INSERT HOLDER AND KEY FOR INSERT HOLDERS

Abstract: An insert holder (1) having a slot (2) adapted to receive a cutting insert, said slot being limited by a clamping arm (4). In the insert holder two laterally opening seats (6, 7) are provided for receiving two spaced-apart projections (13', 14') of a key (12) that is intended to bend the clamping arm (4) outwards during widening of the slot in connection with the mounting and/or dismounting of a cutting insert. One of the seats (6) has a cylindrical shape while the other seat (7) has an oblong shape in order to effect bending outwards of the clamping arm (4) by displacement of a projection (14') of the key from a point located at a certain distance from the first seat (6) to another point located at a shorter distance from said seat (6).

Description: INSERT HOLDER AND KEY FOR INSERT HOLDERS Technical Field of the Invention In a first aspect this invention relates to an insert holder of the type comprising a disc-shaped body having a slot adapted to receive a cutting insert, said slot being defined by an elastically flexible arm arranged to resiliently clamp the cutting insert in the slot, two seats, which open laterally, being provided in said insert holder in order to receive two spaced-apart projections of a key, said projections having the function of bending the clamping arm outwards and widening the slot in connection with the mounting or dismounting of the cutting insert, more precisely by turning the key around a fulcrum defined by one of the seats and a projection of the key engag- ing said seat at the same time as the other projection engages the other seat . In a second aspect the invention also relates to a key for such insert holders . Prior Art Insert holders and keys of the type generally defined above are previously known in two different embodiments in EP 0 654 316. Thus, in figures 1-4 of said document an insert holder is shown having one of its seats recessed in the flexible clamping arm while the other seat is recessed in the body itself, more precisely in a point below the slot intended for the cutting insert. In order to widen the slot of this insert holder two types of keys are suggested, the first one being shown in figure 3 and having the shape of a plate with two separated legs upon which projections in the shape of studs are provided, and between said projections there is a wedge body that by the aid of a screw mechanism may increase or decrease the distance between the legs and consequently the distance between said studs. In figure 4 an alternative of the key is shown where one projection is constituted by a rotatable eccentric body that, when turned, is able to increase the distance between the seats of the insert holder in order to bend the clamping arm outwards. However, both of these keys are structurally relatively complicated and hence expensive to manufacture. The presence of a screw mechanism also constitutes a latent risk for functional incompetence, e.g. by damaging or fouling of the threads of the mechanism. A structurally more simple and hence cheaper key is described in connection with figures 6-8 of the document. In this case two cylindrical studs are fixed upon an elongated shaft, more precisely side by side in absolute vicinity of the free end of the shaft. In connection with this key the maximum distance between the studs is determined by the width of the key shaft, said distance being relatively short and thus no stud receiving seat may be provided in the body itself in the area below the slot intended for the insert. Accordingly, one of these two studs must be applied against an abutment or in a seat in the absolute vicinity of the clamping arm. A disadvan- tage of this key, which in itself is simple and cheap, is, however, that it requires continuous power supply in order to maintain the arm bent outwards . In other words the clamping arm returns to its starting position as soon as the key is released. Another disadvantage is that a large manual force is required to bend the clamping arm outwards since the distance between the studs is small. A serious disadvantage is also that the bending outwards of the clamping arm takes place in an uncontrolled way. If the operator applies an excessive force upon the clamping arm, said arm may be plastically deformed and thus unusable . Objects and Features of the Invention The present invention aims at overcoming the disadvantages mentioned above in connection with prior art and to cre- ate an improved combination of insert holder and key. Thus, a primary object of the invention is to create an insert holder and a key in combination with each other guarantee a predictable deflection or bending of the clamping arm while using a reasonable manual force simultaneously as the key should be structurally simple and cheap to manufacture. A further object is to create an insert holder and a key which makes it possible to automatically maintain the key in a condition where the clamping arm is kept deflected, i.e. without applying a manual force to the key. According to the invention at least the primary object is achieved by means of the features being defined in the characterising portions of claims 1 and 5. Preferred embodiments of the invention are defined in the dependent claims. Brief Description of the Appended Drawings In the drawings : Figure 1 is a partial perspective view of a key according to the invention, Figure 2 is a side view of an alternative embodiment of the key according to the invention, Figure 3 is an analogous side view turned 90°, Figure 4 is a partial side view showing an insert holder of blade type and the adherent cutting insert, Figure 5 is a side view corresponding to figure 4, said side view showing the same insert holder without cutting insert but with an applied key, and Figure 6-8 are similar side views showing three further alter- native embodiments of the insert holder according to the invention. Detailed Description of Preferred Embodiments of the Invention Reference is first made to figures 4 and 5 illustrating an insert holder having the shape of or comprising a discshaped body 1, an outwardly opening slot or recess 2 being provided in said body 1, said slot or recess 2 being adapted to receive a cutting insert 3. The slot 2 is defined by, on one hand, a lower and forward portion of the body 1, and on the other hand, by an elastically flexible arm 4 having the function of clamping the cutting insert 3 in the slot 2. At the inner end of the slot 2 there is an abutment surface 5 against which the cutting insert abuts when mounted. In the insert holder two different seats 6, 7 are pro- vided, which may either be designed as through holes or as recesses having a limited depth and opening only at one side of the body. One of the seats 6 is cylindrical and in the disclosed embodiment located in the clamping arm 4. The other seat 7 is located in the area below the slot 5, said other seat 7, in accordance with the present invention, having an oblong shape. In the embodiment according to figures 4 and 5 the seat 7 is arched in shape and extends between opposite ends designated by 8, 8', which are located at different distances from the seat 6. More specifically, the seat or the notch is limited by a lower arc-shaped surface 9 that at the end 8' is converted into a shallow recess 10. The notch 7 is located in such a way that the radial distance from the bottom of said recess 10 is somewhat smaller than the radial distance between the seat 6 and the bottom surface 9 at the end 8. The difference in distance or radius, indicated by the designation S in figure 4, may in practice constitute fractions of a millimetre. For instance, the difference in distance S may be within the interval 0,2 - 1,0 mm, preferably 0,3 - 0,7 mm. Reference is now made to figures 1-3 illustrating two alternative embodiments of a lever key according to the invention. Generally, said key comprises a handle member 11 and a shaft 12 having at least a pair of axially spaced projections 13, 14. The only difference between the embodiment according to figure 1 and the embodiment according to figures 2 and 3 is that the shaft, in the first case, has a rectangular cross-section, i.e. the shaft is flat, while the shaft according to figures 2 and 3 is cylindrical. The first projection 13 on the shaft 12 has the shape of a cylindrical stud whose diameter is only a little smaller than the diameter of the cylindrical seat 6. This means that the stud 13 projects at a right angle from the shaft 12. However, in this case the cross-section of the stud may be oval or elliptic, more precisely in such a way that the major axis of the ellipse is oriented perpendicular to the longitudinal axis of the shaft. By this oval or elliptic shape of the stud surface contact rather than line contact is established against the bottom surface 9 when the stud is applied in the notch 7 ; what facilitates the displacement of the stud along the bottom surface 9. The distance between the two studs 13 and 14 should on one hand be larger than 1/10 of the entire length of the shaft and on the other hand smaller than 1/3 of the entire length of the shaft. Per se both the length of the shaft as well as the distance between the studs may vary depending on which type of insert holder that is to be treated. However, the length of the shaft should be in the range of 100-200 mm and the distance between the studs may be within the range of 20-60 mm. In accordance with a preferred embodiment of the invention opposite pairs of projections are provided on the shaft 12. At the side of the shaft that is opposite to the cylindrical stud 13 there is an oval stud 14 ' and in an analogous way there is a cylindrical stud 13 ' at the side of the shaf that is opposite to the oval stud 14. In figure 5 is shown how the key is attached to the insert holder 1, more precisely with the cylindrical stud 13' mounted in the cylindrical seat 6 and the oval stud 14 ' engaging the arc-shaped notch 7. Thus, in this case the key is oriented downwards from the insert holder. If the operator wishes to direct the key upwards from the insert holder, said key may be oriented in such a way that the stud 13 at the opposite side of the shaft engages the cylindrical seat 6 and the oval stud 14 engages the notch 7. From the starting position shown in figure 5 the key shaft is brought to turn counterclockwise around the fulcrum defined by the seat 6 and the stud 13'. Hereby the projection 14' is moved from one end 8 of the notch 7 to the opposite end 8 ' , whereby the stud glides along the bottom surface 9. Due to the fact that the notch is so oriented relative to the seat 6 that the radial distance to the seat 6 is shortened successively in direction towards the end 8 ' , the elastically flexible clamping arm 4 will successively bend outwards far enough to allow the insert 3 to be removed from the slot 2. When the stud 14 ' reaches the end position at the end 8' of the notch it will be positioned in the recess 10, this arrangement guaranteeing that the key is automatically maintained in its inner end position. In other words the operator does not need to apply any force upon the key to keep the clamping arm 4 bent outwards. Therefore, it is not necessary to actuate the key until a new (or indexed) insert is introduced into the slot and the clamping arm again is to be actuated. It should be pointed out that the radial distance between the seat 6 and the recess 10 is somewhat larger than the corresponding distance from the bottom surface 7 in the absolute vicinity of the recess. Nevertheless the radial distance between the recess and the seat 6 is obviously smaller than the corresponding radial distance at the opposite end 8 of the notch. In figure 6 an alternative embodiment of the insert holder is shown, the oblong seat or notch 7 in its bottom surface having a central bowl-like shoulder surface 10' located at a radial distance from the seat 6, said distance being at least somewhat smaller than the corresponding radial distance at the opposite ends of the notch. In this case the key may thus be turned inwards from either one of the two opposite ends of the notch and effect bending outwards of the clamping arm when the stud reaches the shoulder surface 10 ' . In figures 7 and 8 are shown examples of straight notches, the notch according to figure 7 including a recess at one end thereof, while the notch according to figure 8 is void of a special, position-maintaining recess. In practice the geometric shape of the oblong seat may be varied in many ways. Thus, essential for the invention is only that said seat generally has an oblong shape and that the radial distance between on one hand the fulcrum defined by a cylindrical seat and a first projection and on the other hand the surface of the seat abutting the second projection is shortened when the second projection is displaced along a running surface of the seat. Although it is preferred to locate the fulcrum seat in the clamping arm and the oblong seat in the body of the insert holder, as is shown in the drawings, it is per se feasible to arrange this in a reversed way, i.e. locate the oblong seat in the clamping arm and the fulcrum seat in the body.

Claims: Claims 1. Insert holder comprising a disc-shaped body (1) having a slot (2) adapted to receive a cutting insert (3), said slot (2) being defined by an elastically flexible arm (4) arranged to resiliently clamp the cutting insert in the slot, two seats (6, 7), which open laterally, being provided in said insert holder in order to receive two spaced-apart projections (13, 14; 13', 14') of a key, said projections having the function of bending the clamping arm outwards and widening the slot in connection with the mounting or dismounting of the cutting insert, more precisely by turning the key around a fulcrum defined by one of the seats (6) and a projection (13; 13') of the key engaging said seat (6) at the same time as the other projection (14, 14') engages the other seat (7), c h a r a c t e r i z e d in that said other seat (7) has an oblong shape in order to effect bending outwards of the clamping arm (4) by displacing the other projection (14, 14') of the key from a point located at a certain distance from the first seat (6) to another point located at a shorter distance from said first seat (6) . 2. Insert holder according to claim 1, c h a r a c t e r i - z e d in that the oblong seat (7) has a recess (10) at a point located at a shortened distance from the first seat (6) , said other projection (14, 14') being maintained in said recess (10) when the shaft (12) of the key is turned to an active position where the clamping arm is bent outwards. 3. Insert holder according to claim 1 or 2 , c h a r a c t e r i z e d in that the oblong seat (7) is recessed in the body (1) , while the fulcrum-defining seat (6) is recessed in the clamping arm (4) . 4. Insert holder according to any of the preceding claims, c h a r a c t e r i z e d in that the oblong seat (7) has its two opposite ends located at different distances from the seat serving as a fulcrum. 5. Key for insert holders of the kind including a disc-shaped body (1) having a slot (2) adapted to receive a cutting insert (3) , said slot (2) being limited by an elastically flexible arm (4) arranged to resiliently clamp the insert in the slot, said key comprising a shaft (12) having two spaced-apart projections (13, 14; 13', 14') each adapted to engage a seat (6, 7) which opens laterally in the insert holder in order to effect, by turning of the shaft, deflection of the clamping arm so as to widen the slot in connection with the mounting and/or dismoun- ting of a cutting insert, c h a r a c t e r i z e d in that the two projections (13, 14; 13', 14') are axially spaced- apart, more precisely by a first projection being located close to a free end of the shaft and the second projection being axially spaced from said first projection, and that the dis- tance between the projections being larger than 1/10 and smaller than 1/3 of the entire length of the shaft, one projection (13, 13') being intended to be applied in a cylindrical seat (6) in order to define a fulcrum for turning the shaft, while the other projection (14, 14') is intended to be applied in an oblong seat (7) in order to be displaced between different points when the key shaft is turned, said points being located at different distances from the fulcrum. 6. Key according to claim 5, c h a r a c t e r i z e d in that the projection (13, 13') adapted to engage the fulcrum-defining seat (6) is constituted by a cylindrical stud, while the other projection is constituted by a stud having oval cross-section. 7. Key according to claim 6, c h a r a c t e r i z e d in that opposite pairs of projections are provided on the shaft, namely, located at one side, a pair in the shape of a cylindrical stud (13') closest to the free end of the shaft and an oval stud (14') at a distance from said cylindrical stud (13'), and, located at the other side, a pair in the shape of an oval stud (14) closest to the free end of the shaft and a cylindrical stud (13) at a distance from said oval stud (14) .

Inventors: BRASK KARL-GOERAN, HANSSON PER, BRASK, KARL-GOERAN, HANSSON, PER
Applicants: BRASK KARL GOERAN, HANSSON PER, SANDVIK AB, BRASK, KARL-GOERAN, HANSSON, PER
Application year: 1998
Main classification: B23B27
IPC codes: B23B27