EP0688259B1 - Tool handle - Google Patents

Description

The present invention relates to a tool handle of the type consisting of at least two materials plastics and comprising, on at least part of its length, a plastic outer sheath relatively flexible overmolded on a support sleeve.

Such a tool handle is known in the interior art, for example, by document WO-A-93/25354.

We also know from document EP-A-0635337, which constitutes an intermediate patent application within the meaning of Article 54 (3) EPC, a handle tool of the type defined in the preamble of claim 1 comprising a support sleeve which has a harder plastic than that of the outer sheath.

The invention applies to various tools for hand such as pliers, screwdrivers, etc.

Tool handles of the above type have the advantage of offering the user a touch both non-slip and resistant which allows to exercise significant efforts under very good conditions comfort.

However, the technology for achieving these tool handles is tricky because it has to allow ensure excellent hold at low cost in time of the outer sheath, despite its exposure frequent in aggressive environments such as automotive fuels, "White Spirit", trichloroethane and other aromatics. On the other hand, it is necessary to ensure resistance of the handle to the efforts of tightening and possibly torques.

However, current solutions do not provide simultaneously resistance to efforts, resistance to aggressive backgrounds and the relatively flexible touch of the outer surface.

To solve this problem, the invention offers a tool handle of the aforementioned type, characterized in that the outer sheath consists essentially a flexible grade polyester elastomer, and is overmolded on a support sleeve consisting of a material based on a polyester elastomer of grade hard.

The support sleeve can be formed essentially of a grade polyester elastomer hard.

The outer sheath can be made said substantially pure polyester elastomer, and it can be the same for the support sleeve.

In certain cases, in particular to cover the branches of pliers, the support sleeve can be directly in contact with the underlying metal part of the tool, of which it is secured by friction and / or by marriage of conjugated forms.

In other cases, where the tool handle is intended to transmit significant couples, in particular for coating a screwdriver blade, the support sleeve can surround an essentially tubular element of bond made of a third plastic plus lasts longer than that of the support sleeve and connected to the part metal underlying the tool by friction and / or by marriage of conjugated forms.

The connecting element can then be molded in the support sleeve.

• la Figure 1 est une vue en coupe longitudinale d'un tournevis muni d'un manche tri-matière selon l'invention;
• la Figure 2 est une vue en coupe suivant la ligne 2-2 de la Figure 1;
• la Figure 3 est une vue en coupe suivant la ligne 3-3 de la Figure 1;
• la Figure 4 est une vue en coupe longitudinale d'un manchon bi-matière utilisé pour la fabrication du manche de tournevis de la Figure 1; et
• la Figure 5 est une vue partielle, partiellement en coupe, d'une pince coupante dont chaque branche est équipée d'un manchon bi-matière conforme à l'invention.

Examples of embodiments of the invention will now be described with reference to the appended drawings, in which:

• Figure 1 is a longitudinal sectional view of a screwdriver provided with a tri-material handle according to the invention;
• Figure 2 is a sectional view along line 2-2 of Figure 1;
• Figure 3 is a sectional view along line 3-3 of Figure 1;
• Figure 4 is a longitudinal sectional view of a bi-material sleeve used for the manufacture of the screwdriver handle of Figure 1; and
• Figure 5 is a partial view, partially in section, of a cutting pliers each branch of which is equipped with a bi-material sleeve according to the invention.

The screwdriver 10 shown in Figure 1, of general axis X-X supposed horizontal, includes a rod metal 12 forming a blade provided with a recessed end 14 in a handle 16 of tri-material plastic according to a first embodiment of the invention.

Conventionally, the embedding end 14 of the blade 12 has a flattened end 15 intended to reinforce the rotation blocking of the blade 12 around of its axis.

The handle 16 includes a sleeve 18 surrounding a connecting element 20 in which is embedded the blade 12.

The sleeve 18 comprises two tubular parts coaxial, i.e. an inner support sleeve 22 and an outer sheath 24, made of materials different plastics. More specifically, the support sleeve 22 is made of a polyester elastomer of hard grade (hardness 72 Shore D), while the sheath 24 consists of a grade polyester elastomer flexible (hardness 35 Shore D), overmolded on the support sleeve.

The elastomers in question can be practically pure. The flexible grade elastomer can incorporate mineral fillers, including colorants and / or rheological agents. Pure grade elastomer can incorporate various additives more widely: fibers, mineral fillers, glass beads, blowing agents, plasticizers, etc.

As for the connecting element 20, it is made of a much harder plastic than that of the support sleeve 22, for example an acetate of cellulose, polyamide, rigid polyester or polyacetal.

The sheath 24 extends over approximately the front half of the length of the support sleeve between a annular ring 25A projecting therefrom and a front end flange 25B of the support sleeve. The connecting element 20 occupies the space between the support sleeve and blade 12; it has one end rear 20A which covers the entire rear part of the support sleeve, up to the rear face of the ring 25A, as well as a front end 20B which covers the collar 25B.

The sleeve 18 has an internal surface 26 suitable for optimally securing the sleeve 18 to the connecting part 20. For example, as can be see in particular in Figures 2 and 3, the surface internal 26 of sleeve 18 is delimited by a first part 26A, of substantially polygonal cross section, preferably square, extending from the end free from handle 16 to a second part 26B of this internal surface, of cross section substantially polygonal, preferably hexagonal, and perimeter lower than that of the cross section of the first part 26A.

As a variant, the internal surface of the sleeve 18 may have varied sections, constant or not.

We will now describe the manufacturing process the handle 16 of the screwdriver shown in Figure 1.

Initially, we manufacture the bi-material sleeve 18 as shown in Figure 4, molding by injection the support sleeve 22 and by overmolding by injection on the latter the sleeve 24.

Overmolding of the sleeve 24 on the support sleeve 22 is carried out so as to leave free the ends of the support sleeve 22.

In order to favor the attachment of the sheath 24 on the support sleeve 22, these two parts are molded so as to form on their surfaces in contact with projections and complementary recesses 28 to 34.

To make the sleeve 18, we use example a conventional press with two injection heads (one head per material to be injected).

After manufacturing the sleeve 18, place the embedding end 14 of the blade 12 inside this sleeve 18, coaxially with the latter, then we mold by injection the connecting element 20 between the blade 12 and the sleeve 18 so that the sleeve 18-element assembly 20 forms the handle 16 of the screwdriver shown in Figure 1.

The molding of the connecting part 20 is made so as to overmold the extensions 20A, 20B of this part, external to the sleeve 18, on the ends of this sleeve.

Additional projections and recesses attachment 36, 38 came from molding with the surfaces in contact with the external extension 20A of the connecting element 20, delimiting the free end or back of the handle 16, and the corresponding end sleeve 18.

The molding of the connecting part 20 is performed for example using a conventional press an injection head.

Alternatively, the end of the embedding end 14 of the blade can be flush with the free end of the handle or protrude from this end. In that case, it is possible to cover the flush end of the end of installation by a plug fixed on the end free from the handle by known means.

Of course, the manufacture of the sleeve 18 and molding the connecting part 20 can be carried out on different sites.

Thanks to the use of plastics indicated above, the sleeve 24 hooks intimately and strongly, during its overmolding, on the support sleeve 22, thanks to the affinity of the two elastomers of polyester, and this hanging remains even after a long exposure to aggressive agents such as aromatic materials. In addition, as the elastomer of hard grade constituting the support sleeve is very little sensitive to these agents, its attachment practically exclusively mechanical, by friction and conjugate forms, on the connecting element 20 is reliable and permanent. The hard plastics used for this connecting element, such as those indicated above, also have an important advantage low cost.

When there is no need to transmit high torques, the structure of the sleeve can be simplified by removing the connecting element.

So, in the case of cutting pliers (Figure 5), the support sleeve 22 has the shape of a sock with front end flange 25B, and the sheath 24 also has the shape of a sock, which covers the entire support sleeve up to the face rear of this flange 25B.

As in the case of the screwdriver handle Figures 1 to 4, the mutual affinity of the two polyester elastomers provides, when overmolding the sleeve on the support sleeve, an intimate hanging and very strong between these two parts of the handle, and this attachment resists aromatic agents.

In addition, the attachment of the support sleeve to the metal branch of the pliers is made so reliable only by friction and / or marrying of conjugate forms (classic and not shown). This results from the very weak relaxation of the stresses, over time, grade polyester elastomers hard, and their almost insensitivity to aromatic agents.

Claims (7)

1. Tool handle of the type made up of at least two plastic materials and comprising, on at least one part of its length, an exterior sleeve (24) in a relatively supple plastic material and cast moulded onto a support sleeve. It is characterised in that the exterior sheath (24) is essentially made up of a supple grade polyester elastomer, and is cast moulded onto the support sleeve (22), which consists of a material with a base of hard grade polyester elastomer.
2. Tool handle following claim 1, characterised in that the support sleeve (22) is essentially comprised of a hard grade polyester elastomer.
3. Tool handle following claim 1 or 2, characterised in that the exterior sheath (24) is made of the said practically pure polyester elastomer.
4. tool handle following any of the claims 1 to 3, characterised in that the support sleeve (22) is made up of the said practically pure polyester elastomer.
5. Tool handle following any of the claims 1 to 4 notably for pliers is characterised in that the support sleeve (22) is directly in contact with the underlying metal part of the tool, to which it is joined by friction and/or the marriage of the combined forms.
6. Tool handle following any of claims 1 to 4, notably for a screwdriver, characterised in that the support sleeve (22) surrounds an essentially tubular attachment (20), made up of a third plastic material which is harder than that of the support sleeve, and joined to the underlying metal part (14) of the tool by friction and/or by the marriage of the combined forms.
7. Tool handle following claim 6, characterised in that the attachment (20) is cast moulded into the support sleeve (22).

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