35 the groove 3 facing side of the passage opening 45 the cutting plate 4 , whereby the cutting plate 4 in the direction of R2 against the ground 35 the groove 3 is pressed. This will make the insert 4 subjected to a bias voltage.

In addition, a further bias of the insert 4 against the groove 3 of the cutting unit train 1 This causes the fixing screw 5 is designed as a countersunk screw, ie that the head 51 has a conical shape, and, as already described above, the first bore portion 61 the bore 6 in the first end section 21 of the host 2 matching a funnel-shaped depression, wherein the axis of the bore 6 opposite the axis of the passage opening 45 the cutting plate 4 in the direction of the ground 35 the groove 3 is offset. Now the fixing screw 5 screwed in, so presses her Andruckbereich 52 additionally reinforced towards R2 to the ground 35 the groove 3 and increasingly on the inner wall of the through hole 45 and thus clamps the cutting plate 4 against the groove 3 in front.

When tightening the fixing screw further 5 become the inside walls 31 . 32 the groove 3 pulled against each other and cover the side walls 46 . 47 the cutting plate 4 positive and frictional, whereby the clamping of the cutting plate 4 and thus their alignment and fixation or indexing in the cutting tool 1 is further improved.

In 9a is a reversible insert 4 or an indexable insert 4 and in 9b a one-sided insert 4 shown. In particular from the 9a and 9b shows that the passage opening 45 the cutting plate 4 has a circular cross-section. This circular cross-section of the passage opening 45 is also left after sintering and not processed. The circular cross section allows one in the 9a and 9b clarified one-point system A3 of the fixing screw 5 at the passage opening 45 , by the diameter enlargement or the thickening or the thickened pressure area 52 is reached. The pressure area 52 the fixing screw 5 forms when tightening the mounting screw 5 in the internal thread 621 of the second bore section 62 the bore 6 with the circular cross section of the passage opening 45 the cutting plate 4 on the inner wall in the 9a and 9b clarified one-point system A3, which also causes a bias of the insert 4 against the groove 3 of the cutting tool 1 results. Furthermore, in both embodiments of the cutting plate 4 of the 9a and 9b a two-point system A1, A2 of the cutting plate 4 on the ground 35 reached the groove. By a correspondingly executed fixing prism lies the insert 4 while in a clear preferred position. The points A1, A2 of the two-point system A1, A2 and the point A3 of the one-point system A3 form a triangle of forces, which among other things, for a secure hold of the insert 4 in the groove 3 of the host 2 of the cutting tool 1 contributes.

By rotation of the cutting tool 1 around its longitudinal axis 25 , in the escape of which the cutting plate 4 at the front end of the receiving shaft 2 between the two end sections 21 and 22 located, and by engaging the cutting plate 4 With a workpiece, not shown, a removal of the material to be machined is achieved. The cutting edges penetrate 41 . 42 with one-sided inserts 4 or the cutting edges 411 . 421 or 412 . 422 in indexable inserts by the design as a bow or helix gradually into the material. Due to this gentle penetration, the load on the cutting edges 41 . 42 or 411 . 421 or 412 . 422 continuously increased and guarantees maximum stability. In contrast, jerky entry into the material, as is the case with the prior art, results in an abrupt loading which can lead to premature failure of the insert in the form of chipping and, in the worst case, cutting plate fracture ,

For the production of the cutting plate 4 , which has already been briefly mentioned above, pressing and sintering is used. This is an in 10 illustrated pressing tool 7 used, which is an upper punch 71 , a lower stamp 72 and two movable die elements 73 and 74 having. Another component of the pressing tool 7 is a thorn 75 , which for generating the through hole 45 the cutting plate 4 is used. In the process, the geometry of the rake faces becomes 481 . 482 . 483 . 484 the cutting plate 4 already during the production of the pressing tool 7 both in the upper stamp 71 as well as in the lower stamp 72 integrated. The geometry of the peripheral surfaces, ie open spaces 491 . 492 . 493 . 494 is doing in the matrices 73 . 74 integrated.

For the production of the cutting plate 4 First, the cutting material powder in the closed molds serving as a negative mold 73 . 74 filled. Here, an unillustrated filling shoe is used, which over the respective die 73 . 74 slides and receives the supply of cutting material from a storage container. After the filling process, the pressing process begins by moving the upper punch 71 , the lower stamp 72 and the thorn 75 , The ejection process of the compact is done firstly by moving the upper punch 71 , the lower stamp 72 and the thorn 75 against the pressing direction and on the other hand by movement of the die elements 71 . 72 in the longitudinal direction L1 and L2. After pressing, the sintering takes place, giving the compact its final strength and then, as mentioned above, only the bearing surfaces 46 . 47 if required, undergo a material-removing machining.

In the process, both the rake surfaces receive 41 . 42 or 411 . 421 or 412 . 422 as well as the open spaces 491 . 492 or 493 . 494 their geometric final design already in the design of the pressing tool 7 , Characterized in that the geometric final shape with the exception of the already mentioned above, the pressing and sintering subsequent material-removing machining of the support surfaces 46 . 47 with the pressing tool 7 is achieved, no material-removing machining in the form of loops is required, so that damage to the cutting edge 41 . 42 or 411 . 421 or 412 . 422 is eliminated. Likewise, the risk of cobalt leaching is reduced to a reasonable minimum.

In order to compensate for a shrinkage of the pressed blank occurring during sintering, it is preferably initially determined empirically, ie by repeatedly producing and measuring differently dimensioned cutting blank blanks in an iterative process, as the shape of the sintered blank changes with respect to the shape of the pressed blank. Thereafter, the pressing train 7 adjusted so that the sintered blank except the material-removing machining on the bearing surfaces 46 . 47 the cutting plate 4 no longer undergoes any processing to get its final shape.

As another manufacturing method for improving the properties of the cutting edge 41 . 42 or 411 . 421 or 412 . 422 a beam processing can be used. This is the cutting edge 41 . 42 or 411 . 421 or 412 . 422 irradiated by means of alumina with a particle size of 8 microns-27 microns at a pressure of 1.5-5.0 bar. As a result of this irradiation, the susceptibility to optimum layer adhesion with respect to the downstream coating process is considerably improved, since the present sintered skin is made correspondingly wettable. Following this blast treatment, the coating of the cutting plate takes place 4 using PVD or CVD methods.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0523404 B1 [0004]
• DE 10308036 B4 [0004]
• DE 60006839 T2 [0004]

Cited non-patent literature

• DIN ISO 1832 [0003]
• DIN ISO 6987 [0003]
• DIN ISO 1832 [0003]
• DIN ISO 1832 [0035]

Claims (6)

Fixing screw ( 5 ) for fastening a cutting plate ( 4 ) in a groove ( 3 ) of a host ( 2 ) of a cutting tool ( 1 ), with a head ( 51 ) and a shaft ( 53 ), which has an external thread ( 531 ), characterized in that between the head ( 51 ) and the shaft ( 53 ) a thickened pressure area ( 52 ) is provided. Fixing screw ( 5 ) according to claim 1, characterized in that the pressure area ( 52 ) is formed so that a point-like contact between the fastening screw ( 5 ) and the cutting plate ( 4 ). Fixing screw ( 5 ) according to claim 1, characterized in that the pressure area ( 52 ) a steady transition to the shaft ( 53 ) having. Cutting tool ( 1 ) with a receiving shaft ( 2 ) inserted in a first end section ( 21 ) and a second end portion ( 22 ) split end, between which a groove ( 3 ) with parallel inner side walls ( 31 . 32 ) for receiving a cutting plate ( 4 ) is formed, and with a fastening screw ( 5 ), which has a head ( 51 ) and a shaft ( 53 ) with an external thread ( 531 ) and to secure the position of the insert ( 4 ) in a direction perpendicular to a longitudinal axis ( 25 ) of the host ( 2 ) and perpendicular to the parallel inner side walls ( 31 . 32 ) of the groove ( 3 ) running bore ( 6 ) is screwed in such a way that the fastening screw ( 5 ) in the screwed state through a passage opening ( 45 ) in the cutting plate ( 4 ), wherein the bore ( 6 ) a first, through the first end portion ( 21 ) of the host ( 2 ) extending bore section ( 61 ) and a second, through the second end portion ( 22 ) of the host ( 2 ) extending bore section ( 62 ), wherein the second bore section ( 62 ) to the external thread ( 531 ) of the shaft ( 53 ) corresponding internal thread ( 621 ), and wherein the central axes of the passage opening ( 45 ) and the second bore section ( 62 ) of the bore ( 6 ) are offset from each other, characterized in that the fastening screw ( 5 ) according to one of claims 1 to 3 is formed. Cutting tool ( 1 ) according to claim 4, characterized in that the fastening screw ( 5 ) with the circular shape of the cross section of the passage opening ( 45 ) of the cutting plate ( 4 ) forms a one-point system (A3). Cutting tool ( 1 ) according to claim 4 or 5, characterized in that the cutting plate ( 4 ) with a two-point system (A1, A2) on the ground ( 35 ) of the groove ( 3 ) is present.

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