GB2449116A

GB2449116A - Worm screw clamp with plastic strap

Info

Publication number: GB2449116A
Application number: GB0709082A
Authority: GB
Inventors: Christopher Leslie Hill
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-11
Filing date: 2007-05-11
Publication date: 2008-11-12
Anticipated expiration: 2027-05-11
Also published as: GB2449116B; GB0709082D0

Abstract

A clamp 101 comprises a flexible strap 102, the strap fabricated from a first plastic material and having a plurality of longitudinally spaced teeth 103 and a housing 105. The clamp further comprises a worm screw 108 configured to engage with the teeth of the strap. The housing 105 is configured to receive the worm screw 108 and an end of the strap such that the diameter of the clamp is adjustable by rotation of the worm screw. The worm screw may be fabricated from a second plastic material, which may be acetal. The first plastic material may be nylon. The clamp 101 is configured such that when the plastic strap 102 is engaged within the housing 105, a plurality of the teeth 103 are disposed to mesh simultaneously with a plurality of turns 401 of the worm screw. A method of manufacturing the clip, comprising first and second moulding operations to mould the strap and worm screw from first and second plastic materials respectively is also disclosed.

Description

A Clip

Technical Field

The present invention relates to a clip, in particular a worm drive clip.

Background of the Invention

Worm drive hose clips are available that are fabricated from metal, such as stainless steel, mild steel that is zinc plated or mild steel that is cadmium plated. It is found that the grooved strap of a metal worm drive clip is often inflexible to the extent that the worm drive engages with the grooves of the strap at a tangent to the band formed when the strap is engaged with the worm drive. As a consequence of the tangential connection of the worm drive with a single groove of the strap, the grip provided by the clip is prone to slippage.

In addition, some metal clips are found to be electrically conductive and are found to experience corrosion. Such characteristics of metal clips are undesirable as prohibiting them from use in some applications, for example in food processing environments.

Further, metal worm drive hose clips are known that utilise the same metal for both the worm drive and the strap. A problem with this arrangement is that the metal components tend to lock together. This problem is exacerbated where a coating is used over the substrate metal. The coating may be worn off during use of the clip, exposing the substrate metal of the strap to corrosion. Corrosion of the strap is found to increase the incidence of locking with a co-operating component of the same metal fabrication.

Brief Summary of the Invention

According to a first aspect of the present invention, there is provided a clip comprising: a flexible strap having a plurality of longitudinally spaced teeth and a housing, and a worm screw configured to engage with said teeth; said housing configured to receive said worm screw and to receive an end of said strap such that the diameter of the clip is adjustable by rotation of said worm screw, wherein said strap is fabricated from a first plastic material.

According to a specific embodiment, said worm screw is fabricated from a second plastic material that is different from said first plastic material.

The clip is configured such that when the plastic strap is engaged within the housing, a plurality of the teeth are disposed to mesh simultaneously with a plurality of turns of the worm screw.

According to a second aspect of the present invention, there is provided a method of manufacturing the clip, said method comprising the steps of: performing a first moulding operation to mould said strap from a first plastic material.

Brief Description of the Several Views of the Drawings Figure 1 shows a clip; Figure 2 shows the clip of Figure 1 in use; Figure 3 shows the clip of Figure 1 being reconfigured from a disengaged condition into an engaged condition; Figure 4 shows a cross-sectional view of the clip of Figure 1 in the engaged condition; Figure 5 shows a cross-sectional view showing the engaged condition of the clip of Figure 4 in further detail; Figure 6 shows a first type of adjustment extension of a clip; Figure 7 shows a second type of adjustment extension of a clip; Figure 8 shows a third type of adjustment extension of a clip; Figure 9 shows the clip of Figure 1; Figure 10 shows an environment in which a plurality of clips of the type shown in Figure 1 is being used; Figure 11 shows steps of a first method of manufacture of a plastic clip; Figure 12 shows a clip manufactured by the method of Figure 11; Figure 13 shows steps of a second alternative method of manufacture of a plastic clip; Figure 14 shows a clip manufactured by the method of Figure 13; Figure 15 shows a clip of the type shown in Figure 1.

Description of the Best Mode for Carrying out the Invention Figure 1 Figure 1 shows a clip. Clip 101 comprises a flexible strap 102 having a plurality of longitudinally spaced teeth, such as tooth 103, located towards a first end 104 and a housing 105 located towards the second end 106. Housing 105 defines a cylindrical bore 107 therethrough configured to receive a cylindrical worm screw 108 having a helical thread, and also defines a slot 109 therethrough configured to receive the first end 104 of the flexible strap 102.

The worm screw 108 is operatively accommodated within the housing 105, and is configured to engage with the teeth 103 of the flexible strap such that the diameter of the clip is adjustable by rotation of the worm screw 108. To facilitate rotation of the worm screw, adjustment extension 110 is presented.

In the illustrated example, the teeth 103 take the form of projections.

Along with the teeth 103, the housing 105 is an integral part of the strap 102.

The flexible strap 102 presents a shoulder 111, where the flexible strap 102 bends before presenting the second end 106. In this example, the strap is tapered at the second end 106. Housing 105 is located upon the flexible strap 102 between the corner of the shoulder 111 and the second end 106. In this example, the shoulder 111 bends through ninety (90) degrees, and the housing 105 is located at the free end of the shoulder 111 such that the threaded bore 107 and the slot 109 therethrough extend substantially perpendicularly to the other end of the shoulder 111.

In Figure 1, clip 101 is shown in a disengaged condition in which the first end 104 of the flexible strap 102 is disengaged from the worm screw 108.

The flexible strap 102 of clip 101 is fabricated from a first plastic material, such as nylon, polyethylene or polypropylene.

In a specific embodiment, the worm screw is fabricated from a second material that is different to the first plastic material of the flexible strap, such as a second plastic material.

In a specific embodiment, the strap 102 is fabricated from nylon and the worm screw is fabricated from acetal having high tensile strength.

Figure 2 Clip 101 is shown in Figure 2 being utilised as a clamp, and is encircled around a first hose 201 to secure an end of the first hose 201 around an end of a second hose 202. The diameter of the clip 101 is adjustable. This feature allows the clip 101 to be used with components of differing diameters and also allows the degree of grip of the clip around a component to be varied.

Figure 3 As illustrated in Figure 3, the clip 101 may be reconfigured into the engaged condition by firstly inserting the first end 104 of the flexible strap 102 into the slot 109 of the housing 105. In the illustrated example, the first end 104 is tapered to facilitate location and insertion of the strap 102 into the housing 109. The teeth 103 of the strap 102 may then be engaged with the worm screw 108 by rotation of the adjustment extension 110 to, in turn, rotate the worm screw 108.

In a specific embodiment, the clip is reconfigurable from the disengaged condition into the engaged condition and subsequently reconfigurable from the engaged condition back into the disengaged condition.

The use of plastic material in the fabrication of the strap serves to provide an increase in the flexibility of the strap and serves to decrease the weight of the clip when compared to a clip of a similar type that is fabricated from metal material. Further, it is found that the plastic strap 102 is able to flex on entry into the slot 109 of the housing 105, to facilitate movement of the strap through the housing 105.

Figure 4 A cross-sectional view of the clip 101 in the engaged condition as shown in Figure 2 is shown in Figure 4. As shown, when in the engaged condition, the strap 102 of the clip 101 forms a gripping loop.

The clip is configured such that when the plastic strap 102 is engaged within the housing 105, a plurality of the teeth 103 are disposed to mesh simultaneously with a plurality of turns, such as turn 401, of the worm screw 108.

This feature provides for an increase in the length of contact L between the teeth 103 of the strap 102 and the worm screw 108 than, for example, is found with a metal strap of a metal hose clip. This feature functions to improve the security of the grip of the clip in use, to reduce slippage of the grip.

By the use of different plastic materials in the fabrication of the strap 102 and the worm screw 108, locking of the teeth 103 of the strap and the turns 401 of the worm screw can be prevented. It is found that when the same material is utilised for both the strap 102 and the worn, screw 108 components, sticking or welding between the two components arises.

Clip 101 is shown around hose 102, with the strap 102 of the clip 101 following the contour of the circular section of the hose 102 around the majority of the circumference of the hose 102. Thus, the gripping loop of the clip 101 offers a substantially circular gripping configuration. The diameter of the clip 101 is adjustable by means of operation of the worm screw 108 to progress the teeth 103 in a direction that acts to tighten or loosen the clip.

In the illustrated example, the cross-section of the shoulder 111 of the strap 102 is greater than that of the strap 102 between the shoulder 111 and the teeth 103. This improves the strength of the clip in the area where the strap extends from the housing position.

However, it is to be appreciated that the dimensions of the shoulder 111 can affect the gripping loop of a particular size of clip.

As shown, the teeth 103 project from the general thickness of the strap 102. This feature provides a greater thickness to the teeth and hence improves the strength of the teeth. This form of the teeth is considered to be preferable to, for example, teeth formed by providing grooves recessed from the general thickness of the strap, as may be found in a metal strap, since it is considered undesirable to weaken the strap where it will coact with another mechanical part of the clip.

Figure 5 Figure 5 shows a cross-sectional view of the clip 101, showing engagement of the strap 102 with the worm screw 108 in further detail. The worm screw is arranged to rotate about an axis 501.

The clip is tightened by rotation of the worm screw 108 in a first direction, indicated by arrow 502. The clip is loosened by rotation of the worm screw 108 in the second opposite direction, indicated by arrow 503.

Each tooth 103 is spaced along the strap and extends across the strap 102 at an angle to correspond with the pitch of the thread of the worm screw 108. The teeth 103 are profiled to complement the profile of the thread of the It can be seen that when the strap 102 is advancing in the tightening direction 502, the thread of worm screw 108 presents a substantially planar contact face 504 for contact with a substantially planar contact face 505 of the teeth 103. The worm screw tightening contact face 504 and the teeth tightening contact face 505 both extend substantially perpendicularly to the direction of travel of the teeth 103.

It can further be seen that when the strap 102 is advancing in the loosening direction 503, the thread of worm screw 108 presents a substantially planar contact face 506 for contact with a substantially planar contact face 507 of the teeth 103. The worm screw loosening contact face 506 and the teeth loosening contact face 507 both extend substantially obliquely to the direction of travel of the teeth 103. The loosening contact faces 506, 507 of the worm screw 108 and the teeth 103 both slope towards the free edge of the opposite tightening face 504, 505 respectively. The angles of incline of face 506 of worm screw 108 and face 507 of the teeth 103 are selected to facilitate meshing between the teeth 103 and the worm screw 108 as the strap 102 is urged into the housing 105 by rotation of the worm screw 108.

Figure 6 In Figure 6, a first type of adjustment extension 110 of a clip is illustrated, in the form of a polygonal member 601. In this example the polygonal member 601 is a hexagonal member. However, an alternative polygonal shape may be selected. The polygonal member 601 presents an arrangement similar to the style of a coach screw head that may be driven by a tool, such as a spanner, or other different tools, such as a wrench and pliers.

Figure 7 A second type of adjustment extension 110 is illustrated in Figure 7, in the form of a screw head 701 that may be driven by a screwdriver. In this example the screw head 701 is a single slotted head. However, an alternative type of screw head, such as a cross head, may be selected.

Figure 8 Figure 8 illustrates a third type of adjustment extension 110, in the form of a manually operable member having lugs 801. The lugs 801 present an arrangement similar to that of a wing nut or a butterfly nut.

Thus, the adjustment extension 110 may be selected to be only operable through use of a tool, only by manual operation or to allow both types of drive. The type of adjustment extension may be selected with consideration as to the magnitude of grip that the clip is expected to provide in an intended application. For example, a tool drive adjustment extension may be provided in applications where it is anticipated that the worm screw will be required to experience a greater magnitude of torque during installation around a component or components. The type of adjustment extension may be selected for engagement with a tool typically used in a particular field of intended application.

It is found that the worm drive arrangement of the plastic clip provides useful user control over the degree of grip exerted by the clip around an item or group of items.

Figure 9 Figure 9 illustrates a feature of the clip 101. As described, when the clip is in the engaged condition, the strap 102 extends within the housing 105. As shown, the strap 102 may extend completely through the housing 105, producing a strap tail 901 that does not form part of the substantially circular gripping configuration of the clip 101. In some applications, it may be aesthetically or functionally desirable for a strap tail to occur. However, according to the fabrication of the clip 101, the strap tail is fabricated from a plastic material and as illustrated, may be removed from the remainder of the clip by a cutting tool. As shown in Figure 9, the characteristics of the plastic material of the strap 102 may allow the tail to be removed by use of a pair of scissors 902. Other tools may be used, such as a pair of snips, or a knife or saw, although particular types of bladed tools may be deemed hazardous to use in some environments.

Thus, any impracticality arising from the existence of a strap tail can be prevented by removal of the tail. This feature of the clip also facilitates the use of the clip with components over a comparatively wide range of diameters.

Hence, the ability to shorten the plastic strap 102 enables a particular clip to be used over a wider range of diameters than, for example, a metal hose clip of a similar size.

This feature may facilitate swift removal of an installed clip, since the strap can be severed to break the gripping configuration of the strap. In some circumstances, this action may be preferable to operating the worm screw to release the clip into the disengaged condition although the clip would subsequently be unfit for reuse.

Plastic material used in the composition of the clip may also be selected to improve the disposability of the clip, in particular to improve the recycling options of the clip once it has reached the end of its working life.

Figure 10 An industrial environment 1001 in which a plurality of clips of the type of clip 101 is employed is shown in Figure 10.

The plastic clips 1002, 1003 are suitable for use in a corrosive environment or in an environment containing chemicals or food.

The plastic material used in the fabrication of the clip renders the plastic clips 1002, 1003 suitable for use in environments where the use of metal clips may not be considered for use for a similar purpose. For example, although it is desirable to avoid contamination of an environment by a portion of a clip used within that environment, it is considered that contamination by means of a portion of plastic is less of a safety concern than contamination by means of a portion of metal.

In some applications, the material from which the plastic clips are fabricated may be selected to withstand a particular temperature. For example, in an environment containing boiling water, a plastic material may be selected to withstand a temperature elevated beyond the boiling point of water, for example one hundred and fifty degrees Celsius (150 C).

In some applications, the material from which the plastic clips are fabricated may be selected to withstand a sterilising procedure.

Figure 11 Figure 11 illustrates steps in a first method of manufacture of a plastic clip of the type of clip 101.

According to the method of Figure 11, first and second independent moulding operations are performed.

At step 1101, a first plastic material is received and at step 1102 a first moulding operation is performed to mould the strap, with integral teeth and housing, from the plastic material A. At step 1103, a second plastic material is received and at step 1104 a second moulding operation is performed to mould the worm screw from the plastic material B. The manufacturing process of Figure 11 produces two separate components. At step 1105, a strap and a worm screw are assembled to produce the clip.

It is to be appreciated that the moulding operation to produce the strap of the clip may be performed at a separate location to the location at which the moulding operation to produce the worm screw of the clip is performed.

Further, the assembly of the clip may be performed at a different location to where one or both of the moulding operations are performed. Locations for performing steps 1102, 1104 and 1105 may be selected in accordance with technical or commercial motivations. Thus, in practice, components moulded at steps 1102 and/or 1104 may be transported between locations for assembly.

Assembly of the components is preferable prior to being supplied for retail or use to avoid components being lost and to avoid the inconvenience of assembling the clip in anticipation of use in the desired application.

In a specific embodiment, the worm screw of the clip is fabricated from acetal with 40% PTFE (polytetrafluoroethylene) lubricant, and the strap of the clip is fabricated from nylon 66, nylon 610 or nylon 612. A suitable acetal (POM) material is available as Lubricomp KL-4040 from Solutia Inc. Missouri, U.S.A. A suitable nylon resin material is available as Vydyne 21SPC from General Electric Company, New York, U.S.A. The length of the strap may be approximately 12.7 cm (5 inches), 20.3 cm (8 inches) or 27.9 cm (11 inches).

A clip may be fabricated from these materials that will withstand an applied driving torque of 4Nm.

Figure 12 Components of a clip manufactured by the method of Figure 11 are shown in Figure 12. To assemble the worm screw 1201 and strap 1202, to form a clip, the worm screw 1201 is inserted into the bore 1203 of the housing 1204. The worm screw 1201 is directed towards the bore 1203 in the direction of arrow 1205, which is the opposite direction to which the first end 1206 of the strap is inserted into the housing. 1203 for engagement with the worm screw.

The worm screw 1201 is then inserted into the bore 1203 of the housing 1204, with the gripping member 1207 left outside the housing. The bore 1203 of housing 1204 has a smooth internal surface allowing the worm screw 1201 to be simply pushed therein.

Figure 13 Steps in a second method of manufacture of a plastic clip of the type of clip 101 are Uustrated in Figure 13.

According to the method of Figure 13, a two-shot injection moulding operation is performed. First and second moulding operations are performed such that the second moulded component is joined to the first moulding component.

At step 1301, a first plastic material is received and at step 1302 a second plastic material is received. A first moulding operation is performed at step 1303 to mould the strap, with integral teeth and housing, from the plastic material A. At step 1304 a second moulding operation is performed to mould the worm screw from the plastic material B such that the worm screw is joined to the strap moulded at step 1303.

The manufacturing process of Figure 13 produces a unitary piece.

At step 1305, the strap and the worm screw are separated and are assembled to produce a clip at step 1306. Once the strap and the worm screw are separated from each other, assembly may proceed as described with reference to Figure 12.

Figure 14 Components of a clip manufactured by the method of Figure 13 are shown in Figure 14.

An advantage of the manufacturing process of Figure 14 is that the components of the clip are produced as a unitary piece 1401 that may be supplied for use in the unassembled state. The unitary piece 1401 is substantially flat, making it conveniently transportable.

Assembly is not required prior to being supplied for retail or use, potentially bringing a reduction in the unit cost of supply of each clip.

Figure 15 Figure 15 shows a clip 1501 of the type, and in the assembled state, of clip 101 as shown in Figure 2.

Since the strap 1502 of the clip 1501 is fabricated from a plastic material, the clip 1501 may include self-colouring and/or may carry a graphical indication, such as graphical indication 1503. A graphical indication may be printed onto the clip or may be formed during moulding of the clip, in relief or intaglio form. Thus, the clip 1501 may desirably provide one or more visual indications. The nature of such an indication may serve to provide a warning, for example as to the presence of a hazardous substance that may flow through a pipe upon which the clip is used. Alternatively, a clip may present an indication simply to provide a means of identifying between items contained in a receptacle having an opening that is closed with the clip. Thus, for example, a clip may be selected from a range of differently coloured clips to indicate a type of liquid within a storage vessel.

Claims

Claims 1. A clip comprising: a flexible strap having a plurality of

longitudinally spaced teeth and a housing, and a worm screw configured to engage with said teeth; said housing configured to receive said worm screw and to receive an end of said strap such that the diameter of the clip is adjustable by rotation of said worm screw, wherein said strap is fabricated from a first plastic material.
2. A clip according to claim 1, wherein said worm screw is fabricated from a second plastic material that is different from said first plastic material.
3. A clip according to claim 1 or claim 2, The configured such that when said plastic strap is engaged within said housing, a plurality of said teeth are disposed to mesh simultaneously with a plurality of turns of said worm screw.
4. A clip according to any of claims 1 to 3, further comprising an adjustment extension to facilitate rotation of the worm screw.
5. A clip according to claim 4, wherein said adjustment extension is manually operable.
6. A clip according to any preceding claim, wherein said first plastic material is nylon.
7. A clip according to any preceding claim, wherein said second plastic material is acetal.
8. A method of manufacturing a clip according to claim 1, said method comprising the steps of: performing a first moulding operation to mould said strap from a first plastic material.
9. A method according 8, wherein said method further comprises the step of performing a second moulding operation to mould said worm screw from a second plastic material that is different from said first plastic material.
10. A method according to 9, wherein said first and second moulding operations are performed so as to join said strap and said worm screw.
11. A method of manufacturing a clip substantially as herein described with reference to and as shown in the accompanying Figures. * . * * * a * .1 a.. * a a... a * * a * *. a as. a * a *aa a *a. a

11. A clip substantially as herein described with reference to and as shown in the accompanying Figures.

12. A method of manufacturing a clip substantially as herein described with reference to and as shown in the accompanying Figures.

Amendments to the claims have been filed as follows I' Claims 1. A clip comprising: a flexible strap having a plurality of longitudinally spaced teeth and a housing, and a worm screw configured to engage with said teeth; said housing configured to receive said worm screw and to receive an end of said strap such that the diameter of the clip is adjustable by rotation of said worm screw, wherein io said strap is fabricated from a first plastic material, and said worm screw is fabricated from a second plastic material that is different from said first plastic material.

2. A clip according to claim I configured such that when said plastic strap is engaged within said housing, a plurality of said teeth are disposed to * mesh simultaneously with a plurality of turns of said worm screw. * *. * . . * *.

* **.. * 3. A clip according to either of claims 1 or 2, further comprising an adjustment extension to facilitate rotation of the worm screw. * S. * S. * 20

S

4. A clip according to claim 3, wherein said adjustment extension is r*. manually operable.

S S..

S

5. A clip according to any preceding claim, wherein said first plastic material is nylon.

6. A clip according to any preceding claim, wherein said second plastic material is acetal.

7. A method of manufacturing a clip according to claim 1, said method comprising the steps of: (7 performing a first moulding operation to mould said strap from a first plastic material.

8. A method according 7, wherein said method further comprises the step of performing a second moulding operation to mould said worm screw from a second plastic material that is different from said first plastic material.

9. A method according to 8, wherein said first and second moulding operations are performed so as to join said strap and said worm screw.

10. A clip substantially as herein described with reference to and as shown in the accompanying Figures.