GB2265849A

GB2265849A - Coupling arrangement for rotating tool systems

Info

Publication number: GB2265849A
Application number: GB9207814A
Authority: GB
Inventors: Istvan Losonczi
Original assignee: NORMON TOOL GEP ES SZERSZAMGYA
Current assignee: NORMON TOOL GEP ES SZERSZAMGYA
Priority date: 1990-05-18
Filing date: 1992-04-09
Publication date: 1993-10-13
Also published as: HU903091D0; FR2689426A1; SE9200972D0; SE9200972L; GB9207814D0; DE4210144A1; HU60947A

Abstract

The coupling arrangement for rotating tool systems is for joining a basic body, which can be clamped in the main spindle of machine-tools, with a joining-element formed as an adapter or an extension means or a tool characterised in that the cone angle (13) of the internal cone (17) of the tapered-bore (6) is less by a predetermined amount than the cone angle (14) of the external cone of the tapered centering pin (12) and in the tapered centering pin (12) of coaxial internal cone (17) ensures simultaneous deformation of constant degree along the whole length of the joining taper surfaces, and in that the direction of the taper of the internal cone (17) is the same as the taper of the external cone of the tapered centering pin (12), while its length is longer than that of the joining taper surfaces. As the tapered-bore (6) and the tapered centering pin (12) are formed with different cones angles, the elastic deformation centrally tightens them against each other. <IMAGE>

Description

226,5849 COUPLING ARRANGEMENT FOR ROTATING TOOL SYSTEMS The invention

relates to a coupling arrangement for rotating tool systems containing a number of elements, for joining the basic body, which can be clamped in the main spindle of machine-tools, with the joining-element formed as an adapter or an extension or a tool, where in the given case, the basic body bearing the clamping shaft on one front side has a laying surface running essentially perpendicularly to the rotation axis, and a coaxial tapered-bore, while on the front side of the joining element connecting to the basic body there is also a laying surface running essentially perpendicularly to the rotation axis, and the joining element is formed with a coaxial tapered centering pin for receipt in the tapered-bore, where the tapered-bore and the tapered centering pin are formed with different cone angles and by means of elastic deformation can be centrally tightened to each other by a releasable tightening device and at the same time the laying surfaces of the basic body and the joining-element can be tightened axially against each other along a distance ring.

The formation of the main spindle and the tool holder of tool machines with automatic tool-change display a great variety.

Therefore, tool holders made of one element have been replaced by tool systems, which can be assembled from various elements. By this means can be ensured the economical supply with tools of the tool machines both in the view of the manufacturers and the consumers. To a given type of basic body can be joined the tool holder most suitable for the working task, which can also be disassembled and used again later for another purpose.

Tool holder devices with more elements are known per se, wherein the connecting elements are formed generally so that the centering pin formed in one element connects to the coaxial bore of the other element.

In the case of a known version, which is described in HU-PS 188 534, one of the joint elements is formed with a central bore, while the other one has a centering pin fitting thereto and 2 both of them are provided with a f ixing, respectively driving, element, where one of the elements has a uniaxial threaded bore attaching to the central bore and the other element is also provided with a central threaded bore. The geometrical pitch ratio of the threaded bore is 1:2, and to the two threads is joined a differential screw ensuring the fixing and loosing of the tightening system. In this system, faults in the joint between the pin and the bore reduce the circular running accuracy and, in addition, the threads have to be made with great accuracy to avoid the jamming of the differential screw.

According to another solution, known from DE-OS 3 131 478, the connection of the elements is ensured by the centering pin and the bore, respectively the screw of tapered end arranged perpendicularly to their axis, which is tightened into the tapered die of the centering pin. This joint - as the fastening force is not concentric - does not result either in a perfectly plain laying surface or in the circular running accuracy of the joint.

In a further known solution, described in DE-PS 3 314 591, the coupling arrangement contains a basic body bearing the clamping shaft. Furthermore, the basic body has, on one of the front sides, a front surface perpendicular to the rotation axis and a coaxial tapered clamping bore, respectively a joining element formed as a tool bearer, which is provided on its one front side with-a front surface also perpendicular to the rotation axis as well as with a centering pin, which through an attached and coaxial external cone, besides an elastic deformation of a part with the longitudinal displacement of the slip between the cones can be centralised in the clamping bore. Furthermore, it contains a releasable tightening device for tightening the laying surfaces of the basic body and the joining element axially against each other. In this formation, the smallest diameter of the external cone joins firstly to the tapered bore, and as a result the stability of the connection is not so satisfactory. The elastic deformation takes place completely by the angle deviation between the two cones, and consequently it can occur that the two 3 cones do not fit properly to each other, but the front surfaces of the front side are fitting, which can have a disadvantageous effect from the point of view of the circular running accuracy and the stability (torque transmission, slip). Inside of the external cone, there is a threaded bore, and, by this means, in the front part and in the end part of the fitting cone, the deformation capability of the system is not identical, whereby it requires intensive working accuracy.

The present invention is aimed at the elimination of the above mentioned shortcomings, respectively at reducing the need for working accuracy and at the formation of such a coupling arrangement, in which the connection ensures good circular running accuracy, fixation, respectively the large-sized and stabilised elastic deformation along the taper and a simple construction, whereby it can be economically produced.

According to the invention, a coupling arrangement of the kind defined above is characterised in that the cone angle of the internal cone of the tapered-bore is less by a predetermined amount than the cone angle of the external cone of the tapered centering pin, and in the tapered centering pin there is a coaxial internal cone ensuring the simultaneous deformation of constant degree along the whole length of the joining taper surfaces, wherein the direction of the taper of the internal cone is the same as the taper of the external cone of the tapered centering pin, while its length is longer than that of the joining taper surfaces.

At the beginning of the fitting between the two laying surfaces there is a slit. In the first stage of the elastic deformation, the two cones are entirely fitting (the cone angles are equalised). However, at this time, between the front surfaces there is still a slit.

In the second stage, the slit arising from the accuracy of manufacture has to be eliminated so that the stress caused by the deformation should be constant along the whole length of the cone.

This can be ensured in that in the tapered centering pin an 4 internal cone is formed so that the internal cone should be longer than the length of the fitting cone, and the direction of its conicity should be the same as that of the external cone, while the length of the cone can be determined by dimensioning the deformation. At the inner end of said internal cone expediently a circular recess is arranged in order to eliminate the distortion of the deformation capability of the centering pin forced for elastic deformation, which deformation is caused by the stationary connection between the centering pin and the joining element. On eliminating the slit, the greatest diameter of the two laying surfaces essentially perpendicular to the rotation axis join. This is carried out by means of the slightly tapered formation of each laying surface.

In the third stage of the deformation, the formation of the two laying surfaces changes, whereby a circular ring of increasing surface starting from the greatest diameter comes into being. The so- realised connection from the point of view of the rotation, is perfect, and it is also the most suitable for the torque transmission, as the system joins with proper tightness not only at the taper but on the laying surfaces as well, which influences advantageously the bending strength of the system. The invention is described in detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a coupling arrangement according to the 25 invention comprising a basic body bearing a chucking shuft and a joining element coupled thereto seen in axial section, while Figure 2 represents the coupling part on a larger scale. Figure 1 shows the basic body 1 with a rotation axis 2 bearing a coaxial external cone 3, which is formed in accordance with the given specification of the machine tool. On the front side of the basic body I can be found a laying surface 4 running essentially perpendicular to the rotation axis, which laying surface 4 is slightly tapered with an angle of inclination 5 as shown in Figure 2, and is joined with a tapered-bore 6 coaxial with the rotation axis 2 through a rounded transition 7. which is advantageous, due to the grinding of the laying surface 4. To the basic body 1 is joined a joining element 8 formed primarily as a tool holder. On one of its front sides, a front surface 9 is slightly tapered in accordance with the angle of inclination 10 and can be found running perpendicularly to the rotation axis 2. The laying surface is joined, through an annular recess 11, to a tapered centering pin 12 coaxial with the rotation axis 2. The joint is formed so that the cone angle 13 of the tapered-bore 6 is smaller than the cone angle 14 of the tapered centering pin 12, the difference being not more than 2 minutes. By this means, the two cones meet on the possible greatest diameter, being in the axial section 15. In the home position of the joint between the laying surface 4 and 9 can be found a slit. Inside the tapered is centering pin 12, an internal cone 17 is formed coaxial with the rotation axis 2, where the cone angle 18 is determined so that between the axial sections 15 and 19 the def ormation- capability of the system is stabilised. Both the internal cone of the tapered bore 6 and the tapered centering pin 12 are deformable. The steadiness of the deformation can be better promoted if the length of the internal cone 17 is longer than the length of the cone fitting between the axial sections 15 and 19. The internal cone 17 is connected through a recess 39 and the front surface 24 of the joining element 8, an internal threaded bore 20 coaxial with the rotation axis, which bore is necessary for the fixing and releasing of the basic body 1 with the joining element 8. The internal threaded bore 20 is joined to a cone-drawing pin 21 provided with a threaded end 22. During coupling, the front surface 23 of the cone-drawing pin 21 is supported on the front surface 24 of the joining element 8 joined to the internal cone 17 through the recess 39. The cylindrical surface 25 of the cone-drawing pin 21 is loosely within a cylindrical bore 26, coaxial with the rotation axis 2, of the basic body 1. On the cone-drawing pin 21, an annular V- shaped recess 27 is formed for the fixing and releasing of the system. In the basic body 1, a 6 threaded bore 28 is arranged perpendicular to the rotation axis 2. Into the threaded bore 29 is fitted a grub screw 29 of tapered end, which can be moved by means of an internal key-hole 30. The cone angle of the grub screw 29 is greater than the cone angle of the V-shaped recess 27 of the cone-drawing pin 21, and therefore the two elements will meet on the pointed edge 31 of the cone-drawing pin 21. In the cone-drawing pin 21, an internal key-hole 32 is expediently arranged, respective an internal bore 33, through which cooling mixture is forwarded to the cutting edge.

In the case of such tool systems, it is an essential requirement that the cutting edge of the single-point cutting tool should get to a predetermined position considering the compass element of the main spindle so that the tool should be able to 15raise the cutting edge moving away from the surface. Therefore, a bore 34 is made in a predetermined place on the laying surface 4.considering the compass surface 36 of the basic body 1. Facing thereto, on the laying surface 9 of the joining element 8 on the same pitch circle, a bore 35 of the same dimension is provided. In the two bores 34, 35 a guiding pin 37 is loosely received, which is held by a slotted spring 38 against dropping out. The guiding pin 37 serves also for ensuring the system. At extraordinarily great torques, the frictional force generated on the fitting surfaces may not be sufficient for bearing the load, and at that time, the guiding pin 37 is in the position to adopt the load, while using shear. As far as the guiding pin 37 is concerned, either one or more than one can be placed on the centre circle. However, You have to take care of the fact that the split should be unequal, and the two elements, i.e. the basic body 1 and the joining element 8, could be joined in any way ensuring the described position of the cutting edge.

The coupling arrangement according to the invention operates as follows. Into the joining element 8 is screwed the cone-drawing pin 21 with the aid of the internal key-hole 32. The so-assembled joining element 8 is placed into the basic body 1, when the 7 internal cone of the tapered-bore 6 joins with the external cone of the tapered centering pin 12 on the greatest diameter of the axial section 15. At this time there is a slit between the laying surfaces 4 and 9. Then the grub screw 29 of tapered end is moved in towards the rotation axis 2 with the aid of the internal key-hole 30, so that it will connect with the pointed edge 31 of the cone-drawing pin 21. At this time, owing to the clearance between the cylindrical bore 26 and the cylindrical surface 25, the cone-drawing pin 21 inclines and the two surfaces join each other. As the cone-drawing pin 21 joins the joining element 8 only at the threaded end 22 and through the front surface, 23 the cone-drawing pin 21 is not able to pull away, so the tapered centering pin 12 joins centered further on to the tapered-bore 6 of the basic body 1. With further movement of the grub screw, elastic deformation starts. In the first stage, the angle difference between the two cones, which is not more than two minutes, will be equalised. At the time, between the front surfaces 4 and 9 a slit 16 can be still found. In the second stage of the deformation, the formation of the system between the axial sections 15 and 19 changes uniformly, and as a consequence, the slit 16 disappears. As the front surfaces 4 and 9 with the angles of inclination 5 and 10 are slightly tapered, at first their greatest diameters only will meet each other. In the third stage, further movement of the grub screw towards the rotation axis 2 causes the formation of the laying surfaces 4 and 9 to change elastically, so that from their greatest diameter towards the rotation axis 2, they tighten against each other on an increasing circle ring.

In such a way, a joint of great circular running accuracy can be realised, as, between the axial sections 15 and 19, the two joining tapered surfaces lie entirely on each other. in addition the system is suitable for bearing great loads as well, as the front laying surfaces are also joined besides the tapers.

With a suitable choice of the cone angle 18 of the internal cone 17 of the centering pin 12, the surface pressure generated 8 along the cones can be stabilised and simultaneously, the working accuracy of the centering pin 21 and the tapered-bore 6 can be decreased. As a consequence, the economic efficiency improves.

As can be seen from the described example, the solution according to the invention enables a rapid and safe joint to be realised wherein the tightening and releasing can be effected from the radial direction. By this means, there is no need to take the basic body out from the tool machine, and at the same time, the formation is simple and can be relatively easily manufactured. The joining elements are interchangeable, enabling the use of optional element combinations and ensure the assembling of the optimal tool system.

Although, in the description only one embodiment has been described for realising the coupling arrangement according to the invention, obviously, various modifications can also be effected within the scope of the claims.

In the annexed claims, reference numbers have been used purely by way of example in order to facilitate comprehension but it is hereby declared that absolutely no limitation of scope whatsoever is intended thereby.

9

Claims

CLAIMS 1. Coupling arrangement for rotating tool systems for joining a

basic body, which can be clamped in the main spindle of the machine-tool, with a joining-element formed as an adapter or an extension means or a tool, where optionally the basic body bearing the clamping shaft on one front side has a laying surface running essentially perpendicularly to the rotation axis, and a coaxial tapered- bore, while on the front side of the joining element for connection to the basic body there is also a laying surface running essentially perpendicularly to the rotation axis, and the joining element is formed with a coaxial tapered centering pin for receipt in the tapered-bore, where the tapered-bore and the tapered centering pin are formed with different cone angles and by means of elastic deformation can be centrally tightened to each other by a releasable tightening device, and at the same time the laying surfaces of the basic body and the joining-element can be tightened axially against each other along a distance ring, characterised in that the cone angle (13) of the internal cone (17) of the tapered-bore (6) is less by a predetermined amount than the cone angle (14) of the external cone of the tapered centering pin (12), and in the tapered centering pin (12) there is a coaxial internal cone (17) ensuring the simultaneous deformation of constant degree along the whole length of the joining taper surfaces, wherein the direction of the taper of the internal cone (17) is the same as the taper of the external cone of the tapered centering pin (12), while its length is longer than that of the joining taper surfaces.
2 Coupling arrangement according to claim 1. characterised in that the difference between the angle values of the cone angles (13, 14) is not more than two minutes.
3. Coupling arrangement according to claim I or 2, characterised in that during tightening of the internal cone of the tapered-bore (6) with the external cone of the tapered centering pin (12) with elastic deformation, there is a slit (10) between the two laying surfaces (4, 9).
4. Coupling arrangement according to any one claims 1 to 3, characterised in that both of the laying surfaces (4, 9) are slightly tapered, and that the angle value is not more than one minute.
5. Coupling arrangement according to any one claims 1 to 4, characterised in that on the inner end of the internal cone (17) of the tapered centering pin (12) a circular recess (39) is 10 formed.
6. Coupling arrangement according to any of the claims 1 to 5, characterised in that both the tapered-bore (6) and the tapered centering pin (12) are exposed to elastic deformation and the degree of the simultaneous deformation of these elements along the whole length of the joining taper surfaces respectively between the axial sections (15, 19) limiting the said length, is constant.
7. Coupling arrangement substantially as herein particularly described with reference to and as illustrated in the accompanying drawings.