GB2228060A

GB2228060A - Rotary coupling.

Info

Publication number: GB2228060A
Application number: GB9003015A
Authority: GB
Inventors: Nikolai Ivanovich Chepelev; Gennady Mikhailovic Tselkovnev; Lev Petrovich Kuznetsov; Grigory Iosifovic Penkhusovich
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-02-10
Filing date: 1990-02-09
Publication date: 1990-08-15
Anticipated expiration: 2010-02-09
Also published as: SE9003154D0; CA2009753A1; FR2643003A1; WO1990009256A1; CN1016495B; DE3991591T1; RU1791075C; SE9003154L; JPH03503865A; BR9000583A; GB2228060B; IT9041521A1; GB9003015D0; IT9041521A0; IT1238818B; CN1045848A

Abstract

The device comprises a screw (9) mounted with the possibility of axial movement and rotation in the first module (1) and in a threaded opening (8) of the shank (7) of the second module (6). According to the invention the screw pair - the screw (9) and the threaded opening (8) - is made conical, whereas the shank (7) is made elastic and in at least one cross-section has a diameter which is no smaller than that of the fitting opening (3) of the first module (1).

Description

DEVICE FOR COUPLING MODULES The invention relates to the mechanical engineering, and more specifically, it is concerned with a device for coupling modules.

The invention may be most advantageously used for providing a set of modular tools for a complex of machine tools such as a machining center and other NPC machine tools.

The invention may also find application in other fields of mechanical engineering, e.g. in cases where a long shaft is to be made up of several parts.

The invention resides in the fact that in a device for coupling modules, wherein one module has a tool hole terminating in a datum end face against which bears a datum end face of a second module having a shank with a threaded hole received in the tool hole of the first module, comprising a screw mounted for axial movement and rotation in the first module and in the threaded hole of the shank of the second module to form a screw pair, according to the invention, the screw pair consisting of the screw and threaded hole is made conical, the shank being elastic and having in at least one section thereof an outside diameter which is at least equal to the diameter of the tool hole of the first module.

Owing to the fact that the screw pair is conical and the shank is elastic and has its outside diameter at least equal to the diameter of the tool hole of the first module, accuracy of positioning and rigidity of the joint after the assembly are enhanced as this construction guarantees a clearance-free joint in both radial direction and at the datum end faces since the conical screw pair transforms the axial tie-up force into a radial and axial force, i.e. there is the effect of a central wedge joint.

It has been found by way of experiments that it is preferred that the taper in the screw pair be within the range from 2.5 to 3.5 degrees.

The screw is preferably provided with an elastic member engageable with the screw head and with the first module in such a manner that the modules being coupled be pressed against each other at their datum end faces when the screw cooperates with the threaded hole.

The provision of the elastic member facilitates preliminary engagement of the modules up to the moment of their final coupling and also facilitates disassembly owing to potential energy stored in the elastic member.

The elastic member preferably comprises a set of Belville springs having a total compression force which is greater than a force of friction upon coupling of the modules when they bear against each other at the datum end faces.

This construction of the elastic member makes it possible to avoid eventual misalignment when engagement of the modules with each other begins and to ensure the desired compression force with a compact design.

The device may also comprise a bushing rigidly secured in the body of the first module and having its inner surface engageable with the cylindrical surface of the screw and one of its end faces engageable with the elastic member.

The provision of the bushing allows the screw to be installed in the first module in the simplest manner and enhances reliability of engagement of the screw with the elastic member.

It is preferred that the shank of the second module be made with radial slots defining elastic tabs.

In case the shank has thick enough walls, this design ensures a sufficient elasticity of the shank.

It is generally preferred that the tool hole of the first module and the outer surface of. the shank of the second module be congruently cylindrical.

The cylindrical shape of the tool hole and of the shank surface makes it possible to ensure the coaxial position of the modules since their initial engagement up to the final tie-up position.

The tool hole of the first module and the outer surface of the shank of the second module may be con gruently conical.

The provision of the conical tool hole and shank surface facilitates preliminary engagement of the modules and their uncoupling, and in case of an inverted cone a special rigidity of module coupling may be ensured which is necessary, e.g. in carrying out the end milling.

It is preferred that in case of a non-inverted cone, the latter be with a taper of 1:10, and in case of an inverted cone, the taper is preferably 1:100.

The tool hole of the first module may be cylindrical and the outer surface of the shank of the second module may be conical.

This construction ensures a sufficient preliminary alignment of the modules in the coaxial position and facilitates assembly and disassembly of the device.

The preference given to one or another embodiment (cylinder, non-inverted or inverted cone) of the engageable surfaces of the datum hole and shank depends on specific conditions of application of a tool unit from the point of view of both direction and magnitude of cutting forces and length of the composite tool bar and the number of modules making up this tool bar.

It is quite natural that congruence of the surfaces of the datum hole and guide surface of the shank is ensured for all embodiments of the device when completely assembled.

To facilitate assembly and disassembly of the joint, the engageable surfaces of the modules and screw pair are preferably made with a coefficient of sliding friction of maximum 0.12.

The preferred coefficient of friction was found by way of experiments. If a coefficient of friction proves to be greater than 0.12, both assembly and diz assembly of the device will become a problem.

The invention will now be described with reference to a detailed description of specific embodiments il- lustrated in the accompanying drawings, in which: Figure 1 is a general view of a device for coupling modules having a cylindrical tool hole of a basic module and a cylindrical guide surface of a shank of a coupled module, a longitudinal sectional view; Figure 2 is a sectional view taken along line II-II in Figure 1; Figure 3 is a general view of a device for coupling modules (at the starting tie-up moment), wherein a tool hole of a basic module is cylindrical and a guide surface of a shank of a coupled module is with a non-inverted cone (which is exaggerated for the sake of illustration), a longitudinal sectional view;; Figure 4 is a general view of a device for coupling modules shown in Figure 3 at the moment of tie-up when the datum end faces of the nodules come in touch with each other and when compression of an elastic member is not yet completed and a radial clearance between the tool hole of the basic module and guide surface of the shank of the coupled module is not yet eliminated, a longitudinal sectional view; Figure 5 shows a general view of a device shown in Figure 3 at the moment of final tie-up of the modules when the radial clearance is completely eliminated, the tie-up screw is in the limit righthand position, and the elastic member is compressed, a longitudinal sectional view; ; Figure 6 is a general view of a device having congruently engageable surfaces of the modules (non inverted cone) at the moment when the tie-up is completed, a longitudinal sectional view; Figure 7 is a general view of a device having congruently conical engageable surfaces (inverted cone) at the moment of complete tie-up, a longitudinal sectional view.

As it is absolutely unimportant for application of the present invention what modules (basic, intermediate, tool) are coupled to one another using the device according the invention in view of versatility of the device, such generic terms as "one module", "other module" or "first module", and "second module" will be used in the description that follows.

A device for coupling modules according to the invention will be described with reference to Figures 1 through 7.

A body of one module 1 (Figure 1) has an interior space 2 having a tool hole 3 terminating in its datum end face 4 against which bears a datum end face 5 of another module 6 having a shank 7 with a threaded hole 8.

The shank 7 is received in the tool hole 3 of the module 1.

The device also has a screw 9 mounted for axial movement and rotation in the module 1 and in the threaded hole 8 of the shank 7 of the module 6.

According to the invention, a screw pair consisting of the screw 9 and threaded hole 8 is made conical so as to ensure intimate engagement of the end faces 4 and 5 as well as outer surface of the shank 7 and the surface of the tool hole 3 during tie-up of the modules 1 and 6.

In addition, according to the invention, the outer surface of the shank 7 has in at least one section thereof a diameter which is at least equal to the diameter of the tool hole 3. It should be noted that a taper in the screw pair should be within the range from about 2.5 to about 3.5 degrees. The hand of the thread (right or left) is immaterial.

To facilitate assembly of the device and to eliminate radial clearances, the shank 7 is made elastic by making it thin-walled or by providing radial slots 10 (Figure 2) defining elastic tabs.

The screw 9 has an elastic member 11 (Figure 1) engageable with a head 12 of the screw 9 and with the first module 1 in such a manner that the modules 1 and 6 being coupled are pressed against each other at their datum end faces 4 and 5 when the screw 9 cooperates with the threaded hole 8.

The elastic member 11 is in the form of a set of Belville sprints bearing against the head 12 rigidly secured to the screw 9. The elastic member 11 may as well be in the form of one or several elastic sleeves.

It should be noted that the total force of compression of the springs (sleeves) is greater than an axial force necessary to couple the modules 1 and 6 in such a manner that their datum end faces 4 and 5 bear against each other.

To ensure the axial movement of the screw 9 and functioning of the elastic member 11, a bushing 13 is rigidly secured in the body of the first module 1, the end face 14 of the bushing bearing against the elastic member 11. The bushing 13 has its inner surface engageable with the cylindrical surface of the screw 9.

A key 15 is provided to prevent the modules 1 and 6 from rotating relative to each other under the action of cutting forces.

A sealing rinOP 16 is provided between the body 1 of the first module and the head 12 of the screw.

The bodies of the modules 1 and 6 have central through holes 17 and 18 for the passage of an Allen wrench (not shown) and fashioned sockets 19 for an Allen wrench are provided on either end of the screw 9, in a central hole thereof.

The tool hole 3 of the first module 1 and the outer surface of the shank 7 of the second module 6 are congruently cylindrical so as to ensure the coaxial position of the modules 1 and 6 before their coupling and up to the final tie-up as shown in Figures 1 through 5.

The tool hole 3 of the first module 1 and the outer surface of the shank 7 of the second module 6 are congruently conical as shown in Figure 6 so as to facilitate their preliminary coupling and their disengagement in case a non-inverted cone is used (Figure 6) or to ensure a special rigidity of the module coupling which is necessary, e.g.

in carrying out the end milling in case an inverted cone is used (Figure 7).

The tool hole 3 of the first module 1 is cylindrical as shown in Figure 3, and the outer surface of the shank 7 of the second module 6 is conical, with a non-inverted cone so as to ensure a sufficient preliminary coaxial position of the modules and facilitate assembly and disassembly of the device.

In case the surfaces of the tool hole 3 and shank 7 are made with a non-inverted cone, the latter has a taper of 1:100 on either side.

It should be noted that the engageable surfaces of the modules 1 and 6 and of the screw pair 8 and 9 are made with a coefficient of sliding friction of maximum 0.12.

The device for coupling modules according to the invention shown in Figures 3 through 5 functions in the following manner.

When the shank 7 is inserted into the tool hole 3, the screw 9 first bears against the conical threaded hole 8. When the screw 9 is rotated by means of an Allen wrench (not shown) which is inserted through the hole 17 or 18 into sockets 19 on one or other side, the screw pair 8, 9 is coupled (Figure 3). The shank 7 has its outside diameter d in at least one section thereof which is equal to the diameter of the tool hole 3, and a certain resistance to assembly is built up as there is a clearance o between the end faces 4 and 5.

During further rotation of the screw, the member 11 bearing against the end face 14 of the bushing 13 will be compressed and will overcome forces of friction between the outer surface of the shank 7 and tool hole 3 so as to ensure engagement of the datum end faces 4 and 5 of both modules 1 and 2 (Figure 4).

Owing to elasticity of the shank 7, the shank cannot hamper elimination of the clearance S so that the datum end faces 4 and 5 are pressed against each other with a certain force F1.

During further movement of the screw 9 to the right (Figure 5) an expansion (wedging) of the elastic shank 7 occurs, and the shank is completely engaged with the tool hole 3, with the outer surface thereof, so as to ensure their congruence. At the moment of complete tie-up, the modules 1 and 6 have their datum end faces 4 and 5 pressed against each other with a force F2 greater than the initial force F1 (Figure 4). By that moment the elastic member 11 has been completely compressed and maintains with its force full engagement between the threaded surfaces of the conical screw pair (screw 9 and hole 8).

Owing to the complete and reliable engagement of all the abovementioned surfaces maximum coaxiality of the modules 1 and 6, rigidity of their coupling and resistance to vibrations during cutting are ensured.

The key 15 facilitates assembly and prevents the modules 1 and 6 from rotating relative to each other.

The assembly (tie-up) of the modules 1 and 6 in the case of a non-inverted cone (angle > , in Figure 6) or inverted cone (angle 9 in Figure 7) is carried out in the same manner, with the only difference that the diameters of the shank 7 and hole 3 are either equal to each other or the outside diameter of the shank 7 is even greater than the diameter of the tool hole 3 in various sections in different embodiments during the initial engagement of the shank 7 with the hole 3.

If it is necessary to uncouple the modules 1 and 6, the screw 9 is rotated by the same Allen key in the opposite direction so that first the engagement of the shank 7 with the hole 3 is loosened (which is facilitated owing to potential energy stored in the elastic member 11), the engagement between the datum end faces 4 and 5 is then loosened, and the shank 7 is moved (forced) out of the hole 3 until disengagement of the hole- 8 and screw 9 at their threads. Further uncoupling of the modules 1 and 6 will not call for special forces.

It has been found by way of experiments that the device according to the invention ensures accurate positioning of change modules in the radial and axial directions within +0.0012 mm on the average which is much more accurate than in case of using all prior art devices for coupling modules in which an accuracy of positioning is from 0.003 mm to t 0.006 mm on the average, including the prior art device made by "SANDVIK COROLtANT" Ct 0.006 mm) referred to above.

Tests of the device according to the invention for coupling modules with an end mill of 160 mm in diameter showed high rigidity and quality of milling.

Adequate rigidity and accuracy of positioning are ensured if three or even four modules are coupled to form a single tool bar.

Claims

CLAIMS:

1. A device for coupling modules, the first module of which has a tool hole with a datum end face, and the second module of which has a shank for reception in the tool hole of the first module with a datum face bearing against the datum end face of the first module the said shank itself having an internally threaded hole, the device comprising a screw member mounted for axial movement and rotation in the first module and within the threaded hole of the shank of the second module, the screw pair, consisting of the said screw member and the internally threaded hole, being conical and the shank being radially elastic with an outside diameter over at least part thereof which is equal to the diameter of the tool hole of the first module.

2. A device as claimed in claim 1, wherein the taper of said screw pair is from about 2.5 to about 3.5 degrees.

3. A device as claimed in claim 1, wherein said screw member has a radially extending head and an elastic member located between the head of the screw and the first module in such a manner as to ensure that the datum end faces of the coupled modules are pressed against each other when the screw cooperates with the threaded hole.

4. A device as claimed in claim 3, wherein said elastic member is made in the form of a set of Belville springs having a total compression force which is greater than that force necessary to couple the modules in such a manner that their datum end faces bear against each other.

5. A device as claimed in claim 3 or 4, wherein there is provided a bushing rigidly secured within the body of the first module and having its inner surface slidingly engageable with the cylindrical surface of the screw and one of its end faces engageable with said elastic member.

6. A device as claimed in claim 1, wherein said shank is made with radial slots defining radially elastic fingers thereof.

7. A device as claimed in any one preceding claim wherein the tool hole of the first module and the outer surface of the shank of the second module are congruently cylindrical.

8. A device as claimed in any one of preceding claims 1 to 6, wherein the tool hole of the first module and the outer surface of the shank of the second module are congruently conical.

9. A device as claimed in any one preceding claims 1 to 6 wherein the tool hole of the first module is cylindrical and the outer surface of the shank of the second module is conical.

10. A device as claimed in claim 2 wherein if a non-inverted cone is used, the later has a taper of up to 1:10 and if an inverted cone is used, the latter has a taper of up to 1:100.

11. A device as claimed in any one preceding claim, wherein the engageable surfaces of the modules and screw pair are made with a coefficient of sliding friction of maximum 0.12.

12. A device for coupling modules as described with reference to the accompanying drawings.