Technical Field of the Invention The present invention relates to a device for parallel displacement of insert holders included in a set of insert holders for metal cutting, especially parting or grooving.

Prior Art In connection with insert holders adapted for inserts that perform parting or grooving it is common that a set of insert holders are arranged side by side, adjacent inserts being clamped in said respective holders and having equidistant relationship relative to each other. Spacers are used to achieve said equidistant relationship, said spacers being applied between the insert holders. This technique will be described more in detail with reference to Figure 1. Since this handling of spacers is performed manually it is at once realised that such arrangement is time consuming when the distance between adjacent inserts is to be changed, said equidistant relationship however being maintained. This happens quite frequently, e.g. when manufacturing parts for ball bearings. It is also difficult to manage to get said distances exactly the same since the thickness of the spacers may vary. Normally the rearrangement of the spacers is carried out by trial and error until the equidistant relationship, of required tolerance, between adjacent spacers is achieved.

Objects and Features of the Invention An object of the present invention is to present a device of the type defined above where the distance between adjacent inserts is equally large and at a high tolerance level. When the distance between adjacent inserts is to be changed only an extremely simple adjustment is required since the distance between adjacent inserts permanently is maintained the same. The object of the present invention is realised by means of a device that has been given the characteristics of the appending claims.

Brief Description of the Drawings Below the principles of prior art and an embodiment of the device according to the invention will be described, reference being made to the accompanying drawings, where Figure 1 schematically shows the principles of prior art; Figure 2a-2b show in top view a set of tools equipped with a device according to the present invention in two different setting positions; Figure 2c shows in side view the set of tools according to Figure 2a-2b; Figure 3 shows in an enlarged scale a top view of the device according to the invention at the setting position according to Figure 2b.

Detailed Description of Prior Art and an Embodiment of the Present Invention The device according to prior art shown in Figure 1 includes a number of insert holders A that each receives an insert B for parting or grooving. As is evident from Figure 1 the insert holders A are clamped in a recess C of a shank D, a screw E urging the set of holders towards one limiting surface of the recess C. Spacers F are provided between adjacent insert holders A, said spacers F having the same extension in the axial direction of the screw E. When the internal, equally large, distance between adjacent insert holders A is to be changed the screw E must be loosened and the spacers rearranged by trial and error until the new, equally large, distance between adjacent inserts is created.

In such a case several spacers F may be positioned between two adjacent insert holders A, this further complicating the operation and makes it more difficult to achieve equally large distances between adjacent inserts.

The set of tools shown in Figure 2a-2c includes a number of insert holders 10a-10e that are arranged side by side at an internal equidistant relationship between adjacent insert holders. Each insert holder 10a-10e receives an insert, in the disclosed embodiment a

parting or grooving insert 12. It is at once realised from Figures 2a and 2b that the distance between adjacent inserts 12 is larger in Figure 2b than in Figure 2a, said parallel displacement of the insert holders 10b10e has been effected by means of a device according to the invention that will be described more in detail below, reference being made to Figure 3.

From Figure 2a-2c it is also evident that the insert holders lOa-lOe are secured in an adapter 14 via a kind of dovetail coupling 16, see Figure 2c. The dovetail coupling 16 fixes the insert holder 1 0a in all directions except that it allows the insert holders lOb- 10e to be displaced in the plane of the paper in Figure 2a and 2b. In every other direction the coupling 16 fixes the insert holders 10b-10e. The displacement of the insert holders 10b-10e in the plane of the paper in Figures 2a and 2b is taken care of by the device according to the present invention. However, it should be pointed out that the insert holders 10b-10e are displaceable in the plane of the paper of Figure 2a and 2b only when the device according to the invention is activated.

The device according to the invention, disclosed more in detail in Figure 3, includes a system of threaded screws that are described in detail below as well as the function of the device. In Figure 3 centre lines of the inserts 12 have been introduced in order to define the distances between adjacent inserts 12 that according to the invention may be varied, however said distances should always be equally relative to each other. The distances in question is designated by W in Figure 3.

As pointed out above the first insert holder 10a is completely fixed, i.e. stationary, relative to the adapter 14 via the dovetail coupling 16. The first insert holder 10a has a through-going opening 18, a first, externally right hand threaded, screw 20 passing through said opening 18 without cooperating with the first insert holder 1 0a. The right hand thread 21 of the first screw 20 has a pitch S. At the left end in Figure 3 of the dovetail coupling 16 a support 22 is provided, said first screw 20 being non-rotatably fixed in said support 22.

The second insert holder 1 orb is provided with a first nut 24 having an internal right hand thread 25, said nut 24 being rotatably received in the second insert holder lOb.

However, said first nut 24 is fixed axially relative to the second insert holder lOb. In the first nut 24 a second, externally and internally right hand threaded, screw 26 is received, the external right hand thread 28 of the second screw 26 cooperating with the internal right hand thread 25 of the first nut 24. The external right hand thread 28 of the second screw 26 and the internal right hand thread 25 of the first nut 24 has a pitch of 0,5S, this being half of the pitch S of the external right hand thread 21 of the first screw 20.

The internal right hand thread 27 of the second screw 26 cooperates with the external right hand thread 21 of the first screw 20, the internal right hand thread 27 of the second screw 26 thus also having the pitch S. As is evident from the sectioned portion of Figure 3 the internal right hand thread 27 of the second screw 26 has such an axial extension into the second screw 26 that the first screw 20 may be threaded into the second screw 26 so far that the position according to Figure 2a is realised.

The third insert holder 1 Oc is attached to the second screw 26 in such a way that the third insert holder l Oc is fixed in axial direction of the second screw 26 but said third insert holder lOc and said second screw 26 being rotatable relative to each other, i.e.

when the second screw 26 is rotated no displacement of the third insert holder 1 Oc, in the longitudinal direction of the second screw 26, occurs.

The fourth insert holder lOd is, via an internal left hand thread 30 of a second nut 32, received upon a first external left hand thread 34 of the second screw 26. The second nut 32 is rotatably received in the insert holder lOd but axially fixed relative to said insert holder lOd. The internal left hand thread 30 of the second nut 32 and the external left hand thread 34 of the second screw 26, said threads cooperating with each other, have both the pitch 0,5S. Preferably, the external right hand thread 28 of the second screw 26 and the first external left hand thread 34 have the same external diameter.

The fifth insert holder 1 owe is via an internal left hand thread 36 of a third nut 38 received upon a second external left hand thread 40 of the second screw 26, said second external left hand thread 40 having smaller external diameter than the first external left hand thread 34 of the second screw 26. This is necessary in order to mount the insert holders lOc and lOd. The internal left hand thread 36 of the third nut 38 and the second external left hand thread 40 of the second screw 26 have the pitch S, said threads cooperating with each other.

In Figure 2a, 2b and 3 a handle 42 is provided at the right end of the second screw 26, said handle 42 effecting rotation of said second screw 26.

The device described above functions in the following way. For reasons of simplicity it is assumed that the handle 42 is rotated one revolution in the direction that makes all the insert holders le alOe to be displaced to the left in Figure 3. When the handle 42 is rotated one revolution in the stipulated direction the second screw 26 will rotate one revolution. The first insert holder 1Oa will not at all be affected since the second screw 26 does not cooperate with said insert holder 1Oa.

Upon rotation of the second screw 26, relative to the first screw 20 that is non-rotatable, a displacement to the left in Figure 3 of the second screw 26 will occur due to cooperation between the internal right hand thread 27 of the second screw 26 and the external right hand thread 21 of the first screw 20, said displacement being equal to 1,OS since the right hand threads 21 and 27 have the pitch S and it is assumed that the handle 42 is turned one revolution. Simultaneously the external right hand thread 28 of the second screw 26 will rotate relative to the internal right hand thread 25 of the first nut 24. Thereby, the first nut 24 will be displaced 0,5S to the right in Figure 3 since the threads 25 and 28 have the pitch 0,5S and the second screw 26 has been rotated one revolution. The resulting displacement ofthe second insert holder lOb is thus 0,5S to the left in Figure 3 since said second insert holder lOb, via the first nut 24, is mounted upon the external right hand thread 28 of the second screw 26.

The third insert holder lOc is displaced equally far to the left as the second screw 26, i.e.

the distance 1,OS, since the third insert holder l Oc is not axially displaceable relative to the second screw 26.

The fourth insert holder 1 Od is on one hand displaced the distance 1,OS to the left in Figure 3 since the second screw 26 has been displaced the distance 1,OS to the left and the fourth insert holder is attached to the second screw 26. However, the fourth insert holder 1 Od is displaced a further distance to the left in Figure 3 since the first external left hand thread 34 of the second screw 26 cooperates with the internal left hand thread 30 of the second nut 32. Since the threads 30 and 34 have the pitch 0,5S a further displacement to the left, a distance 0,5S, of the fourth insert holder lOd occurs, thus the resulting displacement to the left in Figure 3 of the insert holder lOd being 1,5S.

The fifth insert holder 1 owe is on one hand displaced the distance 1,OS to the left in Figure 3 since the fifth insert holder lOe is attached to the second screw 26 that is displaced the distance 1,OS to the left in Figure 3. However, the fifth insert holder is displaced a further distance to the left in Figure 3 since the second external left hand thread 40 of the second screw 26 cooperates with the internal left hand thread 36 of the third nut 38. Since these threads have the pitch S a further displacement a distance 1,OS to the left of the fifth insert holder 1 Oe will occur when the second screw 26 is rotated one revolution. The resulting displacement to the of the insert holder 1 owe is thus 2,OS.

In conclusion the first insert holder 1 Oa has not been displaced, the second insert holder lOb has been displaced the distance 0,5S to the left in Figure 3, the third insert holder lOchas been dispalced the distance 1,OS to the left in Figure 3, the fourth insert holder lOd has been displaced the distance 1,5S to the left in Figure 3 and the fifth insert holder 1 Oe has been displaced the distance 2,OS to the left in Figure 3. It is thus realised that by rotation of the second screw 26, via the handle 42, the distance between adjacent insert holders has decreased the distance 0,5S in a simultaneous parallel displacement.

The provision of the internal threads 25, 34, 36 of the insert holders lOb, 10d, 1 owe in nuts 24, 32, 38 is due to the fact that by such an arrangement a calibration of the relative positions of the insert holders upon the second screw 26 is made possible. Preferably the nuts 24, 32, 38 are provided with a key means or the like in order to make it possible to easily rotate the nuts 24, 32, 38.

Feasible Modifications of the Invention Within the scope of the invention it is feasible to modify the embodiment according to Figures 2a-2c and 3 in such a way that the internal thread 27 of the second screw 26 is deleted, i.e. the first screw 20 is permanently fixed to the second screw 26. In such an embodiment the first screw 20 and the second screw 26 may be in one integral piece. In such a case the support 22 must have an internal thread that cooperates with the external thread 21 of the first screw 20, said thread coupling having a pitch S. Thus, Figure 3 shows the maximum distance between adjacent insert holders lOa-1Oe. When the distance between adjacent insert holders lOa-lOe decreases compared to the position according to Figure 3 the free end of the first screw 20 will project to the left in Figure 3 beyond the support 22.