US3209557A

US3209557A - Circular knitting machine

Info

Publication number: US3209557A
Application number: US187395A
Authority: US
Inventors: Lagerweij Arnoldus Gerardus
Original assignee: EUROSTOCK ANSTALT
Current assignee: EUROSTOCK ANSTALT
Priority date: 1961-10-12
Filing date: 1962-04-13
Publication date: 1965-10-05
Anticipated expiration: 1982-10-05
Also published as: FR1310830A; AT261787B; GB1013784A; ES286823A1; ES90765U; DE1850107U; LU41166A1; CH370516A; ES274959A1; DE1228366B; ES274958A1; BE617431A; NL270187A

Description

Oct. 5, 1965 A. G. LAGERWEIJ 3,209,557

CIRCULAR KNITTING MACHINE Filed April 15, 1962 5 Sheets-Sheet 1 I N VE NTO R Awnoidzzs fiewardr rlayem ey ATTORNEYS Oct. 5, 1965 A. G. LAGERWEIJ 3,209,557

CIRCULAR KNITTING MACHINE Filed April 13, 1962 5 Sheets-Sheet 2 INVENTOI Q 4? ??0/052? fiemmzks layerwey ATTORNEYS Oct. 5, 1965 A. G. LAGERWEIJ CIRCULAR KNITTING MACHINE 5 Sheets-Sheet 5 Filed April 13, 1962 A w w g Oct. 5, 1965 A. e. LAGERWEIJ 3,209,557

CIRCULAR KNITTING MACHINE Filed April 15, 1962 5 ShEJGtS-She't 4 ATTORNEYS Oct. 5, 1965 Filed April 15, 1962 A. G. LAGERWEIJ CIRCULAR KNITTING MACHINE 5 Sheets-Sheet 5 WWII/[Ill INVENTOR ATTORNEYS United States Patent 3,209,557 CIRCULAR KNITTING MACHINE Arnoldus Gerardus Lagerweij, The Hague, Netherlands, assignor to Eurostock Anstalt, Vaduz, Liechtenstein, a corporation of Liechtenstein Filed Apr. 13, 1962, Ser. No. 187,395 Claims priority, application Netherlands, Oct. 12, 1961, 270,187; Jan. 3, 1962, 273,134 'Claims. (Cl. 6654) The invention relates to a circular knitting machine with a rotary needle cylinder, which is fitted with latch needles and with sinkers placed between the needles, said machine being further equipped with slots and/ or cams for moving the needles and the sinkers, with a selector device for selectively bringing the needles in a higher or a lower position before the stitch cam, and with adjusting means for adjusting during a particular revolution of the cylinder the distance between the line joining the Points of support of the yarn on two adjacent sinkers and the head of the needle between them in the lowermost point of the needle movement to a higher value than during other revolutions.

In an earlier proposal a similar machine is described, in which the distance between the points of support of the yarn on two adjacent sinkers and the head of the needle between them can be increased by adjusting a movable sinker cam with different guiding paths for two types of sinker into a position such that one type of sinker moves further inwards than the other type. Consequently, with one type of sinker the yarn comes to rest on the normal supporting surface and with the other type of sinker on top of the sinker, as a result of which the line joining the points of support of the yarn on the two sinkers is upwardly inclined. When the movable sinker cam is being adjusted to this position, a knitting flaw is produced, because the duration of the movement of the sinker cam extends over about 20 sinkers and said sinkers thus travel past in a faulty intermediate position. On account of the fact that the needles and sinkers are closely packed and the speed of revolution of the needle cylinder is great this flaw cannot be kept small. If during the production of a continuous piece of knitting no adjustment is required, the above system is suitable, but if, for instance, after each revolution or after every two revolutions of the needle cylinder the adjustment has to be changed, a useless product is obtained.

The object of the invention is to eliminate the undesirable operation as outlined above in a manner hereafter set forth. This object is achieved, in accordance with the present invention, by-avoiding deviations in the movement of the previously mentioned needles and/ or sinkers during critical periods of the operative cycle.

In one embodiment of the apparatus the said means consist of two cams, which can be brought into the slot of the sinker cam or of the stitch cam and each of which acts on the sinkers'or the needles respectively of a part of the cylindrical surface of the needle cylinder, while each of said cams can be displaced during the inoperative period.

In another embodiment the said means consist of a cam which can be brought into the slot of the sinker cam or of the stitch cam during slightly more than one full revolution of the needle cylinder and can also be displaced in the direction transverse to its main plane of movement so that in the overlapping parts of the revolution it will take up two adjacent positions, in which it alternately does and does not engage the corresponding sinkers or needles respectively.

In yet another embodiment the needles and/or the sinkers are equipped with an additional butt, while cams are present which are able to cooperate with the additional butt of the needles and/or the sinkers, the cams being adapted to be moved into and out of their operative position during a part of the revolution of the needle cylinder when no additional butt is facing the cam in question.

On a machine according to the invention, even if it contains only one feed position, it is possible to produce flawlessly several patterns for which hithereto machines with more than one feed position were required. Moreover the drawback of a machine with two feed positions is thus avoided, viz. the drawback that it requires a needle cylinder with an odd number of needles if patterns are to be produced for which constantly changing settings are necessary. The same patterns can be produced on a machine with one feed position with a conventional needle cylinder with an even number of needles. However, it also is pos sible to use the present invention in a machine having more than one feed position.

The invention will now be explained more fully with reference to the drawings.

FIG. 1 shows a longitudinal cross-section of a part of a knitting machine according to the invention.

FIGS. 2, 3 and 4 show three types of sinker for the machine acocrding to FIG. 1.

FIG. 5 shows a bottom view of the sinker cap of the machine according to FIG. 1.

FIG. 6 shows a detail of a modified embodiment of the machine according to FIG. 1.

FIG. 7 shows a top view of another embodiment of a knitting machine according to the invention.

FIG. 8 shows a longitudinal cross-section of the knitting machine according to FIG. 7.

FIG. 9 shows a detail of a modified embodiment of a knitting machine according to FIGS. 7 and 8.

FIG. 10 shows a part of a third embodiment of a knitting machine according to the invention.

FIG. 11 shows a detail of a fourth embodiment of a knitting machine according to the invention.

FIGS. 12 and 13 show details of the arrangement and orientation of a cam surface.

The circular knitting machine according to FIGS. 1 to 5 comprises a base plate 1, on which is mounted a revolving cylinder 2, the entire cylindrical surface of which is provided with longitudinal slots, in each of which lies a needle 3. Directly below each needle 3 is a jack 4, by means of which the needle can be set at a desired level with the aid of a device 5 before the needle reaches the stitch cam.

Fastened to the top of the needle cylinder 2 are the inner sinker ring 6 and the outer sinker ring 7. In slots of the sinker rings 6 and '7, and between every two needles 3, a sinker 8, 9, 10 or 11 is present. The sinker 10 has a straight underside and a high butt (FIG. 3). The sinkers 10 are distributed alternately with one of the other three types of sinkers over the entire circumference of the sinker rings 6 and 7. Sinkers 8, 9, and 11 are found only in given sectors of the circumference. The sinkers 8 are found over the sector A (FIG. 5), the sinkers 9 are found over the sector B (FIG. 5), and the sinkers 11 are found over the remaining sector of the circumference. If the total number of sinkers is 400, there are thus 200 sinkers 10, about 50 sinkers 8, about 50 sinkers 9, and about sinkers 11. The underside of the sinkers 8, 9 and 11 is partly lowered, and the corresponding slots of the outer sinker ring 7 are made correspondingly deeper. In the lowered underside of the sinker 8 a recess 12 is present, and in the lowered underside of the sinker 9 a recess 13 is present. Fitted over the sinkers is a stationary sinker cap 14, the latter comprising a circular groove 15, through which the sinkers are adapted to move. Above the stitch cam the groove 15 bends outwards and then inwards again, so that the sinkers perform an outward and subsequently an inward movement above the stitch cam. At the point where the groove 15 bends inwards again the sinker cap has been provided with a lip 16, which is adapted to pivot about a pin 17 and can be pushed in by a rod 18 until it reaches a position in which it projects into the groove 15, and can be retracted to a position in which it lies outside the groove 15.

The lip 16 is adapted to move slightly in the vertical direction on the pin 17 and is kept in the lowermost position by a spring 19. Fitted to the underside of the lip 16 is a downwardly directed leaf spring 20, which has its greatest dimension in the circumferential direction and thus springs in the radial direction. The underside of the leaf spring 20 cooperates with a cam surface 21, which is provided on a part of the circumference of the outer sinker ring 7, and of which the upper side is inclined upwards over the part C (FIG. 5) and is horizontal over the part D (FIG. 5). The cam surface 21, by engaging leaf spring 20, is adapted to lift the lip 16 from the lowermost position, shown in full lines in FIG. 1, to the uppermost position, shown in dotted lines in FIG. 1.

The apparatus described above operates as follows:

During the rotation of the cylinder 2 with the inner sinker ring 6, the outer sinker ring 7, the needles 3, and the sinkers 8, 9, and 11 the sinkers move through the groove of the stationary sinker cap 14, and above the stitch cam they are moved outwards and inwards again owing to the shape of the groove 15. When the mechanism for pushing in the rod 18 is inoperative, all the sinkers after the outward movement are forced inwards again by the edge 22 of the groove 15 (see FIG. 5). The mechanism for operating the rod 18 is adjusted in such a way that the rod 18 pushes the lip 16 inwards at a moment when the sinkers 8 move past, i.e. over the sector A of the sinker ring. The lip 16 then enters the recess 12 of the sinkers 8, and as long as sinkers 8 alone (alternately with sinkers 10) move past, the movement of the sinkers is still determined by the edge 22 of the groove 15. When the lip 16 moves inwards, the leaf spring abuts against the side of the cam surface 21 and turns aside, so that the movement of the lip 16 is not stopped.

When the first sinker 9 reaches the lip 16, i.e. as soon as the sector B reaches the lip 16, the sinkers 9 are forced inwards by the lip 16 sooner than normal, through which it is ensured that the yarn comes to rest on the head 24 of the sinker 9 instead of the normal supporting surface 23. The sinkers 10, which alternate with the sinkers 9, have a straight underside, so that they are not acted upon by the lip 16 and the yarn comes to rest normally on the supporting surface 23 on these sinkers. The line joining the points of support of the yarn on two successive sinkers 9 and 10 will thus be inclined, in consequence of which the distance between said line and the head of the needle between the two sinkers 9 and 10 in the lowermost position of the needle movement is greater than normal and a special pattern can be worked for which this is required. This process of the distance in question becoming greater than normal takes place instantaneously and completely when the first sinker 9 reaches the lip 16, so that faulty knitting due to intermediate positions, which would arise with normal control, is avoided. When the sector B moves past, the cam surface 21 ends, so that the leaf spring 20 of the lip 16 springs back into the vertical position.

In the remaining sector of the sinker ring, the sinkers 10 alternate with sinkers 11, which have no recess in the outer side, so that the sinkers 11 are also forced inwards by the lip 16. When the end of the sector in question approaches, the upwardly inclined part C of the cam surface 21 begins, the leaf spring 20 moves up against this part C, and the lip 16 is lifted into the highest position without its action on the sinkers 11 being affected.

When the first sinker 8, i.e. the sector A, approaches the lip 16 again, the latter has been given its highest A} position, and it is kept in this position by the part D of the cam surface 21. In the highest position of the lip 16 the latter engages a portion of the sinkers 8 above the recess 12 thereof, and the sinkers 8 therefore also forced inwards prematurely by the lip 16.

When the last sinker 8 has moved past, the lip 16 is still in the highest position and the first sinker 9 (of the sector B) which approaches the lip 16 falls with the recess 13 over the lip 16, so that the rear of the sinker 9 is forced inwards again by the edge 22 of the groove 15 instead of by the lip 16. The action of the lip 16 therefore also ends instantaneously and completely, so that also at the end of the operation no faulty knitting takes place. The lip 16 is pulled out by the rod 18 before the cam surface 21 ends and before the sector B ends.

It is also possible to make the underside of the sinkers 10 identical with the underside of the sinkers on either side of it, so that all the sinkers are forced inwards, but in that case the head 24 of the sinkers has to be lowered in order to keep the distance between the line joining the points of support of the yarn on two adjacent sinker heads and the head of the needle in the lowermost point of the needle movement at the right value.

According to a variant (FIG. 6) it is possible to provide two lips and 161 one above the other instead of one movable lip 16, so that the cam surface 21 becomes superfiuous, but in this case a separate control rod has to be provided for each of the

lips

160 and 161. The lip 161 then has to move inwards over a sector corresponding with the sector over which the lip 16 is in the lowermost position, while the lip 160 has to move inwards over a sector corresponding with the sector over which the lip 16 is in the uppermost position. In this case the

lips

160 and 161 may be slidably fitted in a block 162 mounted on the sinker cap 14.

For the embodiment according to FIGS. 7 and 8 use has been made of the fact that the needle butts of circular knitting machines in general have different lengths over the various sectors of the cylindrical surface of the needle cylinder. In the slots 31 of the needle cylinder 32 the needles 33 have been inserted in such a way that over a relatively large sector there are needles with short butts 34, over two adjacent relatively short sectors on either side there are needles with long butts 35, and over the remaining relatievly large sector there are needles with medium-sized butts 36. In the lower part of the stitch cam 37 has been made a recess 38, which does not extend the full width of the stitch cam 37. In this recess 38 a cam 39 has been slidably and rotatably fitted. The cam 39 is kept in the outermost position by a spring 40, and the rod 41 to which the cam 39 is fastened is controlled in such a way that the cam 39 can take up two positions, viz. a position in which it lies inside the recess 38 and a position in which it projects a few millimetres beneath the stitch cam 37, while in the projecting position of the cam 39, the latter can moreover be displaced inwards by the rod 41 against the action of the spring 40. A recess 42 has been made at the top of the longest needle butts of the sector following the butts 34 in the circumferential direction. Cam 39 enters recess 42 when rod 41 is biased inward. In the outermost position of the cam 39 the latter is outside the range of the butts 34, but engages the butts 35 and 36.

The apparatus described above operates as follows:

With plain knitting the cam 39 lies retracted into the recess 38 of the stitch cam 37 and is kept in the outermost position by the spring 40. When the control mechanism of the cam 39 is put into operation, the rod 41 is turned so as to move the cam 39 out of the recess, at a moment when the needles with the short butts 34 move past. The cam 39 is outside the range of the short butts 34, so that the normal movement of the needles 33 continues as long as the butts 34 move past the stitch cam.

As soon as the first needle with a long butt 35 reaches the underside of the stitch cam 37, it is engaged by the cam 39 and forced to move downwards further than normal. This applies also to the butts 36 and to the second set of butts 35. As the second set of butts 35 moves past, the rod 41 is forced in by the control mechanism, so that now also the butts 34 are engaged by the cam 39 and also the needles with the short butts 34 move downwards a few millimeters further than normal. When the last butt 34 has moved past, the cam 39 falls into the recess 42 of the first group of needles with long butts 35, so that said needles perform the normal movement along the underside of the stitch cam 37 again, and as said group of needles moves past, the rod 41 is turned so that the cam 39 again comes to rest inside the stitch cam 37, and the pressure on the rod 41 is removed, so that the cam 39 returns to the position of rest. The process of the needles moving downwards further than normal thus takes place accurately over one revolution of the needle cylinder 32 and no faulty intermediate positions are possible.

In the variant according to FIG. 9 two

cams

391 and 392 are present, which have been mounted on the control shaft 411 and on the coaxial control shaft 412 respectively. The shafts 411 and 412 are hollow and are able to'perform a rotary movement under the influence of a control mechanism. However, they cannot be displaced in the radial direction. The

cams

391 and 392 are controlled in such a way that the cam 392 is put into operation first, as the needle butts 34 move past, that the cam 391 is also put into operation as the needle butts 35 move past, that the cam 392 is disengaged first, again as the needle butts 34 move past, and that the cam 391 is disengaged last, as the recesses 42 of the first group of needle butts 35 move past.

The variant according to FIG. 9 requires a double control system, just as the variant according to FIGURE 6. These variants have the advantage that they are suitable not only for knitting patterns in which switching is performed after every revolution, but can also be used if switching after every two or more revolutions adjustment is necessary.

FIG. shows an embodiment in which the needles 53 have an extension 54 with an additional butt 55. In this case the normal butts 56 of the needles move through a normal stitch cam 57, and the landing cam 58 in this embodiment has been modified in such a way that the needle butts 56 have room to move downwards slightly further than normal. To achieve this, the cam 58 may be narrowed according to the dotted line 59, but it is also possible for instance, to fit the cam 58 resiliently or to give it enforced motion.

The additional needle butts 55 of the needles 53 are present over a part of the cylindrical surface of the needle cylinder 52 at such a level that they are able to cooperate with a cam 60, while over the remaining part of the cylindrical surface of the needle cylinder 52 the additional butts lie at a different level and are able to cooperate with a cam 61. The cams 60 and 61 are slidably fitted in a setting device 62, and in the case of plain knitting they are outside the range of the additional butts 55, but when the needles 53 have to be moved downwards further than normal, one of the cams 60 or 61 is first brought in the working position, at a moment when none of the additional needle butts 55 moves past the corresponding cam. When, upon further rotation, the cam in question has become active on the corresponding needle butts 55, the other cam is put into operating position, said cam thus having no needle butts 55 facing it. When, upon further rotation, the second cam acts on the corresponding needle butts, the first cam is retracted, and when the last needle butts have moved past the second cam, the second cam is retracted. Here again therefore the process of the transition from the normal movement of the needles 53 to the special movement, i.e.

deeper than normal, takes place instantaneously and completely, and its termination too takes place instantaneously and completely.

In certain cases it is possible to effect the different movement of the needles 53 with the aid of a stationary additional cam 71 (FIG. 11), fitted between the stitch cam 72 and the landing cam 73, in such a way that the needles which have been brought in the high position before the stitch cam 72 is reached, by a selector device resembling the device 5 of FIG. 1, pass normally along the stitch cam 72, while the needles which have been brought in a lower position before the stitch cam 72 is reached, pass along the cam 71, which ends at a slightly deeper level than the underside of the stitch cam 72. In this case therefore e.g. every other needle performs the normal knitting movement and the intermediate needles move downwards slightly deeper than normal. When all the needles have been brought in the highest position by the selector device before the stitch cam 72 is reached, as is customary with plain knitting, all the needles will perform the normal movement.

What I claim is:

1. A circular knitting machine comprising a rotary cylinder about which are distributed two sets of Working elements in alternating relation, said working elements comprising a set of latch needles each reciprocatable in a longitudinal slot in the outer circumference of said cylinder and a set of sinkers each reciprocatable in a radial slot in the upper end of said cylinder, each of said sinkers having a butt extending in a sinker cam track for radially reciprocating the sinkers, each of said needles having a butt extending in a needle cam track for longitudinally reciprocating the needles, and means insertable into the path of one set of said working elements for modifying the cam track for reciprocating said elements, said insertable means comprising at least one cam insertable into the path of said one set of working elements during slightly more than one full revolution of the rotary cylinder and also displaceable in a direction transverse to its main plane of movement between an inserting position and a withdrawal position overlapping each other, one circumferential group of said one set of working elements only contacting said cam when in withdrawal position, another group of said one set of working elements only contacting said cam when in inserting position and another group of said one set of working elements contacting said cam both when in inserting position and when in withdrawal position, said one set of working elements being divided into circumferential groups having a mutually different location of their portion contacting said insertable means, one circumferential group of said one set of working elements contacting said insertable means in one position of adjustment of said insertable means and another circumferential group of said one set of working elements contacting said insertable means in another position of adjustment of said insertable means.

2. A machine according to claim 1 wherein said insertable means comprising two cams each operating on a different group of said one set of working elements and each alternately insertable into and retractable from the path of the elements of the respective group when said group is in another part of the circumference of the rotary cylinder than said cam track.

3. A circular knitting machine comprising a rotary cylinder about which are distributed two sets of working elements in alternating relation, said working elements comprising a set of needles each reciprocatable in a longitudinal slot in the outer circumference of said cylinder and a set of sinkers each reciprocatable in a radial slot in the upper end of said cylinder, each of said sinkers having a butt cooperating with a sinker cam track for radially reciprocating the sinkers, each of said needles having a butt cooperating with a needle cam track for longitudinally reciprocating the needles, and at least one cam insertable into the path of one set of said working elements for modifying the cam track for reciprocating said elements, said cam being also displaceable in a direction transverse to its main plane of movement, between an inserting position and a withdrawing position, said one set of working elements being divided into three successive circumferential groups having a mutually different location of their portion contacting said cam so that the first circumferential group of said elements only contacts said cam when in Withdrawing position, the second group of said elements only contacts said cam when in inserting position and the third group of said elements contacts said cam both when in inserting position and when in withdrawing position, and means for inserting said cam when said first group of elements is passing by, maintaining said cam in inserting position when said second group of elements is passing by, shifting said cam from inserting to withdrawing position when said third group is passing by, maintaining said cam in withdrawing position when said first group again passes by and withdrawing said cam when said second group again passes by.

4. A circular knitting machine comprising a rotary cylinder about which are distributed two sets of working elements in alternating relation, said Working elements comprising a set of needles each reciprocatable in a longitudinal slot in the outer circumference of said cylinder and a set of sinkers each reciprocatable in a radial slot in the upper end of said cylinder, each of said sinkers having a butt cooperating with a sinker cam track for radially reciprocating the sinkers, each of said needles having a butt cooperating with a needle cam track for longitudinally reciprocating the needles and two cams each insertable into the path of one set of said working elements for modifying the cam track for reciprocating said one set of elements, said one set of working elements comprising two successive circumferential groups having a mutually diiferent location of their cam contacting portion, so that the first circumferential group of said elements only contacts said first cam and the second circumferential group of said elements only contacts said second cam, and means for inserting said second cam when said first group of elements is passing by, maintaining said second cam inserted when said second group of elements is passing by, inserting said first cam when said second group of elements is passing by, withdrawing said second cam when said first group of elements again passes by, maintaining said first cam inserted when said first group of elements again passes by, and withdrawing said first cam when said second group of elements again passes by.

5. A circular knitting machine, according to claim 4, in which said one set of working elements comprises a third circumferential group situated between said second and said first groups, said third group contacting both the first cam and the seond cam in their inserted position, and means for maintaining both the first and the second cam inserted when said third group is passing by.

References Cited by the Examiner UNITED STATES PATENTS 1,831,129 11/31 Minton et a1 6654X 2,075,077 3/37 Aaronson 66-54 X 2,208,307 7/40 Lawson et al 6654 2,421,816 6/47 Thurston et al. 6693 2,981,085 4/61 Mahler et al 66--54 3,007,325 11/61 Smith 66-54X 3,052,109 9/62 Hanel 66-95 DONALD W. PARKER, Primary Examiner.

RUSSELL C. MADER, Examiner.

Claims

1. A CIRCULAR KNITTING MACHINE COMPRISING A ROTARY CYLINDER ABOUT WHICH ARE DISTRIBUTED TWO SETS OF WORKING ELEMENTS IN ALTERNATING RELATION, SAID WORKING ELEMENTS COMPRISING A SET OF LATCH NEEDLES EACH RECIPROCATABLE IN A LONGITUDINAL SLOT IN THE OUTER CIRCUMFERENCE OF SAID CYLINDER AND A SET OF SINKERS EACH RECIPROCATABLE IN A RADIAL SLOT IN THE UPPER END OF SAID CYLINDER, EACH OF SAID SINKERS HAVING A BUTT EXTENDING IN A SINKER CAM TRACK FOR RADIALLY RECIPROCATING THE SINKERS, EACH OF SAID NEEDLES HAVING A BUTT EXTENDING IN A NEEDLE CAM TRACK FOR LONGITUDINALLY RECIPROCATING THE NEEDLES, AND MEANS INSERTABLE INTO THE PATH OF ONE SET OF SAID WORKING ELEMENTS FOR MODIFYING THE CAM TRACK FOR RECIPROCATING SAID ELEMENTS, SAID INSERTABLE MEANS COMPRISING AT LEAST ONE CAM INSERTABLE INTO THE PATH OF SAID ONE SET OF WORKING ELEMENTS DURING SLIGHTLY MORE THAN ONE FULL REVOLUTION OF THE ROTARY CYLINDER AND ALSO DISPLACEABLE IN A DIRECTION TRANSVERSE TO ITS MAIN PLANE OF MOVEMENT BETWEEN AN INSERTING POSITION AND A WITHDRAWAL POSITION OVERLAPPING EACH OTHER ONE CIRCUMFERENTIAL GROUP OF SAID ONE SET OF WORKING ELEMENTS ONLY CONTACTING SAID CAM WHEN IN WITHDRAWAL POSITION, ANOTHER GROUP OF SAID ONE SET OF WORKING ELEMENTS ONLY CONTACTING SAID CAM WHEN IN INSERTING POSITION AND ANOTHER GROUP OF SAID ONE SET OF WORKING ELEMENTS CONTACTING SAID CAM BOTH WHEN IN INSERTING POSITION AND WHEN IN WITHDRAWAL POSITION, SAID ONE SET OF WORKING ELEMENTS BEING DIVIDED INTO CIRCUMFERENTIAL GROUPS HAVING A MUTUALLY DIFFERENT LOCATION OF THEIR PORTIOM CONTACTING SAID INSERTABLE MEANS, ONE CIRCUMFERENTIAL GROUP OF SAID ONE SET WORKING ELEMENTS CONTACTING SAID INSERTABLE MEANS IN ONE POSITION OF ADJUSTMENT OF SAID INSERTABLE MEANS AND ANOTHER CIRCUMFERENTIAL GROUP OF SAID ONE SET OF WORKING ELEMENTS CONTACTING SAID INSERTABLE MEANS IN ANOTHER POSITION OF ADJUSTMENT OF SAID INSERTABLE MEANS.