EP1894494A1 - Spring system for mattresses - Google Patents

Abstract

The supporting plate grid (1) has a transfer device arranged between adjacent supporting plate holders. The transfer device has a pendulum (12), which is supported by a swivel pin (13) on a longitudinal bar (14) of the supporting plate grid and is suspended at a two-armed supporting plate carrier (8) by a suspension pin (11), where supporting plate carrier holds the supporting plate holder.

Description

Subject of the invention

The invention relates to a slatted frame for receiving mattresses with the mattress supporting, extending transversely to the longitudinal direction of the slatted base slats, which are housed in two-armed, resilient support battens, which are mounted on a longitudinal spar of the slatted frame, wherein between adjacent slat holders each have a transmission device is provided which transmits this movement in the sense of lifting or stiffening on at least one adjacent support bar holder when loading a support bar and lowering its support bar holder.

It may be essentially resilient battens on which a mattress is usually placed directly or rigid support slats on which spring elements are fixed, on which the mattress is placed.

State of the art

The DE 20 2004 011 233 U1 refers to a slatted base, which has retaining caps for paired battens for receiving mattresses. The retaining caps have two each laterally downwardly spread, resilient support members which are attached to stationary fittings on the longitudinal spar of the slatted frame. Among these fittings rocker elements are pivotally mounted on bolts, which engage with lateral arms under a respective support member adjacent retaining caps. When loading a pair of battens, the support members spring down and load one side of the voltage applied to them rocker elements. By pivoting the rocker elements, this movement is transmitted to the support members adjacent retaining caps and increase their support effect. By the rocker elements so a compression of a retaining flap is transmitted as rebounding on adjacent retaining caps.

Also in the DE 20 2005 013 019 U1 are supporting elements for mattresses or mattresses superimposed, resilient battens revealed, which also spreads obliquely downwards Have struts. They slide in horizontal guides, in which between the ends of the struts each a spring-damper element is slidably mounted. In a straddle the struts of a loaded support element, the spring legs of the adjacent support elements are erected by the spring-damper elements and transmit the deflection of a support element as pushing up or stiffening on adjacent support elements.

The DE 20 2005 013 018 U1 shows a spring base, wherein the obliquely downward and outwardly extending struts supported by support plate or support slats supporting support members on stationary bolts and are connected above these bolts by a coupling element. When loading a support element, its struts are pressed down and pull on the coupling elements, the struts of adjacent support elements upwards.

The DE 200 00 477 U1 discloses a coupled waveband suspension for bed underframes and mattresses, in which crosswise longitudinally and transversely arranged waveband springs bear on their maxima support elements and in their abutment-representing minima are supported by sliding or roller bearings.

All these devices are characterized in that a compression of a support element is transmitted as a supporting effect on adjacent support members. In this case, this transferring the supporting effect is provided both between arranged on battens single spring elements for carrying a mattress as well as between resilient or rigid and provided with individual spring elements battens for a mattress or even in a mattress itself.

The obliquely downwardly expanding spring struts of the support elements of the first three publications are arranged on the support elements, with these in one piece and extend to the support bolt or to stationary guides. A support element accordingly extends from support bolts to support bolts or from guide to guide. The support arms of the support elements are mounted stationary, the transfer of the support effect is carried out by separate transfer bracket.

General description of the invention

The object of the invention was made to improve the storage of battens in a sub-bed, wherein the transfer effect of a resilient lowering of a support bar should be maintained and improved as resilient lifting on adjacent battens.

It solves this problem in that the supporting slats supporting the support slats are fastened by means of supporting bolts at the lower ends of pendulums, which in turn can swing around bearing pins in the longitudinal beams of the slatted bases. In this case, the batten support may extend from support bar holder to support bar holder and be mounted in the middle of the pendulums, but they can also extend from support bolts to support bolts and store in their midst on support bolts to a support bar holder. The transmission device is formed here by the pendulum suspension of the support slats and their coupling via the support bolts. Elasticity and spring action is given in rigid slats except by arranged on them spring elements by the flexible arms of the slatted support and resilient support slats in addition to the spring action.

The juxtaposition of individual battens is selected solely for manufacturing reasons. In itself, the truss beams could be integrally continuous. However, since they are usually made by injection molding from plastic, this would require a very large and expensive mold.

In order to improve the mobility of the pendulum and thus the transmission of compression and rebound, in an embodiment of the invention, the bearing pin of the pendulum in the longitudinal members in slotted holes can be freely displaced. It is particularly advantageous if these slots are designed as against their ends upwardly curved scenes.

If it seems desirable to transfer the transmission of the deflection of a slat holder only reduced to an adjacent support bar holder, the amplitude of the pendulum can be limited. This can be done by pins which are arranged stationarily approximately at the longitudinal spar of the sub-bed and engage in recesses of different width in the pendulum. In other cases, the pendulum of the pendulum can be limited by scenes that are pivotable about the pendulum.

In addition, the resilient support members provide the possibility of partially reducing or stiffening the resilience or spring effect of the underbed.

For this purpose, it is provided to insert wedges in the gap between the support plate carriers and the support slats supported by them, which impede a narrowing of this column and thus limit the compression of the support slat support, so they stiffen. In this case, the wedges or the surfaces to which they invest, be stepped and cause a stiffened stiffening of the device.

In a further embodiment, the gaps have noses in front of which locking slides can be displaced, which prevent narrowing of the gaps and thus likewise cause stiffening of the support slat bearers. The noses of the column or - in kinematic reversal - the locking slide can have different heights and thus determine the degree of stiffening of the support slats.

The wedges and cams must be kept in their intended position even with changing load. A suitable measure consists in nubs with their associated notches on the lath supports and the lath holders, which can engage in the intended positions.

A triangular or a 180 ° rotated T-shaped pendulum, which is articulated at the top of the longitudinal spar and at the ends of its base each support an arm of a slat holder offers the advantage that spreading the arms of a slat holder with increasing load stronger effect on the lifting of the adjacent slat holder.

Specific description of the invention

• Fig. 1 ein erstes Ausführungsbeispiel im Längsschnitt und im Blick auf den Längsholm des Unterbettes mit von Traglatte zu Traglatte durchgehenden Traglattenträgern;
• Fig. 2 eine perspektivische Ansicht des Gegenstandes der Fig. 1;
• Fig. 3 ein zweites Ausführungsbeispiel mit von Bolzen zu Bolzen durchgehenden Traglattenträgern in Darstellung wie in Fig. 1 jedoch ohne Traglatten;
• Fig. 4 eine perspektivische Ansicht des Gegenstandes der Fig. 3;
• Fig. 5 eine Ausführungsform mit in Langlöchern geführten Lagerbolzen der Pendel;
• Fig. 6 eine Variante der Ausführungsform der Fig. 5 mit in gewölbten Langlöchern;
• Fig. 7 eine Ausführungsform ähnlich der Fig. 1 mit Aufnahmen für federnde Traglatten;
• Fig. 8 eine perspektivische Ansicht des Gegenstandes der Fig. 7;
• Fig. 9 eine erste Vorrichtung zum Begrenzen der Pendelbarkeit der Pendel;
• Fig. 10 eine zweite Vorrichtung zum Begrenzen der Pendelbarkeit der Pendel;
• Fig. 11 eine weitere Vorrichtung zum Begrenzen der Pendelbarkeit der Pendel;
• Fig. 12 eine andersartige Einrichtung zum Begrenzen der Nachgiebigkeit der Traglattenträger mittels parallel zu ihnen einschiebbaren Keilen in Stirnansicht;
• Fig. 13 bis 15 unterschiedliche Einschubtiefe der Keile;
• Fig. 16 ein Keil in Seitenansicht;
• Fig. 17 bis 19 eine weitere Einrichtung zum Begrenzen der Nachgiebigkeit der Traglattenträger mittels senkrecht zu ihnen einschiebbaren Keilen in drei Stufen in perspektivischer Ansicht;
• Fig. 20 die Draufsicht auf einen Keil der Fig. 17 bis 19;
• Fig. 21 die Stirnansicht eines Traglattenträgers nach den Fig. 17 bis 19;
• Fig. 22 sie perspektivische Ansicht einer weiteren Ausführungsform zum Begrenzen des Durchfederns der Traglattenträger;
• Fig. 23 eine Variante der Ausführungsform der Fig. 22;
• Fig. 24 eine Variante der Ausführungsform der Fig. 4 mit 2 Tragbolzen am Pendel zur Aufnahme der Arme von Traglattenträgern.

In the figures of the drawing embodiments of the invention are shown. Show it

• Fig. 1 shows a first embodiment in longitudinal section and in view of the longitudinal spar of the lower bed with continuous from support bar to batten battens;
• Fig. 2 is a perspective view of the article of Fig. 1;
• Fig. 3 shows a second embodiment with bolt-to-bolt support struts in illustration as shown in Figure 1, but without battens.
• Fig. 4 is a perspective view of the article of Fig. 3;
• 5 shows an embodiment with guided in oblong holes bearing pin of the pendulum;
• 6 shows a variant of the embodiment of Figure 5 with curved slots.
• Fig. 7 shows an embodiment similar to Figure 1 with receptacles for resilient battens.
• Fig. 8 is a perspective view of the article of Fig. 7;
• 9 shows a first device for limiting the pendulum mobility of pendulums;
• 10 shows a second device for limiting the pendulum mobility of pendulums;
• 11 shows another device for limiting the pendulum mobility of pendulums;
• 12 shows a different type of device for limiting the compliance of the support slat carrier by means of parallel to them retractable wedges in front view;
• Fig. 13 to 15 different insertion depth of the wedges;
• Fig. 16 is a wedge in side view;
• FIGS. 17 to 19 show a further device for limiting the compliance of the carrier slats by means of wedges which can be inserted perpendicular to them in three stages in a perspective view;
• Fig. 20 is a plan view of a wedge of Figs. 17-19;
• FIG. 21 shows the front view of a support plate carrier according to FIGS. 17 to 19; FIG.
• Fig. 22 is a perspective view of another embodiment for limiting the deflection of the slat supports;
• FIG. 23 shows a variant of the embodiment of FIG. 22; FIG.
• Fig. 24 shows a variant of the embodiment of Fig. 4 with 2 support pins on the pendulum for receiving the arms of support struts.

Figures 1 to 8 show a section of a slatted base 1 with only indicated in Figure 1, resting mattress 2 in section along the bed.

In the embodiments of Figures 1 to 6, the support slats 3 of the slatted base 1 on a plurality of surface arranged spring elements 4, of which only one is shown on each support bar here. The spring plate 5 sitting on elastic arms 6, which emanate from holders 7, by means of which they are angeklippst example, on the support slats 3. In the illustration, two spring plates 5 are fastened to a holder 7, but it is understood that the spring elements 4 can also be attached individually, to three, to four, etc. to a holder.

The ends of the battens 3 sit in battens holders 9, of which battens support 8 with preferably flexible arms 10 go out. In the embodiment of FIGS. 1, 2 and 5 to 8, the slat supports extend from one slat holder to the adjacent slat holder and have a bearing bush in the middle of their arms. By contrast, in the embodiment of FIGS. 3 and 4, the carrier carriers extend from the bearing bush on one arm 10 via the carrier bar holder 9 to the bearing bush on its other arm 10.

The bearing bushes of the arms 10 are rotatable and pivotable on support pins 11, which sit at the lower ends of pendulums 12, which in turn are hinged to pivot pins 13 which are fixed in the longitudinal spar 14 of the slatted base 1. The arms 10 of each supporting strip carrier 8 extend obliquely from one of the supporting pins 11 upwards to one of the supporting strip holders 9.

When the mattress 2 is approximately uniformly loaded surface, give the arms 6 of the spring elements 4 with the spring plates 5 and cause the elasticity of the support of the mattress. When the load concentrates on one or more spring elements of a support bar 3 (arrow a), it deviates downward (arrow b), the two outgoing from her battens 8 under elastic deformation of their arms 10, the two adjacent pendulum 12 deflect (arrows c) pushing the two adjacent battens 3 'and 3 "upwards (arrows d), so that the compression of one bat is transferred to the two adjacent battens as rebounding (arrows e) retroactively stiffening the support of the output slat.

This transfer of compression of a slat in a rebound of an adjacent slat takes place analogously in the embodiment of Figure 3/4.

The mutual support of battens 3 by acting in the form of a transfer device, pendulum suspended support slat 8 is given over the entire length of the slatted base 1. However, it takes place mainly in the shoulder area or in the area of the buttocks. Thus, with a heavier load on a slat under the shoulder area or the buttocks, the adjacent slats below the head or the lumbar area are more strongly supported. At the end of a region provided with the transmission device or at the ends of the slatted base slatted support 8 as not shown in detail can be supported on one side on a fixed abutment.

As can be seen from the perspective views, the fastening points of the support slat support 8 to the support slat holder 9 and the support arms 10 are alternately narrowed to the support pin 11 so that they find each other on this place.

If the pivot pin 13 of the pendulum 12, as shown in Figure 5, are slidably guided in a slot 15, they can move laterally in a straddle of a resilient pad carrier 8 and thus facilitate the transfer of the compression effect as a Ausfederungswirkung on the adjacent battens and on the These supported battens 3. The rebound effect on adjacent battens can thereby be further increased if the pivot pin 13 of the pendulum 12 as shown in Figure 6, are guided in a laterally concave upwardly curved slot 16. In a straddle the batten support 8, the pivot pin 13 laterally into a higher lying region of the elongated hole 16 shifted and leave so feathering a neighboring slat support higher.

While the embodiments described above are based on rigid battens 3, which as a rule should be provided with spring elements 4 for a flexible support of the mattress 2, FIGS. 7/8 show an embodiment in which the battens 8 'are designed to accommodate resilient support arms 17 are each set up with a support bar holder 9 'for resilient, not shown here slats. The support arms can also be made mehrgliedrig, so have several, splitting and rejoining arms.

The support slats 8 'extend here as in the figures 1/2 and 5/6 of support bar holder 9' to support bar holder 9 '. These are therefore designed so that two support slat holder shots of two adjacent slat support 8 'together can support a support slat holder 9'. It is understood that even in the embodiment of Figures 7 and 8, the support slat support 8 'as from support pin 11 to support pin 11 may be formed continuously.

If the deflection of a supporting bar 3 is to be transmitted only to a reduced extent as rebounding on adjacent battens in order to avoid rocking movements along the lower bed, damping devices as shown in FIGS. 9 to 23 can be used.

In the embodiment of Figure 9 is laterally adjacent to the pivot pin 13 of a pendulum 12 _2, a link 19 pivotally mounted about a fixed to the longitudinal spar 14 of the bed 1 pin 20. The scenery can be pivoted about the pendulum 12 ₂ and limits - as long as it is not pivoted - its pivotal movement, in a first, pulled-out position shown low and in a second, dashed line position more or less. The pivoting position of the gate 19 can be determined and secured by grooves 21, 22 in the pendulum, the first, upper groove 21 can allow clearance between gate and groove.

In the embodiment of Figure 10, the pendulum 12 ₃ below its pivot pin 13, a recess 23 which is penetrated by a toggle 24. The toggle is rotatable about a stationary pin 25 in the longitudinal spar 14 of the lower bed 1. When pulled out horizontally position of the knob pivotal movement of the pendulum is prevented in dashed vertical position is not limited.

In Figure 11, an embodiment is shown, in the pendulum 12 _{4 a} plurality of holes 26, 28 are arranged, through which a retaining pin 27 is inserted into a lying behind the pendulum bore in the longitudinal spar. Depending on which of the holes of the retaining bolt is inserted, the pivoting of the pendulum is more or less prevented.

Even if the pivotability of a pendulum 12 ₂ , 12 ₃ or 12 ₄ is limited or completely prevented by the described devices, a muted transfer of a pivoting movement from a support bar holder 8 to an adjacent one can be retained insofar as the pendulum can be resilient in itself as indicated by its slimming in its middle region.

Other ways to change the stiffness of the storage of the mattress, provide to reduce the spring action of the support slats 8, thus increasing their rigidity and reduce their compliance.

Two alternative embodiments shown in FIGS. 12 to 16 and 17 to 21 consist of two gaps 29 and 30, respectively, extending from a pendulum 12 via a support strut holder 9 to an adjacent pendulum, between a support strut holder 9 and the associated strut support 8. 31 and 32 to provide such that they narrow when springing the Traglattenträger. In this two column two locking members 33 and 34 can be inserted, which narrow the column and thus hinder the ability of the slat support to spring through and stiffen it.

In the embodiment according to FIGS. 12 to 15, the two gaps 29 and 30 lie opposite one another in a plane. The locking member 33 has two fork-shaped tongues 35 which can be pushed parallel to the support bar in the column. Its two tongues are connected by a retaining support plate 36. The support bar holder 9 can on its underside inclined support surfaces 37 and the support plate carrier 8 may have this support surface opposing cams 38. In this case, the tongues 35 are advantageously adapted to the slope of the support surfaces 37.

• Figur 13 ohne Sperrglied 33: keine Versteifung,
• Figur 14 niedere Stufen 39 der Zungen 35: geringe Versteifung,
• Figur 15 hohe Stufen 40 der Zungen 35: starke Versteifung.

The fork-like tongues 35 of the locking member have at least one, as shown in FIG 16 two stages 39, 40, whose effectiveness is determined by the depth of their insertion into the column. The engagement of the locking member 33 in the column 29/30 can thus be stepped, so that the stiffening of the spring action are adapted to different requirements can. Depending on the insertion depth, three stages of stiffening the spring action can be achieved with a stepped wedge approximately according to FIG. 16:

• FIG. 13 without blocking member 33: no stiffening,
• FIG. 14 lower steps 39 of the tongues 35: low stiffening,
• Figure 15 high levels 40 of the tongues 35: strong stiffening.

By nubs 41 on the tongues 35 or in the columns 29 and 30, which engage in grooves in the respective opposing columns or on the tongues, the locking member 33 is secured in the columns 29,30.

In a further embodiment according to FIGS. 17 and 21, the two gaps 31, 32 are parallel to one another and perpendicular. The locking member 34 here has two by a bridge 42 inverted U-shaped legs 43, which engage in the column from above.

The legs 43 each have two cams 44 which are displaced by moving the locking member 34 on the Traglattenaufnehmer 9 before no or one of two cams 45, 46 in each of the column. Analogously to FIGS. 13 to 15, according to FIGS. 17 to 19, three different stiffening stages can be achieved.

The securing of the locking member 34 in the columns here consists of rails 47 on Traglattenaufnehmer 9, which are overlapped by the legs 43 of the locking member 34. By webs 48 at the edges of the Traglattenaufnehmers 9 slipping out of the locking member 34 in the direction of the slat from the columns 31, 32 is prevented.

FIGS. 22 and 23 show an embodiment in two variants, by means of which the spring travel of the carrier carrier 8 or of the carrier carrier 9 can be limited in a stepped manner.

In the embodiment of FIG. 22, a plurality of, in the illustration, three bores 49 ₁ , 49 ₂ , 49 _{3 are introduced} into the longitudinal spar 14 vertically below the support bar holder 9. In these holes pins 50 may be inserted with possibly different, the longitudinal spar to the interior of the lower bed überragendem outside diameter. become. On these pins, the undersides of the support bar holder 9 and can not continue to spring through. Depending on the hole in which a pin is inserted or which diameter a pin, the springing of the support strut holder can also be limited stepped.

In the embodiment of FIG. 23, only one bore 49 is provided in the longitudinal spar 14. As shown in the two right slat holders 9, an attenuator 51 can be plugged into the bore 49 or on a pin 50 inserted into the bore, which has at least one, eccentrically arranged elastic pad 52. As shown, two opposing pads 52, 53 of different compliance may be attached to the attenuator.

The pads 52, 53 may be made of different resilient foam or as shown in cylindrical or ellipsoidal tubular body made of elastic plastic of different thickness or stiffness. On the second support bar holder 9 from the right is the cushion 52 made of thinner plastic between the support bar holder and the pin, the right support bar holder, the cushion of thicker plastic.

By inserting no pin, a pin 50 with different diameters or an attenuator with one or two elastic pad 52, the spring travel and the resistance to fatigue can be chosen arbitrarily within wide limits.

In many cases, it is advantageous to form the pendulum 12 ₅ as a triangle or rotated by 180 ° T, which is pivotally mounted at its tip in a longitudinal spar 14 and at each end point of its base one arm of a support bar holder 8 rotatably supports.

In this device, when the arms 10 of a stringer support 8 spread more strongly with increasing load and deflect their long bolts 11, the deflection of the pendulum 12 ₅ caused thereby advantageously leads to a clearer increase of the other bolt 11 supporting the adjacent support strut holder 9 at the base of the Pendulum and thus to a greater lifting of this adjacent battens carrier.

It is understood that the transmission devices shown here on one of the two longitudinal beams 14 of a lower bed 1 are also arranged according to the opposite longitudinal beam, so that the support slats 3, 3 ', 3 "are supported equally balancing at both ends.

LIST OF REFERENCE NUMBERS

1

Supporting slats

2

mattress

3,

3 ', 3 "batten

4

spring element

5

spring plate

6

Arm of a spring plate

7

Holder of a spring plate

8, 8 '

Batten support

9, 9 '

Support lath holder

10

Arms of the slatted support 8

11

11 'slat support 8 bearing bolt

12

Pendulum (with indexes)

13

pivot pin

14

longeron

15

straight slot

16

Convex arched slot

17

resilient support arm

18

Foot piece of a support arm 17

19

scenery

20

Cones, the scenery 19

21

upper groove in the pendulum 12 '

22

lower groove in the pendulum 12 '

23

Recess in the pendulum 12 "

24

Toggle in recess 23

25

Thong of the gag 24

26

drilling

27

retaining pins

28

Long hole

29, 30, 31, 32

column

33, 34

locking member

35

Tongues of the locking member 33rd

36

Retaining plate of the locking member 33rd

37

Support surfaces on the support bar holder 9

38

cam

39, 40

Stages of tongues 35

41

burl

42

Bridge of the locking member 34th

43

Leg of the locking member 34th

44

Cam on the legs 43

45, 46

Cam on the support plate carrier 8

47

Rails on the slat carrier 8

48

Stege

49 ₁ , 49 ₂ , 49 ₃

drilling

50

pen

51

attenuator

52, 53

elastic pillow

Claims (10)

A slatted base for receiving mattresses with the mattress supporting, extending transversely to the longitudinal direction of the slatted base slats, which are stored in Traglattenhaltern bearing on a longitudinal spar of the Träglattenrostes, wherein between adjacent Traglattenhaltern a transmission device is provided, the loading of a slat and lowering her Traglattenhalters this movement in the sense of raising or stiffening on at least one adjacent support bar holder transmits, characterized in that the transmission device pendulum (12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ) comprises, on a pivot pin (13) on the longitudinal spar (14) of the slatted base (1) and to which by means of supporting bolts (11) two-armed support slats (8, 8 ') are attached, which support the support slats. A slatted base according to claim 1, characterized in that each slat support (8) is connected to the pendulum (12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ) via a support bolt (11) arranged centrally on it and extends in each case to two adjacent battens (9, 9 ') extends. A slatted base according to claim 1, characterized in that each slatted support (8) is connected to a pendulum (12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ) via a respective support bolt (11) arranged at the ends of its arms (10) is and a centrally arranged on him support bar holder (9, 9 ') carries. A slatted base according to claim 3, characterized in that the pendulum (12 ₅ ) is formed as a triangle which is mounted at its tip oscillating in the longitudinal spar (14) and at each end point of its base with one arm (10) of a support plate carrier (8). is rotatably connected. Slatted base according to one of the preceding claims, characterized in that the pendulum-bearing pivot pin (13) in a horizontal slot (15) or in a slot (16) which is formed from its center of both ends curved upward, in the longitudinal spar (14 ) is guided relocatable. Support slat according to claim 1, characterized in that the transmission device has a pivotability of the pendulum (12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ) limiting device (19 to 22, 23 to 25, 26 to 28). A slatted base according to claim 1, characterized in that a device (29/30, 33, 37, 38; 31/32, 34, 42 to 48, 49 to 51) is provided on each slat support (8), by means of which the deflection of a Traglattenträgers can be reduced under load. A slatted base according to claim 7 comprising two slats (29, 30, 31, 32) formed by a pendulum via a slat holder to an adjacent pendulum supporting slat holders (9) and the associated slatted support (8), in the locking members (33, 34) can be introduced are that narrow the gaps and stiffen the spring action of the support bar holder. A slatted base according to claim 8, characterized in that a locking member (33) or the columns (29, 30) have steps (39, 40) and allow the column to be narrowed in a stepped manner. A slatted base according to claim 8, characterized in that the columns (31, 32) and a locking member (34) cams (44; 45, 46), which allow by the displacement of the locking member to narrow the column graded.

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