CA1138177A - Clasping device with a yoke tightened by a conical screw - Google Patents

Abstract

ABSTRACT
The invention relates to a clamping device for releas-ably connecting objects to each other, e.g. a signboard to a pole, wherein the mounting and dismounting thereof is facilitated. A
yoke (13) is drawn against the holder (11) by means of a tapered screw (15). The screw thread (37) engages the edge (39) of an aperture in the holder so that on rotation the screw is dis-placeable transversely of the yoke. A deformable end portion of the yoke is laid in a loop (33, 57) around the screw (15).

Description

1~l3~7~7 The invention relates to a clamping device including a holder and a yoke meant to be applied from opposite sides against and around an object of some kind, e.g. a rod, so as to be releasably attached thereto.
In a known design of a similar clamping device, one end of the yoke is pivotted to the holder, and the other end of the yoke is drawn towards the holder by means of a detachable nut-and-bolt unit. In another known design the end of the yoke is shaped as a threaded bolt extending through a bore in the holder and the yoke is tightened by a nut on the bolt.
Such known devices are cumbersome to assemble and dis-assemble, the nuts as a rule having to be turned many more revolutions than are required merely for the forceful application of the yoke or for the loosening of its grip. When used outdoors the nuts are apt to stick due to rust and they are also delicate to handle and difficult to be correctly threaded on.
An object of the invention is to provide a clamping device wherein these drawbacks are avoided or minimized, and which i5 easy to apply and to remove and also comprises a minimum of details.
According to the present invention there is provided a clamping device comprising a holder and a yoke for embracing an object and a screw engaging the holder yoke for moving the yoke relative to the holder so as to clamp the object between the yoke and holder, characterized in that the screw is tapered and has a helical thread in threaded engagement with the holder, the screw . ...

1~3817~ 7 extends across the yoke and a portion of the yoke extends around the screw with a face of the yoke in contact with a part of the periphery of the screw such that rotation of the screw relative to the holder advances the screw across said portion of the yoke so as to displace the yoke relative to the holder.
The invention will be described further, by way of example, with reference to the accompanying drawings, in which:-Figure 1 is a perspective view of a first embodiment ofthe device disassembled;
Figure 2 is a perspective view of the first embodiment partly assembled;
Figure 3 is an enlarged cross-section taken along the line III-III in Figure 2;
Figure 4 is an enlarged cross-section taken along the line IV-IV in Figure 3;
Figures 5 and 6 respectively illustrate second and third embodiments of the invention; and Figures 7 and 8 are side and plan views, respectively of a fourth embodiment of the invention.
2Q A clamping device is shown in Figures 1 to 4 comprising three elements, namely a holder (support or base member) 11, a yoke (hasp or strap) 13 and a tapered screw 15. The clamping device is intended to embrace and be tightened around .

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any suitable stationary object~ which is exemplified in Fig. 2 by a rod 17. To the holder 11 there may be attached any appliance or device (not shown) that is desired to be carried by or connected to the rod 17 in a detachable manner.
me holder 11 comprises a plate, preferably of steel, which on opposite sides of an inw ædly curved approximately half-circular edge 19 has two projecting arms or branches 21, 23. me edge of the plate is of such a contour as to fit over ne æ ly half of the circumference of the rod 17. The outer edge of the branch 21 has notches 25 and the yoke 13 is engageable therein once the end of the branch 21 has been passed through longitudinal slot 27 in yoke 13. A circular aperture 29 is provided in the opposite branch of the holder plate and a step 31 and an adjaoent notch 32 æ e provided close to the aperture 29 and in the outer edge of the branch 23.
me yoke 13 comprises a flexible but h ædly stretchable strip~ e.g. of thin sheet steel~ the middle section of which is æched so as to approximately fit with its broad face against c" r.~ e,~
the cylindrical ~;cu~};xrn~e~ of the rod 17 opposite to the edge 19 of the holder 11. When the slot 27 has been hooked into that one of the notches 25 which is best adapted to the size of the rod, one end of the yoke 13 is thus pivotally connected to the holder branch 21 and can be swung down over the rod 17 to embrace the same. At its other end, the tightening end, the yoke 13 is curved outwardly, i.e. oppositely to its middle section, to thus form a bend 33 having a central approximately p æ t-cylindrical portion which merges on both sides into substantially straight portions usually forming an angle of 1~3817i!7 90 to 150 degrees to each other. Along the centre line of said bend there extends a slot 35 of a sufficient length to allow a tongue or prosection 34 of the branch 23 and the greater part of the aperture 29, to pass therethrough (see Fig. 2) until the outer end of the slot 35 is engaged by the step 31 and retained in the notch 32.
For tightening of the yoke the screw 15 is inserted into the aperture 29. m e screw is tapered and in its tapering face there is cut a helical groove 37 forming a thread of such a contour as to make possible a forcible and secure engagement with bevelled edge 39 of the aperture 29. A typical screw has a length of 60 mm, a nE~c mwm diameter of 30 mm and a minimum diameter of 10 mm, but of course, said measures and relations are not critical. In its big end the screw has a hexagonal re oe ss 41 for a correspondingly shaped key, or alternatively, has a diametrically extending groove for a screw driver or a hexagonal head for turning by a wrench. To begin with, the screw can usually be passed partly into the aperture 29 without being turned. When contact is made with the edge 39 as well as with the yoke bend 33, turning of the screw is required for further axial displaoement of the screw. During this turning motion the bend is gradually displaced (dcwnw ædly in Figs. 3 and 4) and widened, so that the outw æ dly cancave portion of the yoke grows, i.e. its end depression is deepened. The ends of the yoke being hooked up on the notches 25, 32 in the holder branches at a fixed mutual distan oe and the yoke not being extensible, the above-& scribed contracting depression at one end of the yoke 1~l3Bl~t7 will cause a corresponding straightening of the yoke in other places, which means that the yoke is being stretched and applied with an increasing force against the rod 17. The contact of the screw with the yoke bend on opposite sides of the aperture 29 has a balancing and stabilizing effect upon the screw, whereby its axial motion is guided in a direction nearly parallel to the trans~erse direction of the yoke or the S f r~ q axial direction of the rod 17. The s~etchin6 of the yoke around the rod 17 corresponds to the increased length of the bend 33 and the adjoining straight portions, and said length grows faster than the growth of the diameter of the screw at the thread engagement point. ~his is because not only the curved portion of the bend 33 but also the two adjoining straight portions grow in length at the same time. ~he yoke slides against the screw but is slightly entrained thereby.
When the screw has been turned enough to give the desired pressure of the yoke against the rod, the screw is self-locking due to the friction and the low pitch of the helical thread; this is true also when the screw is fully circular in all cross-sections. Howe~er, in order to safely prevent unwinding, e.g. due to vibration, it is preferable to make the screw of an~led or cornered section, e.g. octagonal, as shown in Figs. 3 and 4. As an alternative thereto, the screw may shaped with longitudinal furrows and ridges, so that the mainly conical face is dotted with knurls or teeth.
~he term "yoke" used in this description and in the claims is meant to comprise hasps, straps and/or other preferably elongate retaining members, which all have the quality of being 1~3~317 bendable, at least in parts.
Fig. 5 shows a modified embodiment, in which the yoke 13 of Figs. 1 to 4 is replaced by an endless wire loop 43, which is laid into notches in the branches 21, 23 of the holder, and the two parallel strands of whichloop are both stretched by the screw 15 acting against a bight thereof. In this case the wire may encircle more than half the circumference of the rod 17 and the branches 21, 23 be correspondingly shortened.
Fig. 6 shows a further embodiment of the clasping or clamping device suitable for embracing a cornered object, which in the example is a square-sectioned tube 45. ~s the yoke is not easily moved past the protruding corner, it is instead stretched in opposite directions from the middle by ~e .~ ~Q
two oonioal screws 15~ 16 in a symmetrical arrangement.
In the embodiment shown in Figs. 7 and 8, where the ~las-ping-~r clamping device is used for attaching a signboard 47 to a tubular post 49, the holder is doubled in comparison to the above-described design thereof. ~he holder comprises two similar, parallel plates 51, 53 held spaced apart by a vertical plate 55 integral therewith. me yoke or stretching strap 57 extends between said plates and has its ends secured to opposite edges of the plates by means of lateral projections interlocking with correspon~;ng recesses or notches 59, 61 in the two plates.
~he screw 15, which has a uniform pitch, extends through and is guided by apertures 63, 65 situated approximately opposite each other, but, in preferred manner, somewhat offset so that the screw gets enough inclination to have it make contact with the curved face of the strap 57 along a line approximately perpendicular to the plates 51, 53.

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Of course, the above-described embodiments may be modified in several respects without departing from the scope of the invention as set forth by the following claims. ~or instance, one end of the yoke or strap may be permanently connected to the holder, such as by means of a hinge or by forming an integra part of the holder.
~he clasping or clamping device according to the invention has the advantage of easy assemblage and dissemblage. ~ue to the engagement of the screw thread being concentrated to p æ t only of one thread, there is no or only min;m~l risk of a corrosive fixation, and after turning the screw merely a few revolutions the grip is loosened enough to make the screw free of the edge of the aperture, and it can then be withdrawn without further turning, as contrasted to the condition when a rusted nut should be turned loose and out of a bolt thread.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A clamping device comprising a holder and a yoke for embracing an object and a screw engaging the holder yoke for moving the yoke relative to the holder so as to clamp the object between the yoke and holder, characterized in that the screw is tapered and has a helical thread in threaded engagement with the holder, the screw extends across the yoke and a portion of the yoke extends around the screw with a face of the yoke in contact with a part of the periphery of the screw such that rotation of the screw relative to the holder advances the screw across said portion of the yoke so as to displace the yoke relative to the holder.

2. A device as claimed in claim 1, in which the screw extends through an aperture in an end portion of the holder, and the thread of the screw engages an edge of the aperture so that the screw is advanced through the aperture when the screw is turned.

3. A device as claimed in claim 1 or 2, in which the yoke has opposite ends connected to opposite ends of the holder and the portion of the yoke extending around the screw is a curved part of the yoke between the opposite ends of the yoke, the arrangement being such that another portion of the yoke is stretched when the screw is advanced across the yoke.

4. A device as claimed in claim 1, in which the holder includes a tongue which extends through a slot in an end portion of the yoke, and in which the screw extends into an aperture in said tongue with the thread of the screw in engagement with an edge of the aperture and the periphery of the screw abutting against said face of the yoke on opposite sides of the slot and thereby being guided for longitudinal displacement.

5. A device as claimed in claim 4, in which an outermost end of the slot is capable of being hooked upon the tongue and retained by a step in the edge of the tongue.

6. A device as claimed in claim 1, in which the holder comprises two parallel, spaced apart plates, this yoke extends between the two parallel plates and the screw extends through opposed apertures in said plates and has one side in contact with the yoke and an opposite side in contact with the edges of the apertures in the plates.

7. A device as claimed in claim 6, in which the relative positions of the apertures are such that the axis of the screw is inclined from a perpendicular to the plates and the side of the screw in contact with the yoke is perpendicular to said plates.

8. A device as claimed in claim 1, in which the cross-section of the screw is angular or toothed.