CA2009753A1

CA2009753A1 - Device for coupling modules

Info

Publication number: CA2009753A1
Application number: CA002009753A
Authority: CA
Inventors: Grigory I. Pinkhusovich; Nikolai I. Chepelev; Gennady M. Tselkovnev; Lev P. Kuznetsov
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-02-10
Filing date: 1990-02-09
Publication date: 1990-08-10
Also published as: GB9003015D0; SE9003154D0; JPH03503865A; IT9041521A0; CN1016495B; WO1990009256A1; CN1045848A; BR9000583A; IT9041521A1; IT1238818B; DE3991591T1; RU1791075C; FR2643003A1; GB2228060B; GB2228060A; SE9003154L

Abstract

DEVICE FOR COUPLING MODULES
Abstract The invention relates to the mechanical engineering.
A device according to the invention has a screw mounted for axial movement and rotation in a first module and in a threaded hole of a shank of a second module.
According to the invention, a screw pair consisting of the screw and a threaded hole is conical and the shank is elastic and has its outside diameter in at least one section thereof greater than the diameter of a tool hole of the first module.

Description

.~ , ~97s3 .

DE~I OE ~OR COUPLING ~ODULES

~ he invention relates to the mechanical engi~eeri~g, and more specifically, it i~ concer~ed with a device for coupling modules.
~ he invention may be most advantageously u3ed for providing a set of modular tools for a complex oi machine tools such as a machining center and other NPC machine tools.
The i~Yention may also ilnd application i~
other fields of mechanical engin~ering, e.g. in case~
where a long shait is to be made up of se~eral parts.
Known in the art are devices ior coupling modules for tooling ~y~tems which are rather simple in structure and provide ior pressing a module being coupled to the end face oi 8 base module (which ha~ an outside taper to be receiYed in B tapering hole oi a machine tool spindle) by means oi one or two iastening screws threaded into radial holes of the basic module body and haYing their conical head~ which cooperate through the intermediary of variou~ inser~s wi-u~
::

~ .
, - 2 - Z(~97S3 the sur~ace of conical depressions msde in the shank of the coupled (tool) module eccentrically with respect to the hole for receiring the fastening screw.
~ hese devices ca~not, however, eliminate the radial cleara~ce between tAe cylindricsl shank of the coupled module and tool hole of the basic module which results in an unbalance, lower rigidity of a unit and poDr accuracy of positioning o~ the modules.
Also known in the art are devices for coupling mo-dules of modular tooling sy~tems (DE, C, 3448009;
GB, A, 2154479) wherein a coupled module is pressed against the end face oi a base module by means of a central pull rod through the intermediary of various wedgeshaped or spherical members. These devices are, however, difficult in the manufactùre and have a large number of components. In addition, tie-up forces are transmitted in these devices through individual points of a circle of the engageable surfaces thus compromising rigidity and reliability of the coupling.
Also known in the art is a device for coupling mo-dules in the form of combined tools, comprising a base module having a threaded hole and a tapering tool hole having an elastically deformable surface, the module being coupled having an outside cylindrical thread.
~hen the two modules are threaded together, a clearance-free radial joint and an axial pressure of the respective _ 3 _ ZX~O~r7 surfaces o~ the modules being coupled are ensured.
~ his coupling de~ic~ is, however, only applicable to tools rotating in one direction since torque developed by cutting forces upon reversal of rotation will be directed at loosening the joint. In addition, this coupling device cannot be used in modular systems for lathes where it is necessary to ensure an exact positi-oning of the tool edge with respect to the center a~is of the machi~e tool.
Known in the art is a coupling device made by SANDVIK COROMANT (DE, a, 3340320) uhich is the closest prior art of this invention.
Thi3 device ~or coupllng modules one o~ which ha3 a tool hole terminating in a datum end ~ace against ~hich bears ~ datum end ~ace of the other module having a shan~ with a threaded hole received in the tool hole of the first module, comprises a screw mounted ~or a~ial movement and rotation in the first module and in the threaded hole of the shaQk of the second module.
~his device ca~not eliminate the radial clearance ~ -~
between the cylindrical shank of the coupled module and tool hole of the base module which results in inadequate accuracy of positioning, poor rigidity o~ the assembled unit and a subs-tantial dynamic unbalance.
In all prior art systems, where it is ~ecessary to assemble a tool bar f_om ~everal (more than two) 2no97s3 modules di~erent joint designs are used 90 as to avoid direct super~osition (additiDn) o~ radial clearances, ad-ditional lowerinæ of rigidity and increase in unbalance.
~his construction can ensure versstility o~ joints neither within one and the same tool unit nor within a set of tools ~or a single machine tool the more so within a set of machine tools used in one and the same adaptive production s~stem.
Tharefore, all prior art devices feature either inadequate rigidit~, or inadequate accurac~ of module positioning, or both.
~ he invention resides in the ~act that ln a device for coupling moduleg, ~herein one module has a tool hole terminating in a datum end face against ~hich bears a datum end face of 8 second module having a shan~ -with a threaded hole received in the tool hole of the fir9t module, compriging a 9crew mounted for axial movement and rotation in tbe first module and in the threaded h~le of the sbar.~ o~ the second module to form a screw pair, according to the invention, the screw pair consisting of the screY and ~hreaded hole is made conical, the shan~ being elastic and having in at least one section thereof an outside diameter which is at least ~ .
, _5_ 2~09r7s 3 equal tD the d~ameter of the tool hole of the first module.
Owinæ tD the fact that the screw pa~r is conical and the shank is elastic and has its outside diameter at least equal to the diameter of the tool hole of the firsb module, accuracy of po9itioning and rigiditg of the Jolnt after the asscmblg are enhanced as this const-ruction guarantees a clearsnce-free joint in both radial direction and at the datum end faces since the conical screw palr transforms the axial tie-up force 1nto a radial and axLal force, l.e. there 19 the effect of 8 central wed~e ~olnt.
It has been found by wa~ of experiments that lt ls proferred that the taper in the screw pair be within the range from 2.5 to 3.5 de~rees.
The screw is preferablg provided with an elastic member en~ageable ~ith the screw hesd and with the first module in such a manner that the modules being coupled be pressed a6ainst each other at their datum end faces when the screw cooperates with the threaded hole.
The provision of the elastic member facilitates preli-minarg enea~ement of the modules up to the moment of their final coupling and also facilitates disassembly owing to potential ener~y s~ored in the ela~tic member.
The elastic member preferably cDmprises a set of ~elville springs having a tDtal compressiDn force wbich ., znos7s3 i9 greater bhan a force of friction upon couplLng of the modules ~hen they bear against each other at the datum end faces.
~ hls construction of the elastic member makes lt possible to avoid 9ventual misalignment when ongagement of the modules ~ith each otber begins and to ensure the desired compres~ion iorce with a compact deaign.
~ he device may 8190 comprise a bushins rlgidly secured in the body of the first module and bavin~ its inner surrace engageable ~ith the cylindrical surface of the screw snd one of lta end faces engageable with the elastic member.
Tbe provision of the bushing allows the screw to be insballed in tbe first module in the simplest manner and enhances relLability of en6agement of tbe ~crew with ~` the elastlc member.
; It i9 preferred that the shank of the ~econd module -~
be made ~ith radial slots deiining elastic tabs.
; Tn case the 9hank has thic~ enough wslls, 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 shan~ surface makes it possibl~ to en~urs ths coaxial ;~
position of the modules since their initial engagement .~ . . : :' .~ ...

C! " ~ ' ; ' ' _7_ ~no~r~S 3 up to the final tie-up position.
The tool hole of the first modul~ and the outer surface of the shan~ of the second module may be con-gruentl~ conical.
The provision of the conlcal tool hole and shan~
aurface facilLtates preliminar~ en~agement of the modules and their uncouplin~, and in case of an inverted cone a special rigidity oi module coupling ma~ be ensured wbich 19 necesssr~, e.~. in carrylng out the end milling.
It is preierred that in case of a non-inverted cone, the latter be with a taper of 1:10, and 1n case of an lhverted cone, the taper i9 preierabl~ 1:100.
The tool hole oi the iirst module ms~ be c~lindrical and the outer suriace of the shan~ oi the second module ma~ be conlcsl.
This con~tructlon ensures a suificLent preliminar~
alignment oi the modules in the coaxial position snd i8Ci-litate9 assembly and disas~embl~ oi the de~ice.
~ he preference given to one or another embodiment ~c~linder, non-inverted or inverted cone) of the en-ga6eable suriaces of the datum hole and shan~ depends on specific conditions of application oi a tool unit from the point of viet~ of both direction and ma~nitude oi cutting fdrces and length of bhs composite tool bar and the number of ~odules ma~i~g up this tool bar.
It is ~uite natural that con6ruence of the surfaces ,~ .
:

Z(~09753 of the dstum bole and gulde surrace of the ~han~ 1 ensured ior all embodlments of the device ~hen completel~
assembled.
~ o facilitate assembl~ and disassembly oi the ~oint, the engagesble surfaces of the modules and screw pair are preferablg made with a coefficient of sliding , friction of maximum 0.12.
The preferred coeificient of frictlon was found by ~a~ of experiment9. Ii 8 coefficient oi friction proves to be 6reater tban 0.12, both a99embly and di~ -a3sembl~ oi the devLce ~ill become a problem.
~ he invention wlll now bo described with reference to a detailed description of speclilc embodlmont9 il-lustrated in the accompan~in~ drawin~s, ln whlchs : Fl~ure 1 is a genersl view of a device for coupllne modules hav~ne a c~lindrical tool hole of a ba~ic module and a cylindrlcal guide 9urface of a shank of a coupled module, a longitudlnal sectional view;
~ Flgure 2 19 a sectional view taken along line II-II
: in Figure 1;
Fi~ure ~ is a genersl view of a device for coupling modules (at the starting tie-up moment), wherein a tool bole of a basic module is c~lindrical and a guide sur- ~ .
face of a shank of a coupled module is with a non-inverted ~ -cone (which i9 exaggerated for the sake of illustration), a longibudLnal sectional view;

.

09'753 _g_ Figure 4 is a general view of a device for coupling modules shown in Figure 3 at the moment of ti~-up when the datum end faces of the i:lodules come in toucb with each other and wben compression of an elastic member is not ~et completed and a radial clearance between the tool hole of the basic module and guide surface of the shan~ of the coupled module i9 not ~et eliminated, a longitudinal sectional view;
Figure 5 shows 8 general view of a device shown in Figure ~ at the moment of final tie-up of the mDdules wben tbe radial clearance is completel~ eliminated~
tho tie-up screw is in the limit righthand position, and tbe elastic member i9 compresssd, a longitudinal sectional view;
Figure 6 i9 a general view of a device havLng congruently engageable surfaces of the modules (non-I inverted cone) at the moment when the tie-up is completed, . . a longitudinal sectional vie~;
~; Figure 7 i9 a general view of a device having cDn-~; Eruently conical engageable surfaces (inverted cone) at the moment of complete tie-up, a longitudinal sectional vie~.
;~ As it i5 ah~olutely 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 :' ::

$;

Z~97S3 generic terms as "Dne module", "other module" or "first module", and "second module" ~ill be used in the description that follows.
A device for coupling modules according to the invention will be de9cribed with reierence tD Figure through 7.
A body of one module 1 (Figure 1) ~a9 sn lnterior space 2 having 8 tool hole 3 termLnating in its datum end ~ace 4 against which bear3 a datum end iace 5 of another module 6 having a shan~ 7 ~ith a threaded hole 8.
The shank 7 is received in tbe tool hole 3 of the module 1.
The device also has a scr~w 9 mounted for axial movement and rotation ln the module 1 and ln tbe threaded hole 8 of the shank 7 of the module 6.
According to the invention, a ~crew pair consisting of the screw 9 and threaded hola 8 ls made conlcal so as to ensure intimate engagement of tbe end faces 4 and 5 as well as outer surface of the shank 7 and the sur-face 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 shan~ 7 bas in at least one section thereof a diameter ~hich is at least equal to the diametar of the tool bole 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) .
:

Z~097s3 is im~aterial.
~ o facilitate asse~bl7 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.
Tbe screw 9 has an elastic member 11 (Figure 1) engageable with a bead 12 of the screw 9 and with the flrst module 1 in such a manner that the modules 1 and 6 being coupled are pressed again9t each Dther at their datum end faces 4 and 5 when the screw 9 cooperates ~ith the threaded hole 8.
~ he elastic member 11 i9 ln the form of 8 aet of Belville spring9 bearing a~ain9t the hsad 12 rigidly secured to the scre~ 9. The elastic member 11 may as well be in the form of one or several elastic sleeves.
It 9hould be noted that the total force of compres- :
sion of the springs (sleeves) 19 greater than an axlal force necessar~ to couple the modules 1 and 6 ln such a manner that their datum end faces 4 and 5 bear against each other.
~o ensure the axial mDvement of the screw 9 and :~ -functioning of the elastic member 11, a bushing 13 i9 rigidly secured in the body of the first mDdule 1, the end face 14 of the bushing osaring against the elastic member 11. ~he bushing 13 has its inner surface engageaole .:

with the cylindrical surface of the screw 9.
A key 15 is provided to prsvent ths modulss 1 and 6 from rotating relativs to each othsr under the action of cutt ing fDrces.
~ sealing ring 16 is provided betwe9n the bod~ 1 of the first mDdule and the head 12 of the screw.
q~he bodies of the module9 1 and 6 have central throu~h holes 17 and 18 for the pa99age of an ~llen wrench ( not shown) and fashioned 90cl~ets 19 ior an ~llen wrench are provided on eitber end of the sCrew 9, in a c9ntral hole thersof.
The tool hole 3 of the firist module 1 and the outer surface of the shanlc 7 of the second module 6 are congru-e ntl,~ c,~lindrical 90 as to ens ure the coaxial position of the modules 1 and 6 before tbe ir coupling and up to ~-the final tie-up as shown in Fig,ures 1 through 5. ~ :~
~ he tool hole 3 of the first module 1 and tbe outer surface of the shank 7 of the second module 6 are congruent-~`
ly conical a9 9hown in Figure 6 so as to facilitate theirpreliminar~ coupling and their d ise ngagement in case a non-inverted cone is used (Figure 6) or to ensure a special rigidit,~ of the module coupling which is necessary, e.g.
in carr~ing DUt the end milling in case an inverted cone i9 used (Figure 7).
~ he tool hol3 3 o~ the ~irst module 1 is c~ylindrical as shown in Fi,,rurs 3, and the outer surface of the shank 7 ~ .

..... , . ., .'. . .. ...... ;.. .. ~ . . .. ... ;.. ' . - ~ . .
, ~ .. ..... ~ . .. ....

Z~)09753 of the second module 6 is conical, with a non-inverted cone 90 as to ensure a su~ficisnt preliminar~ coaxial position o~ the modules and facilitate assemblY and disassembL~ of the device.
In case the surfaces of the tool hole 3 and shan~ 7 are made with a non-in~erted cone, the latter has a taper of 1s100 on either side.
It sbould be noted bhat the engageable surfaces of the modules 1 and 6 and of the screw pair 8 and 9 are made with a coe~ficient of sliding ~riction of ma~imum 0.12.
~ he devlce for coupllng modulss sccording to the Lnvention ~hown in Figures 3 throu~h 5 functlons ln the following manner.
When the shank 7 i9 inserted lnto the tool hole 3, the screw 9 first bears against the conical threaded hole 8. When the scre~ 9 is rotated b~ means o$ an Allen wrench (not shown) which i9 inserted through the hole 17 or 18 into soc~ets 19 on one or other side, the screw pair 8, 9 is coupled (Figure 3). The sban~ 7 has its outside diameter d in at least one section thereof which is equal bo thè diameter of the tool hole 3, and a certain resistance to assembl~ is built up as there is a clearance ~ ~
between the end faces 4 and 5. ~ -During further rotation of ths screw, the member 11- -`
bearing again3t the end face 14 of the bushing 13 will ~ -.

r,3~

be compressed and will overcome forces of friction between the outer surface of the shank 7 and tool hole 3 90 as to ensure engage~ nt of the datum end faces 4 and 5 of both modules 1 and 2 (Figure 4).
Owing to elasticit~ of the shan~ 7, the shank cannot hamper elimination of the clearance S 90 that the datum end faces 4 and 5 are pres~ed against each other ~ith a certain force F1.
During further movement of the screw 9 to the right (Figure 5) an expanslon (wedging) of the elastic shan~ 7 occur9, and the sban~ i9 completely engaged with -'-the tool hole 3, with the outer aurface thoreof, ao a8 to ensure their congruence. At the moment of complete bie-up, the modules 1 and ~ have their datum end faces 4 and 5 pressed aeain9t each other with a force ~2 greater than the initial force F1 (FLgurs 4). By thst moment the elastic member 11 has been completely compressed and maintain~ with its force full engagement Oetween the threaded surfaces of the conical scre~ pair (screw 9 and hole 8).
Owing to the com,plete and reliable engagèment of all the abovementioned surfaces maximum coaxialit~ of ~-tbe modules 1 and 6, rigidit~ of their coupling and resistance to vibrations during cutting are ensured.
~ he '~ey 15 facilitates assembl~ and prevents the mDdules 1 and 6 from ~otati4g relative to each other.

Z~)9753 The assembly (tie-up) of the modules 1 and 6 in the case of a non-inverted cone (angle c~ in Figure 6) or inverted cone (angle ~5 ir. Figure 7) i9 carried out in the same manner, with the only difference that the diameters of the shanlc 7 and hole 3 are either equal to each otber or the outside diameter of the shank 7 19 even greater thsn the diameter of the tool bole 3 in various sections ln diiferent embodiments during the initial engagement of the shank 7 with the hole 3.
If it Ls necessary to uncouple the modules 1 and 6, the screw 9 is rotated by the same ~llen l~ey Ln the oppo~lte direction 90 that first tbe en6asement of the :- shanlc 7 with tbe 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 i8 then loosened, and the shanlc 7 is moved (forced) out of ~:the hole 3 until disengagement oi the hole 8 and screw 9 `~at their threads. Further uncoupling of the modules 1 and 6 ;~.
wlll not call for specigl forces.
~i~It has been found by way of experiments that tbe device according to the invention ensures accurate pDsi-itioning of change modules in tha radial and axial direc-tions within ~0.0012 mm on the average which is much more accurate than in case OI usir.g all prior art devices for coupling modules in which an accuracy of positiDning ' . ':
, : ':
. ' ',.

G~

2009'7S3 i9 from 0.003 mm to ~ 0.006 mm Dn the average, including the prior art device made by "SANDVI~ COROMANT"
(~ 0.006 mm) referred tD abDve.
~ ests of the device according to the invention for coupling modules with an end mill of 160 mm in diameter sbo~ed high rigidit~ and quality of milling.
Ade~uate rigidity and accuracy of positioning are ensured if three or even four modules are coupled to form a single tool bar.

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Claims

1. A device for coupling modules first of which has a tool hole terminating in a datum end face and the second of which has a shank with a threaded hole received in the tool hole of the first module and has its datum end face bearing against the datum end face 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, the screw pair consisting of a screw and the threaded bole being conical and the shank being elastic and having its outside diameter in at least one section thereof which is at least equal to the diameter of the tool hole of the first module.

2. A device as claimed in claim 1, wherein a taper of said screw pair 19 from about 2.5 to about 3.5 degrees.

3. A device as claimed in claim 1, wherein said screw is provided with an elastic member engageable with a head of the screw and the first module in such a manner 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 a 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, wherein there is provided 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 said elastic member.

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

7. A device as claimed in claim 1, wherein the tool hole of the first module and the outer surface of the shank Di the second module are congruently cylindrical.

8. A device as claimed in claim 1, 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 claim 1, 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 any of claims 2, 8 or 9, wherein in case a non-inverted cone is used, the latter has a taper of up to 1:10 and in case an inverted cone is used, the latter has a taper of up to 1:100.

11. A device as claimed in claim 1, wherein the engageable surfaces of the modules and screw pair are made with a coefficient of sliding friction of maximum 0.12.