DE4228558C1 - Clamping device for tool holders - Google Patents

Abstract

A clamping device for coupling base holders or machine spindles to cutting tools or tool holders has two expanding spanners (22, 24) which grip from behind with radially outwards projecting clamping claws (32, 40) clamping shoulders (20, 22) arranged inside the machine spindle and tool holder (12). Two spanners (22, 24) are mutually linked in their central area by means of an expanding member (26), forming a clamping block. In the contracted state, the clamping block has an outer diameter which is smaller than the smallest inner diameter both of the machine spindle and of the tool holder.

Description

The invention relates to a clamping device for connecting Grundhal ters or machine spindles with tool holders or tools for the machining, with expandable, clamp-shaped clamping pieces, the clamping claw protruding radially outward rear inside the machine spindle and the tool holder fen.

Such a tensioning device is known from DE 39 04 259 C2. The be Known device has three clamping distributed around the circumference at 120 ° pieces on, with the claws at one end constantly in one gripped ste with an inwardly projecting shoulder of a basic holder hen. There are radial adjusting screws in the claws on the side of the tool holder ben embedded, which through a corresponding radial hole from the Au the outside of the tool holder can be actuated. The set screws point a cone-shaped tip, which with the conical tips of the other two setscrews meet. The tips pressed against each other when the adjusting screws are actuated len the clamp-shaped clamping pieces around that on the side of the basic holder Swing the lying end outwards and the claws on the side of the Tool holder engages with its inwardly projecting shoulder bring.

Compared to the suitability of this solution for practice, ver concerns for various reasons. The cone tips should have a high ver to be exposed to wear. Another disadvantage is that the work tool holder in the area of its cone with a hole must, so that it is not possible to use any tool holder. How a look at the drawing shows a very large number of parts required derlich, so that both the manufacture and assembly as well as the maintenance are agile. There is only axial permeability for coolant lines with restrictions.

Ejecting the tool holder, its mostly flat conical Shank in the machine spindle or in the basic holder with self-locking is clamped is not possible when loosening the tool holder.  

In particular with the tool holders specified in DIN 69893 or Tools with hollow shanks, the need arises next to already known mechanisms for automatic clamping with machines spindles to create such jigs that operate manually can be done. Doing so ensures a safe function and to limit the construction effort various demands fulfill:

• - The clamping force should be as uniform as possible on several on the circumference distributed tension points of the inwardly projecting shoulder or Clamping surface of the hollow shaft of the tool holder can be distributed. Just this ensures that the Ef effect of an elastic deformation of the relatively thin-walled cone to achieve high pressure on the In cone of the machine spindle or the base holder is reached. Egg ne even axial tensile force results in a firm chip between the end face of the machine spindle or the base ters and the flange of the tool holder. Since the ideal case of a fully support of the clamping device on the entire circumferential Shoulder is practically unreachable, at least one should ß distribution over several defined clamping surfaces can be achieved.
• - The resulting lines of force should be as short as possible, and the on the machine spindle or the basic holder on the one hand and the movement Tool holders, on the other hand, exerted transverse forces should be as low as possible his.
• - There should be the possibility. Coolant in the center of the machines spindle through the clamping system to the tool holder and tool to lead.
• - Given the flat tapered hollow shank of the tool holder and the when self-locking occurs, the possibility of opening bring high ejection power exist.

As has been explained, these demands are mentioned by the above te, known clamping device only partially and only with a high construct effort achieved.  

The tensioning device described in EP 0 451 360 A2 is even more complex tung. Here, too, clamp-like clamping pieces are provided, which Clamping shoulders or clamping surfaces inside the basic holder or Machine spindle on the one hand and the tool holder on the other with the help reach behind by claws. Again, the claws are on the side of the bottom holder caught while on the side of the tool holder Swiveling the clamping pieces are engaged. For triggering this pivoting a conical sleeve is provided, which is in axial direction tion must be postponed. This shift takes place with the help of a the sleeve screwed on clamping nut, which is from the outside via a screw gear must be turned. Here the effort is likely to be even higher than in the embodiment described in DE 39 04 259 C2.

The invention has for its object a tensioning device of the gat to create contemporary style that is simple, robust and low maintenance and thus enables an economic use, and none else Modification or reworking of the standardized tool holders according to DIN 69893 required.

This object is achieved according to the invention in a device of the above ge named type solved in that 2 clamping pieces with the help of an expanding element are connected to a clamping block, whose outer diameter in the to contracted position smaller than the smallest inside diameter so is probably the machine spindle as well as the tool holder, and that the Clamping pieces each have two clamping surfaces on both sides, which the are arranged that the four clamping surfaces of the two clamping pieces each because at angular intervals of about 90 ° on the circumference of the clamping shoulders are distributed.

This arrangement of the clamping surfaces results in a very even and symmetrical distribution of the Clamping force on the clamping shoulders of the basic holder and the tool neck ters and at the same time a symmetrical pressure distributed over the circumference force between inner cone and outer cone and between those involved End faces. This is particularly important because it means that radial loading of the clamping point by circumferential bending forces men will.  

The unit referred to in the present context as a clamping block two clamping pieces and a spreader can be assembled stood as a unit in their intended position. On on the other hand, it can also be used in simple white for control and maintenance purposes be completely removed. It is not necessary to have a large one Number of relatively complicated parts in difficult way in the basic holder or the machine spindle. The force Flow takes place in the shortest possible way and almost without the occurrence of transverse forces between the basic holder and the tool holder. Changes the standardized tool holder are not necessary.

To simplify the following explanations, it should largely only be still of the connection between a basic holder and a tool holder are spoken, although a machine instead of the basic holder spindle and a tool instead of the tool holder can be.

In a preferred embodiment, the expansion element is a differential lead screw inside the two clamping pieces in opposite coiled threaded holes. The advantage of this solution is in that a compulsion both when spreading and when contracting guidance of the clamping pieces is given. However, egg is also used as a spreader ne expansion screw into consideration, which is screwed into one of the clamping pieces and is supported on the other, or also a cone that is between the Tension pieces is pulled.

The differential thread spindle, possibly also the expansion screw, can be adjusted by ei a radial hole in the base holder with a suitable one Tool can be achieved. The differential lead screw is preferred with a detachable, non-rotatable plug connection with a plug-in unit Appropriate clamping pin connected in the radial bore of the basic holder. A second is preferably opposite provided bore in the basic holder in which an ejection pin is located, one of which is in an end blind bore of the differential thread spindle with clearance entering centering pin. The clamping pin and the ejection pins are in opposite recesses in the front sides of the standardized tool holder. They also serve as co-workers for the tool holder.  

The ejection pin preferably has a non-circular or cam-shaped one Section on and is in relation to the base of the associated recess tion of the tool holder arranged such that the tool holder through Rotation of the ejection pin using the radial outer area of the Ex center can be ejected from the basic holder.

The clamping pin and the ejection pin have the additional function that the clamping block in the relaxed position floating in the area the cutting surface of the basic holder and tool holder.

According to another preferred embodiment, one of the Clamping pieces at least one through the second clamping piece through to Ge ejection pin provided on the opposite side, which when screwing together of the clamping block with an end sloping surface on a counter surface of the tool holder strikes and ver the tool holder in the ejection direction pushes. The mentioned inclined surface can be a conical tip of the discharge pin, and the ejector pin can be threadedly engaged in the first instep piece and be adjustable in length in this way. As a counter surface in mentioned connection comes the base of one of the front Recesses of the tool holder into consideration.

According to a further preferred embodiment, the the tool holder towards the face of the clamping pieces Chen provided, which when contracting on inclined surfaces of a Intermediate piece, something of a coolant adapter that works tool holder moves in the ejection direction.

The interacting surfaces are preferably at least one Clamping shoulder and a pair of clamping claws at least partially slants, so that with radial expansion of the clamping pieces at the same time an axial Train is exerted on the tool holder.

The clamping pieces can at least on the surfaces facing each other have a recess that the passage of at least one cooling cable through the cut surface between the basic holder and the tool holder allowed.  

In the radial bores of the basic holder, the clamping pin and the Pick up ejector pin, set studs in its radial direction, the in circumferential grooves of the clamping pin and the ejection pin are screwable. In this way, the clamping pin and the output pin can be fixed in the axial direction without being hindered in the rotation his.

The prior art is supplemented by EP-B 0 172 850 and WO 88/05358 pointed out that in a similar context the use Differential threaded spindles for expanding clamping pieces gen. The publications mentioned, however, concern solutions that total are not comparable with the present problem and overall do not meet the requirements mentioned.

Further features and advantages of the invention result from the Unteran sayings.

Preferred exemplary embodiments of the invention are described below the attached drawing explained.

Fig. 1 shows a partially sectioned view of a basic holder with tool holder and clamping device in the tensioned state;

Fig. 2 is a partially sectioned view from the left in Fig. 1 and shows the cocked position of the Spannvor direction;

Fig. 3 corresponds to Fig. 2, but shows the contracted position of the clamping block;

Fig. 4 is a partial section along the line 4-4 in Fig. 1;

Fig. 5 corresponds to Fig. 1, but shows another embodiment of the ejection device;

Fig. 6 corresponds to Fig. 2, but shows the embodiment according to FIG 5 in front view.

Fig. 7 is a partial section along the line 7-7 in Fig. 5;

Fig. 8 shows a further embodiment of a Ausoßein direction;

Fig. 9a, b and c illustrate various cross-sectional shapes of the clamping shoulders.

Initially intended to FIG. 1 to 3 are received. Fig. 1 shows on the left side a basic holder 10 , in its place also, as mentioned, a machine spindle could stand, and on the right side a tool holder ter 12th The basic holder 10 has an inner cone 14 , which corresponds to an outer joint 16 of the tool holder 12 . The outer cone of the tool holder delimits a hollow shaft, in the interior of which protrudes a clamping shoulder 18 inclined at 30 ° in accordance with the aforementioned DIN 69093 standard.

The base holder 10 also has a cavity, not specifically described, in which there is an inwardly projecting clamping shoulder 20 . The clamping shoulder 20 is in the example shown opposite to the clamping shoulder 18 of the tool holder beveled at 30 °.

Within the formed by the base holder 10 and the tool holder 12 th cavity are at the top and bottom in Fig. 1 to 3 two clamping pieces 22 , 24 which are connected by a differential screw 26 to an expandable clamping block. The differential threaded spindle 26 is with oppositely coiled threaded portions 28 , 30 in threaded engagement with corresponding, not designated threaded holes of the clamping pieces 22 , 24th Rotation of the differential threaded spindle 26 thus allows the clamping pieces 22 , 24 to spread or contract. A Dre hung and tilting of the clamping pieces 22 , 24 is prevented by the fact that they lie to the left against an unspecified, circumferential paragraph inside the basic holder or are in its immediate vicinity.

The clamping pieces 22 , 24 have a substantially rectangular outline in the end view according to FIGS. 2 and 3 and form with their two outer corners four claws 32 , 34 , 36 , 38 , which are shown in more detail in FIG. 1.

As shown in Fig. 1, the clamping pieces 22 , 24 are clamp-shaped, so that they have not only the claws 32 , 34 , 36 , 38 recognizable in FIG. 2, but also four corresponding claws at the axially opposite end, from which the claws 40 and 42 can be seen in FIG. 1. The claws 32 to 42 bil four clamping surfaces on each axial side, which are also inclined at 30 ° according to the inclination of the clamping shoulders 18 , 20 . It can be seen that the radial expansion of the clamping pieces 22 , 24 causes the tool holder 2 to be drawn axially into the basic holder 10 and finally also to be expanded radially.

To rotate the differential threaded spindle 26 and thus to expand or contract the clamping pieces 22 , 24 , a clamping pin 44 is provided, which lies in a radial bore 46 of the basic holder 10 . The clamping pin 44 also runs through an end recess on the left edge of the tool holder 12 , which is specified by the standard mentioned. In this way, the clamping pin also exerts a driver function for the tool holder 12 when the base holder 10 rotates. At the radially inner end of the overall cylindrical clamping pin 44 a hexagon pin 50 protrudes inwards, which occurs in a corresponding, not designated recess from the lower end face of the differential threaded spindle 26 . Of course, a different, non-circular cross-section can be provided instead of the hexagonal cross-section. On its radially outer end face, the clamping pin also has a hexagon socket 52 , which enables the attachment of a corresponding tool for rotating the clamping pin 44 . As additionally seen in FIG. 2, the stud 44 is provided in is nem portion lying in the base holder 10 with a circumferential groove 54 into which a vertically screwed to the axis of the clamping pin 44 in the wall of the base holder 10 locking screw 56 occurs. The pin screw 56 defines in cooperation with the groove 54, the clamping pin 44 in the axial direction, but allows its rotation.

On the diametrically opposite side of the clamping pin 44 there is a further radial bore 58 in the wall of the basic holder, in which an ejection pin 60 is located corresponding to the clamping pin 44 . From the inner end of the ejection pin 60 a centering pin 62 extends radially inwards, which enters with play in an end bore 64 of the differential thread spindle 26 at its upper end in FIG. 1. With the help of the hexagon pin 50 of the tensioning pin 44 and the centering pin 42 of the ejection pin 60 , the clamping block consisting of the two tensioning pieces 22 , 24 and the differential screw 26 is in a relaxed state ( FIG. 3) floating within the cavity of the basic holder 10 and the Tool holder 12 held. As shown in FIG. 2, the ejection pin 20 is also fixed in the axial direction by a stud screw 66 . The ejection pin 60 is also in an end recess 68 of the tool holder 12 , so it also serves as a driver for rotations of the basic holder.

A further function of the ejection pin 60 is that its section 70 lying in said recess 68 , shown in cross section in FIG. 4, is non-circular and has a flattened side 72 which lies opposite the base surface of the recess 68 . When the ejection pin 60 rotates, pressure is thus exerted on the tool holder 12 to the right in FIG. 1, ie in the ejection direction. For the purpose of this rotation, the ejection pin 60 is also equipped with a hexagon socket 74 at its outer end.

Finally, FIGS. 2 and 3 show that the two clamping pieces 22 , 24 on the mutually facing sides on both sides of the differential screw 26 have corresponding semicircular recesses 76 , 78 , 80 , 82 which complement each other to form a circular cavity when the clamping pieces 22nd , 24 have contracted. These cross-sectionally circular cavities are used to hold coolant tubes 84 , 86 , which connect a coolant adapter 88 and a coolant distributor 90 , which belong to a coolant system for the cooling of the tools, which is not shown in detail.

Fig. 5 to 7 correspond essentially to Fig. 1, 2 and 4 and will therefore be explained only in terms of the deviations.

These relate to the ejection system for ejecting the tool holder 12 from the base holder 10 .

According to Fig. 5 and 6 are in the upper clamping piece 22, two ejector pins 92, 94 adjustably screwed passing through the lower clamping element 24 according to FIGS. 5 and 6 in corresponding holes not shown. The threaded handle with the upper clamping pieces 22 allows length adjustment. The lower ends of the ejection pins 92, 94 are tapered in the shape of a truncated cone, as can be seen in FIG. 6.

It is obvious that when the clamping pieces 22 , 24 are screwed together with the aid of the differential threaded spindle 26, the clamping pins 92 , 94 emerge downward from the lower clamping piece 24 . In this case, they meet as Fig. 7 shows, immediately adjacent to the periphery of the lower clamping pin 44 in the two corners of the front recess 48 of the tool holder 12 to the edges of the recess. Due to the inclined surfaces of the frustoconical ends of the ejection pins 92 , 94 , an axial pressure is exerted on the tool holder, which leads to its ejection. In this Ausoßvor gear, the entire clamping block cannot chen chen upwards in FIGS . 1 and 2, since the upper clamping piece in the upper area is supported on the clamping shoulder.

Fig. 8 is a partial view of FIG. 1 and is limited to the Veran schaulichung of the two contracted clamping pieces 22, 24 and the coolant manifold 90th The coolant distributor 90 has in the longitudinal center axis of the basic holder and the tool holder on the side facing the clamping pieces on a truncated cone-shaped projection 91 , the corre sponding, not designated recesses on the opposite surfaces of the clamping pieces 22 , 24 are assigned, which are in contraction nem Complement the condition of the clamping pieces to a conical recess. When the clamping pieces 22 , 24 contract, the corresponding inclined surfaces cause a pressure in the direction of the ejection of the tool holder to be exerted on the coolant distributor 90 , which, according to FIG. 1, lies closely against the inner surface of the tool holder.

Fig. 9a, b and c show different cross-sectional shapes of the tensioning shoulder 20 of the base holder. The representation in FIG. 9c corresponds to that of FIGS. 1 and 4. In FIG. 1, a completely radial clamping shoulder is shown in connection with a correspondingly shaped clamping surface of the clamping pieces. Fig. 9b is a combination of the two possibilities and shows a partially beveled, partially radially extending clamping shoulder.

When assembling a tool holder, the two clamping pieces 22 , 24 are first screwed together on the block using the differential screw. In this state, they can be inserted into the inside of the basic holder or the machine spindle. With the help of the tensioning pin 44 and the ejection pin 60 , they are then secured in a floating manner in their position. The tensioning device is thus functional. In this direction, they allow a tool holder to be inserted into the basic holder. The tool holder only has to be turned until the clamping pin 44 and the ejection pin 60 enter the corresponding end-side recesses 48 and 68 of the tool holder. If the clamping pin 44 is now rotated, the two clamping pieces move synchronously apart in the radial direction until the claws grip the clamping shoulders 18 , 20 of the tool holder and the basic holder or the machine spindle. The tool holder is pulled axially into the basic holder by further clamping. This creates a clamping pressure on the end face of the basic holder and the tool holder, and at the same time an increasing radial pressure, which is built up over the clamping surfaces and clamping shoulders, causes the relatively thin-walled cone of the tool holder to expand and on the inner cone of the basic holder is pressed. When he reach a predetermined torque, the clamping process is finished, and there is a positive and non-positive connection between the basic holder or machine spindle and tool holder.

The loosening takes place in reverse order. Because the inner cone of the bottom holder and the outer cone of the tool holder are relatively flat, self-liability occurs so that a separation is not automatically achieved that can. There are therefore various alternative ejections to eject beforehand facilities have been described, the function of which can already be seen in the previous description given.

Claims (15)

1. Clamping device for connecting basic holders or machine spindles with tool holders or tools for machining, with expandable, clamp-shaped clamping pieces ( 22 , 24 ), which have clamping claws projecting radially outwards ( 32 , 34 , 36 , 38 , 40 , 42 ) grip shoulder ( 18 , 20 ) in the interior of the machine spindle ( 10 ) and the tool holder ( 12 ), characterized in that 2 clamping pieces ( 22 , 24 ) are connected to a clamping block with the aid of a spreading element ( 26 ) sen outer diameter in the contracted position is smaller than the smallest inner diameter of both the machine spindle ( 10 ) and the tool holder ( 12 ), and that the clamping pieces ( 22 , 24 ) each have two clamping surfaces on both sides, which are arranged such that the four clamping surfaces of the two clamping pieces are each distributed at angular intervals of approximately 90 ° on the circumference of the clamping shoulders ( 18 , 20 ). 2. Clamping device according to claim 1, characterized in that the expanding element is a differential threaded spindle ( 26 ). 3. Clamping device according to claim 2, characterized in that the differential threaded spindle ( 26 ) is rotatable through a radial bore ( 46 ) in the machine spindle ( 10 ). 4. Clamping device according to claim 3, characterized in that the differential thread spindle ( 26 ) is connected by means of a releasable, non-rotatable plug connection with a plug-in tool allowing a clamping pin fen ( 44 ) which in the radial bore ( 46 ) of the machine spin del ( 10 ) lies. 5. Clamping device according to claim 4, characterized in that a second radial bore ( 58 ) is provided in the machine spindle ( 10 ) on the side opposite the first bore ( 46 ), in which an ejection pin ( 60 ) is located, one of which in an end blind bore ( 64 ) of the differential threaded spindle ( 26 ) with clearance adjusting pin ( 62 ). 6. Clamping device according to claim 5, characterized in that the clamping pin ( 44 ) and the ejection pin ( 60 ) lie in end-side recesses ( 48 , 68 ) on opposite sides of the tool holder ( 12 ). 7. Clamping device according to claim 6, characterized in that the clamping block ( 22 , 24 , 26 ) in the relaxed position by the clamping pin ( 44 ) and the ejection pin ( 60 ) within the cutting surface of the machine spindle ( 10 ) and tool holder ( 12 ) is kept floating. 8. Clamping device according to claim 6 or 7, characterized in that the ejection pin ( 60 ) has a non-circular section ( 70 ) which is arranged with respect to the base of the associated recess ( 68 ) of the tool holder ( 12 ) such that the tool holder ( 12 ) can be ejected from the machine spindle ( 10 ) by rotating the ejection pin. 9. Clamping device according to one of claims 1 to 7, characterized in that in one of the clamping pieces ( 22 ) at least one through the two te clamping piece ( 24 ) extending to the opposite side ejection pin ( 92 , 94 ) is provided, which when screwing the Clamping blocks ( 22 , 24 , 26 ) with an end sloping surface run onto a counter surface of the tool holder ( 12 ) and move the tool holder in the ejection direction. 10. Clamping device according to claim 9, characterized in that the ejection pin ( 92 , 94 ) has a conical tip and is held longitudinally adjustable by threaded engagement in the first clamping piece ( 22 ). 11. Clamping device according to claim 9 or 10, characterized in that the counter surface is the edge of the base of one of the end recesses ( 48 ) of the tool holder. 12. Clamping device according to one of claims 1 to 7, characterized in that the clamping pieces ( 22 , 24 ) on the side facing the tool holder ( 12 ) have at least one inclined surface which, when pulling together the clamping pieces with a corresponding inclined surface ( 91 ) of the tool holder or a piece ( 90 ) connected therewith interacts and exerts pressure on the tool holder in the ejection direction. 13. Clamping device according to one of the preceding claims, characterized in that the interacting surfaces of at least one of the clamping shoulders ( 18 , 20 ) and a pair of clamping claws ( 32 , 34 , 36 , 38 , 40 , 42 ) are at least partially chamfered. 14. Clamping device according to one of the preceding claims, characterized in that the clamping pieces ( 22 , 24 ) on the mutually facing surfaces have at least one recess ( 76 , 78 , 80 , 82 ) which the passage of at least one coolant tube ( 84 , 86 ) through the cutting surface between the machine spindle ( 10 ) and tool holder ( 12 ). 15. Clamping device according to one of claims 5 to 14, characterized in that in the radial bores ( 46 , 58 ) in the wall of the machine spindle, a threaded bore for a stud screw ( 56 , 66 ) is incorporated, which in a circumferential groove ( 54 ) of the clamping pin ( 44 ) or of the ejection pin ( 60 ) occurs.