GB2150205A - Worm driven band clamp - Google Patents

Abstract

A band clamp has slots 32 cut in one end of the band and a housing 41 containing a screw 51 anchored at the other so that its threads 53 can engage the slots 32 to tighten the band. The housing 41 is held on the band with the underside 43a of its saddle held between projections 33, 34 formed in the end of the band which also has a hole 35 through which the screw threads engage slots 32. <IMAGE>

Description

SPECIFICATION Worm-band fastener The present invention relates to a worm-band fastener such as is used in the connection of hoses and the like.

In general, a worm-band fastener comprises a band having adjacent one end thereof screw-thread slots, and a housing fixed on the other end of the band with a rotatable worm screw mounted in the housing. The slotted end is inserted through the front opening ofthe housing and engaged with the worm screw so as to form a loop which can be tightened up to fasten an object, such as a hose. In such a worm-band fastener, there have been proposed various structures for retaining the housing on the band, but they all involve some defects which interfere with their practical use.

An example of such a structure is shown in Figure 1, in which a saddle portion 2 of a housing 1 is provided with lugs 3 atthe underside 2a thereof. The lugs 3 are symmetricallybentand extended through an aperture Sin the band 4to retain the housing 1 on the band 4.

However, the structure is noteasyto assemble and it also fails to ensure consistency in quality. Furthermore, when the worm screw 6 is tightened, the rigidity of the housing 1 becomes insufficient, resulting in a spreading ofthefolded lugs ofthe saddle portion 2 adapted for holding the band 4, or lifting of the underside 2a away from the band 4. These problems have caused wrenching, tearing andlor twisting of the lugs 3.Incomplete engagement results between the thread of worm screw 6 and the slots of the band 4. lfthe lugs 3 are made largerto withstand a high fastening force, both the housing 1 and band 4 must be made asthickand wide as possible, or on the contrary, if the lugs 3 are made thinner and narrower, cracking and breaking will resultwhen the housing 1 is heattreated after its formation.

Figure 2 shows another example of such a structure in which the underside 12a ofthe saddle portion 12 of the housing 11 is provided with a trapezoid (as shown in the drawing) or circular projection 13 and a perforation 14 in which is engaged the projection 13.

Also in this case, insufficient rigidity ofthe housing 11 causes the same reduced or inoperative fastening force as in the structure shown in Figure 1.

Figure 3 shows a further example in which the underside portions 22a of the saddle portion 22 of the housing 21 are bent toward the centre line ofthe band 23 untitthe respective ends thereof contact with one another. One end ofthe band 23 is inserted into the saddle portion 22 and then fixed byspotwelding.

Such a structure suffers, in addition to the defects of the structures in Figures 1 and 2, from the problems thatthe housing 21 may shift in the longitudinal direction of the band 23 or come off dueto possible incomplete welding.

According to the present invention, there is provided a worm-band fastener including a band having screw4hread slots adjacent one end and a housing formed from a single blank of seamless tubular metal mounted on the other end, a worm screw being rotatably mounted in said housing; the housing having a portion of part circular cross-section with said worm screwtherein and a saddle portion by which it is mounted on said other end of said band; said band having adjacent said other end a pair of spaced projections for contacting and restraining the front and rear edges ofthe underside of said saddle portion; said one end of said band being insertable through an opening atthe front of said housing so that the slots can engage with said worm screw.

The present invention allowsthedisadvantages associated with the prior artto be reduced. With the invention, a high fastening force can be exerted by employing a worm screw housing which is simple in construction and has high rigidity, while in use the worm screw may be smoothly tightened.

The portion ofthe housing of part circular crosssection may be tapered or semi-cylindrical.

In orderthatthe invention may be more clearly understoodthefollowing description is given byway of example only, with referenceto the accompanying drawings, in which:~ Figures 1 to 3 are perspective views illustrating various prior art constructions for retaining a housing on a band in a worm-band fastener; Figure 4 is a perspective view similar to Figures 1 to 3, illustrating the construction according to the first embodiment of the present invention; Figure 5 is a front view ofthe first embodiment ofthe present invention; Figure 6 is a side elevational view of Figure 5; Figure 7 is a sectional viewtaken along line VII-VII in Figure 5; Figure 8 is an enlarged vertical sectional view of the essential parts in Figure Sin which the extreme end of the worm screw is hammered;; Figure 9 is a sectional viewtaken along line IX-IX in Figure 8; Figure 10 is a perspective view of one end of the band; Figure 11 is a frontview of a worm-band fastener according to the second embodiment of the present invention; and Figure 12 is a vertical sectional view of the essential parts of Figure 11.

Referring newto Figures 4to 10in which the first embodimentofthe present invention is shown, numeral 31 indicates a narrow elastic band having slots 32 stamped therein at regular pitches from one end 31 a thereof. The band 31 has adjacent the other end 31 bthereoftwo projections 33 and 34 provided in spaced opposing relationship to each other, as shown in Figure 10. The projections 33 and 34 are formed by press bending, drawing or like operation along notches provided in the transverse direction ofthe band 31. The band 31 further has an elongated aperture 35 disposed in the longitudinal direction of the band 31 between the projections 33 and 34.The slots 32 are aligned in sequence from the end 31 a of the band, the last one thereof being followed by holes 36a and 36bwhich are progressively smaller in area than the slots 32. Numeral 41 indicates a housing which is tightly held between the projections 33 and 34 provided adjacent the end 31 b ofthe band 31, and a worm screw 51 is inserted into the housing 41. The housing 41 is formed from a single blank of seamless tubular metal and has a semi-cylindrical portion 42 for accommodating the worm screw 51 therein and a saddle portion 43 adapted to be mounted on the band end 31b, which are integrally formed by drawing operation. The underside 43a ofthe saddle member43 has at the front and rear edges thereof raised corners 43b adapted to be engaged with the projections 33 and 34 of the band 31.The semi-cylindrical portion 42 has at the front end 42a thereof an end wall 44 provided with a semi-circularguide aperture 44ato serve as a guide for rotatablysupporting the extreme end 51 a of the worm screw 51.

The worm screw 51 has a shank 52 extending rearwardlyfrom the extreme end 51 a and having screw th reads 53. The shank 52 is provided at the rear endthereofwith ashoulder54which is larger in diameterthan the shank 52 adapted to be abutted againstthe rear end surface of the housing 41 when the worm screw 51 is inserted thereinto. A hexagon head 56 is provided through a flange 55 atthe back of the shoulder 54. The extreme end 51 a of the worm screw may be formed with a hammered portion 57 to enlarge the diameter of a portion extruding out of the guide aperture 44a so as to prevent the worm screw 51 from coming out ofthe housing 41 when the worm-band fastener is out of use.

Now the operation of the worm-band fastener thus constructed is as follows. The saddle portion 43 of the housing 41 is mounted on the end 31 b ofthe band 31, the raised corners 43b atthe front and rear edges of the underside 43a being fittingly placed between the projections 33 and 34 ofthe band3l.Then,theworm screw 51 is inserted into the semi-cylindrical portion 42 of the housing,theextreme end 51a being fitted into the guide aperture 44a ofthe semi-cylindrical portion 42. Thus, the guide aperture 44a assures smooth positioning and rotation of the worm screw 51. The band 31 is wound around an object such as a hose andthe end 318 is inserted into the housing 41 through the front end thereof between the worm screw 51 and the band end 31 b.The hexagon head 56 ofthe worm screw 51 is rotated as by a hexagon wrench orthe like in the tightening direction. Then the screw th reads 53 are engaged with the slots 32, and as the worm screw 51 is rotated, the band 31 is wound up to fasten the hose orthe like.

During the use ofthe worm-band fastener, reaction force will be produced from continued fastening action. Thus, the projection 33 of the band end 31 b presses the lowerfront corner 43b of the saddle portion 43, andthe rearendsurfaceofthesemi- cylindrical portion 42 presses the shoulder 54 of the worm screw 51. As the result, the housing 41 is pressed atthe rear end surface of the semi-cylindrical portion 42 bythe shoulder 54 ofthe worm screw 51, and the lowerf ront corner 43b of the saddle portion 43 is pressed through reaction force from the projection 33 on the band end 31 b.Furthermore, reaction force will be developed from the band 31 and the worm screw 51 to the side wall of the semi-cylindrical portion 42 and the side wall and the underside 43a of the saddle portion 43, and torsional stress will be produced on tha housing 41 every time torque is applied to the worm screw 51. However, since the housing 41 isformed from but a single blank of seamlesstubularmetal, it has sufficient rigidityto ensure full tightening of the band 31, without causing possible deformation of the housing 41 or loose or out of engagement of the worm screw 51. When the threads 53 are engaged with the slots 32, the crests of the threads 53 are projected out of the slots 32 into the aperture 35 ofthe band end 31 b, resulting in more reliable engagement.As the last slot 32a is followed by the holes 36a and 36bwhich become gradually smaller, concentration of stress is prevented, thereby eliminating the possibility of breakage ofthe band 31 atthesection of the last slot 32awhich would be caused when the band 31 is bent around the hose or the like. The worm screw 51 having the extreme end 51 a thereof a hammered portion 57 will not slip out of the housing 41 whilethe fastener is out of use, permitting ease of handling.

Figures 11 and l2showanotherembodimentofthe present invention which is different from the first embodiment in that a housing 61 and a worm screw 71 are formed in a tapered configuration. Like parts are given like reference numbers and anyfurtherdescription will be omitted. The housing 61 is formed by drawing and has integrally formed a tapered semicylindrical portion 62 for accommodating theworm screw 71 therein and a saddle portion 63to be mounted on the band end 31 b. The housing 61 is tightly held between the two projections 33 and 34.

The underside 63a of the saddle portion 63 has atthe front and rear edges thereof raised corners 63a adapted to be engaged with the projections 33 and 34.

Thetapered semi-cylindrical portion 62 has atthe front end 62athereof an end wall 64 provided with a semi-circular guide aperture 64afor rotatably support ingthe extreme end 71aoftheworm screw71.

The tapered worm screw 71 has atapered shank 72 extending reannra rdly from the extreme end 71 a and having screw threads 73. The shank 72 is provided at the rear end thereof with a shoulder 74 which is larger in diameterthan the shank 72 and adapted to be abutted against the rear end surface of the housing 61 when the worm screw71 is inserted thereinto. A hexagon head 76 is provided through a flange 75 atthe back ofthe shoulder74.The extreme end 71 a of the worm screw may be formed with a hammered portion 77, as isthe case in thefirst embodiment The worm-band fastenerthus constructed has substantially the same operational effect as that of the first embodiment, and further permits smooth tightening operation oftheworm screw.In otherwords, owing to the tapered semi-cylindrical portion 62 and the forwardly inclining inner configuration of the saddle portion 63,theworm screw71 is drawn forward to thereby exert a pressing forceto the tapered semi-cylindrical portion 62 and band end 31 b, when the worm screw 71 is rotated in the tightening direction. Now, the threads 73 oftheworm screw71 are always maintained in tight engagement with the inner periphery of the tapered semi-cylindrical portion 62 and the slots 32 of the band end 31 b, resulting in smooth tightening operation oftheworm screw 71.

While the invention has described with reference to preferred embodiments thereof, it isto be understood that modifications orvariations may be easily made without departing from the scope of this invention which is defined by the appended claims.

Claims (8)

1. A worm-band fastener including a band having screw-thread slots adjacent one end and a housing formed from a single blank of seamless tubular metal mounted on the other end, a worm screw being rotatably mounted in said housing; the housing having a portion of part circular cross-section with said worm screwtherein and a saddle portion by which it is mounted on said other end of said band; said band having adjacent said other end a pair of spaced projectionsforcontacting and restraining the front and rear edges ofthe underside of said saddle portion; said one end of said band being insertable through an opening atthefrontofsaid housing so that the slots can engage with saidworm screw.

2. A worm-band fastener according to claim 1 including, at the front of the housing, a guide means adapted for supporting the end of said worm screw.

3. Aworm-band fastener as defined in claim 2 wherein the end of said worm screw projecting out of the guide means is enlarged so as to retain the screw.

4. A worm-band fastener according to claim 1,2 or 3 including an elongated longitudinal apertureformed in the band between said projections so as to avoid interference with said worm screw.

5. Aworm-band fastener according to claim 1,2,3 or4wherein said band has a plurality of holes adjacent that one of the slots which is furthest from said one end, said holes being in a direction away from said one end, of progressively smaller area.

6. A worm-band fastener according to any preceding claim wherein the worm screw is of generally tapered configuration and the portion of the housing of part circular cross-section is tapered correspondingly.

7. A worm-band fastener according to any one of claims 1 to 5 wherein the portion ofthehousing of part circular cross-section is semi cylindrical.

8. A worm-band fastener substantially as hereinbefore described with reference to and as illustrated in Figures4to 10 or 11 andl2oftheaccompanying drawings.