DE202007003351U1 - Screwdriver handle has outer layer of soft polymer which is bound to inner layer of harder plastic, in which shaft is embedded, radius of handle varying in different zones - Google Patents

Abstract

Screwdriver handle has an outer layer (27) of a soft polymer which is bound to an inner layer (28) of a harder plastic, in which the shaft (2) is embedded. The radius of the handle varies and it has a zone whose maximum radial extent (38) is at least 30% of its radius in that zone and a second zone whose minimum radial extent (39) is at most 60% of the maximum radial extent (38).

Description

TECHNICAL FIELD OF THE INVENTION

The The invention relates to a handle for a tool, in particular a screwdriver, according to selected features of claim 1. Furthermore, the invention relates to a hand or garden tool set. About that In addition, the invention relates to a method for measuring the radial Overall rigidity of a handle for a tool, in particular a screwdriver.

STATE OF TECHNOLOGY

For screwdrivers is a first development of a handle made of hard plastic to improve the feel in US-PS 28 71 899 has been proposed. Accordingly, on a handle core a prefabricated handle shell made of soft plastic reared. Handle core and handle shell are for transmitting torque in the circumferential direction positively via profilings connected with each other. The use of soft plastic improved the grip of the handle. In a practical test However, the known handle has been shown that the soft Handle coat under heavy loads from the hard handle core lifts off and can form wrinkles. This "walking" called lifting the handle coat of leads the handle core in particular with continuous use of the known handle to a painful blistering in the area of the palm of the hand User and inflammation causing excessive burden the hand bone.

• – hierbei lediglich in Umfangsrichtung verteilte Teilbereiche des Griffmantels bilden oder
• – in Umfangsrichtung geschlossen den Griffkern umgeben

kann, vgl. insbesondere DE 92 02 550 U1 , DE 43 04 965 A1 , DE 295 15 833 U1 , DE 195 39 200 A1 , DE 295 17 276 U1 , DE 299 00 746 U1 , DE 299 04 082 U1 . Griffe dieser Art werden heute überwiegend aus Kunststoff im Spritzgießverfahren hergestellt. Für Werkzeuge höherer Qualität werden so eine gute ergonomische Gestaltung und Haptik der Griffe angestrebt.To avoid the aforementioned disadvantages, it has been proposed in the following to join the grip core in a material-locking manner to the grip shell, wherein the soft plastic material

• - Form here only distributed in the circumferential direction portions of the grip shell or
• - Surrounded in the circumferential direction closed the handle core

can, cf. especially DE 92 02 550 U1 . DE 43 04 965 A1 . DE 295 15 833 U1 . DE 195 39 200 A1 . DE 295 17 276 U1 . DE 299 00 746 U1 . DE 299 04 082 U1 , Handles of this type are today mainly made of plastic by injection molding. For tools of higher quality, a good ergonomic design and feel of the handles are sought.

In such handles made of two plastic components, the tool is anchored in a handle core made of hard plastic, and this handle core is encapsulated with a handle shell made of soft plastic, cf. for example. EP 0 627 974 B1 , The handle shell made of soft plastic has a certain elasticity and gives a more pleasant grip than a handle, which is made only of hard plastic. Such "2-component handles" are also offered on the market for various other tools as a screwdriver, for example for trowels, pliers, saws, garden tools. Since the soft plastic also may have a higher coefficient of friction than hard plastic, higher torques can be transmitted with such a "2-component handle" as with a handle of the same size made of hard plastic. This is important for handles for screwdrivers, screw clamps, etc. Off DE 199 02 882.6 . EP 00 907 448.5 . EP 01 915 000.2 handles are still known in which the ergonomic properties are significantly improved compared to conventional handles by an asymmetrical design. A disadvantage of all these handles is that the handle shell made of soft plastic only has a thickness of about 1.5 to 3 mm, it is therefore only to a lesser extent compliant, especially since the hardness of commonly used plastics in the range of about 65 to 85 Shore A. lies. From the point of view of manufacture, the handles are standardized in certain sizes and shapes, while the users' hands have different sizes and proportions. Therefore, optimal ergonomics is not given.

With handles for screwdrivers is added that when screwing the hand, rotating the handle, continuously changing their coupling position to the handle in the circumferential direction. Therefore, the handle can not be formed in an optimal ergonomic basic shape, as in the asymmetric handles according to EP 00 907 448.5 and EP 01 915 000.2 is given, in which the hand has in use substantially a coupling position to the handle. A handle for screwdrivers must therefore have a rotationally symmetrical shape.

TASK OF THE INVENTION

The invention is based on the object, taking into account the manufacturing capabilities and the mechanical properties of a handle for a tool, especially a screwdriver, vorzu which is characterized by a good adaptability of the handle to the hand of a user.

SOLUTION

The The object underlying the invention is achieved by a handle according to the features of claim 1. Further embodiments of the handle result according to the characteristics the dependent claims 2 to 38. Another solution the problem underlying the invention is given by the Features of claim 39.

DESCRIPTION THE INVENTION

• – einerseits wird eine Anpassbarkeit des Griffkörpers an die individuelle Handform und – Größe eines Benutzers – und dazu eine Vergrößerung der Kontaktfläche zwischen Hand und Griffoberfläche – erreicht, wenn die Steifigkeit des den Griffkörper bildenden Materials verringert wird,
• – andererseits ist für eine Übertragung höherer Drehmomente oder anderer Kräfte über den Handgriff eine ausreichende Steifigkeit des Griffkörpers erforderlich.

The invention is based on the finding that in the case of a design of a handle in accordance with the prior art mentioned at the outset, a conflict of objectives is to be solved:

• On the one hand an adaptability of the grip body to the individual hand shape and size of a user and, moreover, an enlargement of the contact surface between hand and grip surface, is achieved when the rigidity of the material forming the grip body is reduced,
• - On the other hand, a sufficient stiffness of the handle body is required for a transmission of higher torques or other forces on the handle.

This Target conflict is according to the invention solved by a stiffness optimization of the grip body. According to the invention the handle body in the zone enclosed by hand when using the tool is, in the radial direction substantially three cross-sectional areas with different stiffness according to the following description: To get a hard core grip, generally made of hard plastic, as well made of metal, the first cross-sectional area, in or on which the tool anchored are a second and third cross-sectional area formed of elastic plastic, which together have a greater thickness have as the coat of soft plastic in the known handle designs. The second and third cross-sectional area is constructed so that a layer of elastic plastic adjoins the core handle, which a low hardness has and is very elasticnachgiebig. This layer is called second cross-sectional area defined. The surface layer The handle is defined as a third cross-sectional area and consists also made of elastic plastic whose hardness is higher than that of the plastic in the second cross-sectional area. In the second Cross-sectional area, the plastic can be a porous or closed structure to have. In the third cross-sectional area, the plastic is preferably a closed structure. The first cross-sectional area points a first rigidity, the second cross-sectional area a second stiffness and the third cross-sectional area a third Rigidity. The second and third cross-sectional areas are interconnected and preferably materially connected to the core handle. In addition - or too alone - can the Connection with the core handle also positively by notches in the Core grip or at this radially scheduled ribs or a non-round Cross section of the core handle be formed. In an advantageous embodiment is right on the surface of the core handle on a layer formed from the same plastic is, from which the surface layer is formed. This layer, which adjoins the core handle, has a closed structure. This layer closes in this version then the second and third cross-sectional area.

at be the application of the handle by manual force of the user according to experience by the Fingers higher normal forces exercised as through the palm of your hand. Due to the low hardness of the second cross-sectional area can this together with the surface layer according to those in different zones of the handle strong-acting normal forces give way differently. Seen in cross-section, the handle is by the finger on the side where the fingers are touching, radially pressed in, against arched out more in the direction of the force of the fingers, also towards the palm, there is a certain repression the volume of the second cross-sectional area from the finger side done in the other directions. The assumed form is broad the cavity, as formed by the fingers surrounding the handle and the palm of the hand will be adapted. By the spatial Deformation forms in the handle according to the invention a larger contact surface between Hand and grip as if the adjustment would not be made, which in the case of prior art handles. This will the specific pressure load of the hand evenly distributed, it arises no unpleasant pressure points and the applied forces can with less muscle tension can be initiated. All in all an optimal coupling of grip and hand is achieved and it creates a much more comfortable gripping feeling than with known handles - and that at different sizes or differently designed hands. As a result the elasticity the plastics used forms the original one Handle shape immediately back, when there is no force on the grip.

For the second and third cross-sectional area are preferably thermoplastic Elastomeric (TPE) plastics such as Thermoplastic Polyurethane (TPU), Thermoplastic polyolefins (TPO), polypropylene, EPDM rubber, Styrene block copolymers used. The different stiffness The cross-sectional areas are mainly by using Plastics with different hardness achieved. By adding a propellant can in the plastic of the second cross-sectional area a porous one Structure and thereby a lower rigidity are generated. For the second cross-sectional area is a very soft plastic with a hardness from 10 to 55 Shore A used for the third grip area Plastic with a hardness from 30 to 105 Shore A, especially from 30 to 85 Shore A. Will the second cross-sectional area can be made with a porous structure the plastic is a higher one initial hardness have, for example, from -20 up to 85 Shore A.

The Manufacture of the handle is done so that first the core handle in one first injection mold is made, wherein also cast the shank of the tool becomes. When hammering the shaft itself, for example made of fiber-reinforced plastic, Steel pipe or wood, form the core handle. In a second injection mold is the second and third cross-sectional area on the inserted in the mold Core handle sprayed, especially in a sandwich process.

The Manufacturing process is controlled so that the desired Thicknesses of the layers in the second and third cross-sectional areas and the one on the surface the core grip adjacent layer can be achieved, for example by the dosage amounts of one or the other injected Plastic or by the variable parameters of the injection molding process. The thicknesses of the layers are chosen in any case so that on the one hand the radial deformability of the second and third cross-sectional area upon application of a force by the hand surrounding the handle while working is not diminished, on the other hand, a good transfer an initiated torque is ensured, as it is for example when using such a handle for a tool or a screwdriver is required. It was found that a thickness of the surface layer of about 0.5 to 4 mm, for example. 2.5 mm, is expedient, wherein the thickness in Course of the surface can vary.

The Thickness, the radial extent of the layer in the second cross-sectional area is generally greater than in the third cross-sectional area, especially in the grip zones outside the smallest handle thickness and width. It was found that here in the second cross-sectional area a layer thickness of at least 3.5 mm is appropriate. In the area of the smallest thickness and width, the second cross-sectional area can be absence. Here are hardly any radial forces when using the handle In particular, only the tips of the thumb and forefinger lead the way.

The greatest deformability the handle has of course there, where the thickness of the second and third cross-sectional areas is greatest, in the place of the largest handle diameter or the largest grip thickness. Here and lie in the zone on either side of the location of the largest handle diameter the middle and ring fingers as well as the palm substantially, in In this zone, the largest and finger forces on the handle. It has been found advantageous if the ratio of largest grip diameter D or the handle thickness to the diameter d of the core handle greater than 1.4 is, in particular greater than 1.8.

For handles for other tools, as in EP 00 907 448.5 and EP 01 915 000.2 are described, the cross-sectional profiles over the longitudinal extent of the handle are not substantially round, as in a screwdriver handle, but also different in their area. With such handles, the core grip is expediently kept substantially constant in its cross-sectional area over the longitudinal extent. According to the handles EP 00 907 448.5 and EP 01 915 000.2 The largest cross-section with the largest surface is in the middle zone of the handle, so the soft plastic jacket has its largest thickness and greatest deformability. In this zone, the fingers and palm are in turn substantially, so that the desired effect of an optimal adjustment of the handle to the individual hand size and shape is achieved by the elasticity of the shell, or the second grip area.

The higher hardness of the plastic used for the surface layer or the third cross-sectional area also has the advantage that on the use of the handle foreign particles, such as metal chips, do not get stuck and can cause injury to the hand. The higher hardness also gives a more pleasant haptic feel than the surface of a very soft plastic. For the surface layer, a quality or plastic type is advantageously used, which has a sufficient resistance to chemicals, fats and oils for the application. Such resistance does not usually have the very soft plastic types used for the second cross-sectional area, or a corresponding equipment makes the plastic more expensive, so that it is also cost green it is expedient to use only for the surface layer of a plastic with appropriate resistance. Of course, however, a soft plastic with resistance to chemicals, fats and oils can also be used for the second cross-sectional area.

Advantageous is that over one on the surface the core grip fitting layer of plastic with the higher hardness, from the surface layer is formed, a torque or other forces better from the surface of the Handle can be introduced into the core handle, as if the soft plastic the second cross-sectional area would connect directly to the core handle. When Improvement of transferability Torque can, especially with handles for screwdrivers, be provided, the radially attached to the core grip ribs on the described layer of plastic higher hardness to continue to stand out let it soften in the second cross-sectional area Protruding plastic, but only so far that the radial Deformability not impaired becomes.

It was considered to further improve the portability of a torque found, the manufacturing process of the handle during injection molding, eg. by designing the molding system and / or by controlling the injection molding parameters, to control so that at least one, better two, web-like connections of the applied to the core handle layer of higher hardness plastic through the second cross-sectional area to the surface layer arises and the web-like connections at least over one Part of the longitudinal extension form the handle, especially in the zone in which substantially palm and fingers against the handle. These web-like connections support the transmission of circumferentially acting forces of the surface layer be initiated into the core grip. Although it is at these junctions between surface layer and core grip the radial deformability lower than in the other Zones, however, the elastic deformability of the handle is characterized not significantly affected.

The Mating the for the second and third cross-sectional area used plastics in hardness and Type or Type, is chosen so that on the one hand a good material connection with each other and with the core handle, to the other the desired Deformability guaranteed is.

In an alternative manufacturing method, the second and third cross-sectional area is made as a self-contained injection molded part having the same structure as described above. In this case, a central, longitudinally extending cavity is formed by a mold core having a non-circular cross-section, for example, a hexagonal cross-section or a round cross-section with molded, running in the longitudinal direction pockets. Formed around the mandrel, as in the previously described method around the core grip, is a layer of plastic with the higher hardness. The core handle has the same cross section, ie either a hexagonal cross section or a round cross section with radially mounted webs which engage in the pockets in the second or third cross sectional area. About the non-circular cross sections, a torque can be transmitted. The mass and tolerances of the two cross-sections are coordinated so that the second and third cross-sectional area forming injection molded part can be pushed fit to the core handle. Conveniently, both parts are additionally glued together. But you can also be connected by a snap connection. In the example according to 2 the snap connection consists of an annular groove molded into the core handle into which the grip part, consisting of grip area 2 and 3, engages with an annular bead. Since the handle part is made of elastic plastic, it can yield during demolding so that the annular bead lifts out of a corresponding recess in the cavity forming the cavity. Likewise, it can yield to the core handle when sliding on until the snap-in connection engages. Of course, the snap connection may also be formed in other ways, or an axial security of another kind may be provided.

at a third method of preparation, as in the first method of production, first the core handle made in a first injection mold. In a second injection mold the second cross-sectional area is placed on the in this form Kerngriff aufgespritzt and in a third injection mold of the third cross-sectional area on the inserted into this form core handle with the sprayed second cross-sectional area. The second and third cross-sectional area is thus in two consecutive, separate spraying operations sprayed on the core handle and not in one, as in the sandwich method.

The thickness of the third cross-sectional area is usually made larger in a handle made in this way than in a handle manufactured according to the first manufacturing method. At the location of the largest handle diameter or gripping thickness / gripping width, the thickness of the third cross-sectional area may be about 60 to 100% of the thickness of the second cross-sectional area. In the course of the longitudinal extension of Handle can change the thickness ratios. The hardness of the plastic used for the third cross-sectional area is expediently chosen to be somewhat lower than for a handle produced according to the first method of manufacture. For better transmission of circumferentially acting forces is advantageously provided that, starting from the circumference of the core handle, extend in the radial direction ribs in the second cross-sectional area, as well as in the handle manufactured according to the first manufacturing method.

at another embodiment the core grip extends radially to the surface of the handle approaches in the form of ribs. At least four ribs are over the Scope of the core handle distributed. Its upper edge runs in the longitudinal direction essentially the outer contour of the handle, however, faces pillow-like bulges the second and third cross-sectional area back. The pillow-like bulges can deform radially elastically under the action of a manual force and in this way adjust the hand that encompasses the handle. This Handle is manufactured in the third production method.

One special aspect of the invention is devoted to the design and capture the stiffness of the handle in the radial direction. A suitable Rigidity of the handle in the radial direction is more crucial Meaning of the feel of the handle. Furthermore, by an elasticity of the handle an adaptation to different sizes and circumstances of hands of one User done. about a design of stiffness, u. Even different in Circumferential direction of the grip, the required muscle tension be minimized, which is required to have an effect on the Exercise tool. For a screwdriver handle with center symmetrical cross-sectional contour becomes asymmetric due to the elastic deformation upon operation of the tool of the handle generated when gripping from gripping position to Gripping position changed and a very cheap one Haptic ensured.

Regarding the Design of the stiffness is the state of the art throughout the Away, with elastic zones and / or layers of the handle one Plastic according to the Shore hardness specified by the manufacturer To select A what is assumed that the specification of the material with the selected one Shore hardness A and the layer thickness of this elastic material, the rigidity of the end product "handle" is specified. On such according to the state known in the art handles, such as screwdrivers, can in Area of the lateral surface of the handle a determination of hardness Shore A with one in itself known Shore hardness tester done.

In the Internet encyclopedia Wikipedia is under the entry "hardness" on 02.03.2007 to hardness Shore executed that this is a material characteristic value for Elastomers and plastics, which in the standards DIN 53505 and DIN 7868. The core of the Shore hardness tester is from a spring-loaded pin made of hardened steel. The penetration depth in the to be tested Material is a measure of the corresponding Shore hardness that on a scale from 0 Shore (2.5 mm penetration) to 100 Shore (0 mm penetration depth) is measured. A high number means so a big Hardness. The material thickness should be at least 9 mm in the range of 0-50 Shore, with harder ones Substances at least 6 mm. For the measurement Shore A is done using a pin with blunted Top. The face the truncated cone in the area of the tip has a diameter of 0.79 mm and the opening angle is 35 °.

The Applicant has recognized that the determination of the hardness Shore A for the determination of the relevant rigidity of the handles present here (alone) are insufficient. This is due to the fact that in known Shore hardness testers, the elastically supported pin is laterally surrounded by a reference surface. The hardness tester is then applied to the specimen with a contact force until the reference surface contacts the specimen. If, however, the test specimen has a relatively soft intermediate layer under the outer layer interacting with the test device, a force can be exerted during the Shore hardness test by the pin and / or the reference surface which also leads to deformations of this soft intermediate layer, which causes movement of the with the tester interacting outer layer has the consequence. Thus, although the Shore hardness tester determines a characteristic hardness value. However, this is smaller than the hardness value of the plastic used for the outer layer. Not sufficiently measured is the radial total rigidity of the handle, for which the hardness of the plastic used for the outer layer is merely an influencing factor. The measuring method described in the present application captures the entire radial deformability better, because it includes a larger area of the handle cross-section, namely the entire radial extent of the handle in cross section, in the measurement. In other words, the Applicant has observed that hardness of a cladding layer of the handle that is high but has a small layer thickness, with soft support of the cladding layer for the user, can lead to the same appreciable radial stiffness as a softer cladding layer that is made thicker and / or slightly harder supported. For the abovementioned variants, hardness testing according to Shore (alone) can lead to hardnesses which do not describe ergonomics, while according to the invention a characteristic size is obtained is intended to represent the actually experienced for the user of the handle stiffness and ergonomics.

• – Zunächst wird der Griff weitestgehend ohne Last eingespannt zwischen einer Anlagefläche, beispielsweise einem Tisch, und einem Prüfkopf. Infolge der Einspannung ergeben sich zwei Kontaktflächen auf der Mantelfläche des Griffes, vorzugsweise im Bereich des größten Durchmessers des Griffes. Die beiden vorgenannten Kontaktflächen liegen sich ungefähr diametral auf der Mantelfläche des Griffes gegenüber. Durch das weitestgehend belastungsfreie Einspannen kann ein Referenzabstand der Kontaktflächen vorgegeben werden (gleiches könnte auch durch Einspannen mit einer vorgegebenen Einspannkraft erfolgen, die kleiner ist als die später genannte definierte Anpresskraft). Der Prüfkopf ist im Bereich der Kontaktfläche vorzugsweise kugelförmig ausgebildet, wobei ein Durchmesser 8 mm betragen kann.
• – Anschließend wird eine definierte Anpresskraft des Prüfkopfes auf die Mantelfläche des Griffes in radialer Richtung des Griffes aufgebracht, wobei diese Anpresskraft vorzugsweise 30 Newton beträgt.
• – Schließlich wird ein sich infolge der definierten Anpresskraft ergebender veränderter Abstand zwischen der Anlagefläche und dem Prüfkopf ermittelt.

According to the invention, the following test method is proposed:

• - First, the handle is largely clamped without load between a contact surface, such as a table, and a probe. As a result of the clamping, there are two contact surfaces on the lateral surface of the handle, preferably in the region of the largest diameter of the handle. The two aforementioned contact surfaces are approximately diametrically opposite to the lateral surface of the handle. By largely stress-free clamping a reference distance of the contact surfaces can be specified (the same could also be done by clamping with a predetermined clamping force, which is smaller than the defined defined contact force). The probe is preferably spherical in the area of the contact surface, wherein a diameter may be 8 mm.
• - Subsequently, a defined contact force of the probe is applied to the lateral surface of the handle in the radial direction of the handle, said contact pressure is preferably 30 Newtons.
• - Finally, a resulting due to the defined contact force changed distance between the contact surface and the probe is determined.

With the resulting changed Distance is thus an "integral" measure for everyone Deformations over given the entire diameter of the handle, which previously not has been recorded.

According to one first embodiment of the invention, the aforementioned changed distance between 2.5 and 7 mm, for example between 3 and 6 mm (or 3.0 and 5.5 mm or 3.5 and 5 mm) for a handle whose unloaded Diameter between 25 and 40 mm, for example 30 to 40 mm or 33 to 37 mm, in the region of its largest diameter.

Corresponding Another proposal of the invention is the cross section of the handle in first proximity circular or in the form of a polygon, in particular a triangle, Quadrilaterals, pentagons, Hexagons or octagons, formed, with this cross section in first approximation with straight flanks and rounded or flattened corners formed is. According to the invention radial stiffness in the area of the corners smaller than in the area the flanks, allowing a deformation of the corner areas by hand the user is simplified, what u. U. for the user as pleasant is felt. On the other hand u. U. increased in the corners normal forces and thus also frictional forces be generated, which is a transmission a big one operating torque enable.

Corresponding a development of a handle according to the invention is due to of the previously explained test method changed Distance of the handle in the area of the corners by 2 to 30%, especially 2.5 up to 6% larger than in the area of the flanks. Such a stiffness ratio be advantageous in terms of transferable moments and the Ergonomics of the handle exposed.

In different sizes can Handles also in sentences used by hand or garden tools, especially when These are tools of various sizes, such as screwdriver sets, or Gardening equipment sets with different sizes. Handles with the structure described are suitable for tools, with which an actuating torque around a longitudinal axis of the handle should be like screwdrivers, screw clamps, but for example also for saws, Trowels, hammers, Chisels, tongs, garden tools, knives and other tools, the outer shape the one for the respective tool appropriate form equivalent.

advantageous Further developments of the invention will become apparent from the claims, the Description and the drawings. The in the introduction to the description advantages of features and combinations of several Features are merely exemplary and may be alternative or cumulative come into effect, without the benefits of mandatory embodiments of the invention must be achieved. Other features are the drawings - in particular the illustrated Geometries and the relative dimensions of several components to each other as well as their relative arrangement and operative connection - can be seen. The combination of features of different embodiments the invention or features of different claims also different from the selected ones Relationships of the claims possible and is hereby stimulated. This also applies to such features are shown in separate drawings or in their description to be named. These features can be combined with features of different claims. As well can in the claims listed features for further embodiments the invention omitted.

SUMMARY THE FIGURES

In the drawings of the subject invention is exemplified. Show it:

1 a longitudinal section through a handle according to the invention for a screwdriver with the spherical end of the handle forming cap, which is integrally formed at one end of a core handle, with a cutting guide according to II in 3 , wherein in the upper half-plane the section is guided by a web-like connection and not in the lower half;

2 a cross section through a handle according to 1 with cut according to III-III, but deviating from 1 and 3 no web-like connection is provided;

3 a cross section through a handle according to 1 with a cutting guide according to III-III in the embodiment with web-like connection between a layer adjacent to the core grip and an outer layer;

4 a longitudinal section through a handle which is axially secured with a second and third cross-sectional area by a snap connection on a first cross-sectional area forming core handle;

5 a longitudinal section through a handle, in which a core handle is extended in a front part to a grip surface and a second and third cross-sectional area between the front part of the core handle and a reduced cap is taken;

6 a longitudinal section through a handle in which a first cross-sectional area forming core handle does not go to one end of the handle, but wherein the end of the handle is formed by a second and third cross-sectional area;

7 a longitudinal section of a handle, in which a shaft of a core handle without cap passes to the rear end of the handle;

8th a longitudinal section of a handle, which is made with a manufacturing process referred to as a third manufacturing method, when cut along the line IIX-IIX according to 9 ;

9 a cross section through the handle according to 8th when cutting according to line IX-IX;

10 a longitudinal section through a handle, which is made with a manufacturing process referred to as the fourth manufacturing method, when cut along line XX in 11 ;

11 a cross section through the handle according to 10 when cut along line XI-XI;

12 a perspective view of the handle according to 10 and 11 ;

13 a device for testing the radial total stiffness of a handle of a screwdriver in a schematic representation;

14 a detail XIV for the contact area for a test head with a lateral surface of the handle for the device according to 13 wherein the applied contact force is about 0;

15 a detail XV for the contact area for a test head with a lateral surface of the handle for the device according to 13 , wherein the required contact force of the test head is applied to the lateral surface of the handle.

DESCRIPTION OF THE FIGURES

The longitudinal section according to 1 through a handle 1 shows a core grip 3 made of hard plastic, which forms a first cross-sectional area and defines a first stiffness. Inserted into the core handle is a shaft 2 a tool. At the end of the core handle is a large cap 4 formed on the core handle and forms the crowned end of the handle 1 , The cap 4 Made of hard plastic has a smooth, low-friction surface. This is advantageous in a screwdriver handle, because when exercising a high torque, the hand at the end of the handle 1 supports and the handle 1 turns in the palm of your hand. For smaller handles or such for other tools with a different hand-grip coupling, the formation of such a cap is not required. A surface layer 5a covers essentially the entire surface of the handle 1 except for the cap 4 and / or an extended front part 3a of the core grip 3 at the front end of the handle 1 , At the front or on the front part 3a as well as with the surface of the cap 4 lies the core grip 3 during manufacture sealing in a mold cavity, when a second and third cross-sectional area 5b . 5a on the core handle 3 be sprayed, for example in a sandwich process. The front part may also be shorter in its longitudinal direction than in 4 is shown.

The surface layer 5a forms a third cross-sectional area with a third stiffness. The surface layer usually sits on the inside of the cap, the inside of the front part 3a and in the range of the smallest handle diameter - if it is small in diameter even in the absolute measure - to the surface of the core handle 3 and forms adjacent to the core handle 3 the layer 5c , A connection between the surface layer 5a and the layer 5c along the inside of the cap 4 But it does not have to be there. Rather, a connection can also take place elsewhere or not exist at all. Between the surface of the core handle 3 or the layer 5c is the second cross-sectional area 5b which has a second rigidity. The second and third cross-sectional areas are formed of elastic plastic with different hardnesses, wherein the plastic used for the third cross-sectional area has a higher hardness than the plastic used for the second cross-sectional area. Upon application of the tool to the handle with a hand force, the third and second cross-sectional areas deform spatially and conform to the cavity of the finger and palm acting on the handle to provide optimum grip and hand coupling.

The three cross-sectional areas are - by appropriate selection of the plastics used - material by welding during the injection process, connected to each other. In addition - especially with handles with which a torque must be transmitted - a positive connection of the first and second cross-sectional area can be provided. In the example of 1 are ribs 6 radially to the core handle 3 set that still over the layer 5c projecting out into the second cross-sectional area. It is advantageous that the layer 5c is formed between the ribs. Since it has a higher hardness or strength than that of the second cross-sectional area 5b forming plastic and with the surface of the core handle 3 is connected by welding, it contributes effectively to the transmission of torque.

By 2 a possible cross-section of a handle is shown, but deviating from the 1 and 3 ribs 6 not continuously formed to the surface layer.

In 3 are two web-like connections 5d made of plastic of higher hardness of the layer 5c at the core handle 3 to the surface layer 5a to recognize these compounds through the second cross-sectional area 5b pass.

Notwithstanding the in 3 illustrated cross section, it is possible that the thickness of the surface layer 5a varies, for example in the area of edges or corners 43 is greater than in the area of flanks 44 of the polygonal outer cross-section to a first approximation. Furthermore, it is different or complementary to the in 3 illustrated vertical orientation of the ribs 5d possible that these in alignment according to the cross section in 3 are oriented horizontally, which has the consequence that the ribs are not as in 3 shown in the range of corners 43 in the cladding layer 5a but rather approximately in the middle of flanks 44 ,

4 shows in longitudinal section a handle, which is manufactured according to the second manufacturing method. The second and third cross-sectional area 5b . 5a are manufactured in an injection mold as a separate part, which results in the same layering as when spraying on the core handle according to the embodiments according to 1 to 3 , Through this part extends in the longitudinal direction, however, a cavity whose cross-sectional contour of the selected cross-sectional contour of the core handle 3 corresponds and which is formed during injection molding by a mandrel. To protect against rotation, or for the transmission of torque, the cross-sectional contour is out of round. In the example are to the core handle 3 ribs 6 stated. In the separately produced handle part are formed radially from the longitudinally extending cavity outgoing pockets into which the ribs engage when the part from the front of the core handle 3 is plugged. In the end position, the grip part lies with the rear end on the inside of the cap 4 at. At the front end it is by a snap connection 7 with the core handle 3 connected and secured in its axial position.

• – entweder zunächst als eigenes Spritzgießteil gefertigt und von hinten über die Kappe 4a auf den Kerngriff aufgesteckt werden,
• – oder es wird direkt auf den Kerngriff aufgespritzt, wie bei der Ausführung gemäß 1.

In the embodiment also shown in longitudinal section according to 5 is the front part 3a of the core grip 3 expanded in the radial direction and forms with its surface the front portion of the handle surface. The cross-sectional areas 5b . 5a lie between the extended front part of the core handle and a - reduced - cap 4a at the end of the core grip. The grip part with the cross-sectional areas 5a . 5b can

• - either initially manufactured as a separate injection molded part and from the back over the cap 4a be plugged on the core handle,
• - Or it is sprayed directly on the core handle, as in the execution according to 1 ,

Because the cross-sectional areas 5a . 5b are elastic, extending in the longitudinal direction cavity during assembly of the injection molded part on the reduced diameter cap 4a , In the end position, the part is firmly on the core handle 3 and is axially between the extended front and the cap at the end of the core handle 3 secured.

6 shows in longitudinal section finally a handle in which the core handle 3 not until the end of the handle 1 passes. Rather, his end is 3b opposite the rear end of the handle 1 back, and where the end part 8th the handle made of plastic of the cross-sectional areas 5a 5b is formed. It is possible that the core grip only with the extended front part 3a sealingly abuts in the mold cavity and the cross-sectional areas 5a . 5b be sprayed onto the protruding into the mold cavity part of the core handle.

7 shows a partial longitudinal section of a handle, in which the shaft 3c the core handle without cap to the rear end of the handle 1 goes through, wherein the end surface sealingly abut the mold cavity.

8th shows in longitudinal section along the line IIX-IIX in 9 a handle 1 in a third way of production. It can be seen that the thickness or the radial extent of the surface layer 5a of the third cross-sectional area is larger than in the handle manufactured in the first manufacturing method according to 1 while the thickness of the second cross-sectional area 5b smaller than the handle according to 1 , This is also in the 9 clearly in the representation of a cross-section with a section along the line IX-IX in

8th , The thickness of the third cross-sectional area is, depending on the handle size, between 2 and 7 mm.

In 10 is a handle 17 a further embodiment in a longitudinal section with a section along the line XX through the radially extending webs 18 in 11 shown. The bridges 18 extend to the surface of the handle. They are surmounted by the surface contour of the pillow-like protruding bulges 19 the surface layer 5a , This is also in 11 to see which has a cross-section when cut along the line XI-XI in 10 represents.

The same reference numerals have been used in the different figures for parts which are identical in function or arrangement. Further use can the 1 to 12 corresponding handles for garden tools, trowels, hammers and similar tools, in particular those with which a torque must be transmitted, wherein other geometries of the handle and / or the layers, but an identical or similar structure can be used.

13 shows a device 30 for testing a resulting overall stiffness of a handle 1 . 17 in the radial direction. The device 30 has a contact surface 31 on which the handle 1 . 17 rests. This is where the handle is based 1 . 17 exclusively or mainly at a contact surface 32 off, from the outer surface 33 the handle is formed. In a carrying unit 34 is displaceable in the vertical direction with minimal friction as a measuring element 35 guided. The measuring organ 35 has a measuring head 36 that is rigid with guide rods 37 facing the measuring organ 35 are guided in the vertical direction, and a weight 38 is coupled. A displacement of the measuring head in the vertical direction is provided by a sensor 39 , For example, a dial gauge detected. It is possible that the weight 38 is changeable, for example by removing or supplementing partial weights.

As in 14 can be seen, has the measuring head 36 a contact body 40 for the illustrated embodiment with a ball or part ball 41 is formed. It is possible that in the measuring head 36 different contact bodies 40 with different geometries, surfaces, cross-sections and curvatures in the contact area with the handle 1 . 17 can be kept interchangeable. In the case of the use of a ball 41 as a contact body 40 This results in a kind of Hertzian contact between the measuring head 36 and the handle 1 . 17 ,

For a determination of the stiffness of the total grip in the radial direction is corresponding 13 a handle 1 . 17 on the contact surface 31 for what the measuring organ 35 is lifted vertically. An orientation of the handle 1 . 17 takes place such that the peripheral region of the lateral surface 33 , on the basis of which a radial rigidity is to be determined, on the contact surface 31 rests. Such alignment may be manual or automated, for example with a stepper motor to effect rotation of the screwdriver. Is the desired orientation of the screwdriver and the handle 1 . 17 reached, the measuring organ 35 lowered until the measuring head 36 in the area of a contact surface 42 for contact with the lateral surface 33 of the handle 1 . 17 what's coming in 14 is shown. 14 shows here a concern of the measuring head 36 with vanishing power.

With release of the weight of the weight 38 it comes to a deformation of the handle 1 . 17 in the radial direction, reflecting in 15 is shown schematically. In this case, the contact force exerted by the weight force acts as a compressive stress in the range of the diameter, which the contact surface 42 of the measuring head 36 with the lateral surface of the handle 1 . 17 with the contact surface 32 of the handle 1 . 17 with the contact surface 31 combines. The aforementioned compressive stresses lead to a deformation over the aforementioned diameter. The deformations in the area of the diameter, ie individual deformations of the individual layers present in the handle, accumulate to a total displacement, which over the sensor 39 or the dial gauge is detected.

According to an exemplary embodiment, which has been used for the measurements listed in the application, the ball has a diameter of 8 mm. The weight 38 (and other associated mitbewegte components) has a total weight of 3 kg.

The investigations carried out have handles according to the invention 1 . 17 shown that deformations, ie changes in the distance ΔD of the contact surface 42 of the measuring head 36 with the lateral surface 33 of the handle 1 . 17 and the contact surface 32 hereinafter referred to as D _V (diameter before application of the weight) and D _N (diameter after application of the weight) are given as follows: ΔD = D V + D N with ΔD in the range of 2.5 to 7 mm, in particular 3 to 5.5 mm.

Specifically, defining a degree of deformability G = ΔD / D _V gives values of G in the range of 8.5% ± 2% for handles with large grip diameters (maximum diameters of 33 to 40 mm) while one degree G is in the range of 20% ± 5% for handles with small handle diameters (maximum diameters of 25 to 33 mm).

In the region of the largest handle diameter results on the surface of the handle, but outside of a stiffened by radial webs zone, a measured hardness Shore A between 20 and 40%, in particular between 25 and 38%. The measuring method based on the in 13 illustrated device 30 refers to a conventional measurement of a hardness Shore A a larger range of grip surface in the measurement. Furthermore, a measurement is made with a larger force due to the weight 38 as in a conventional hardness measurement Shore A.

The following table shows exemplary test results for different test methods and different handles, the length L being the total length of the handle and the diameter ∅ denoting the diameter of the handle on the largest hand-held portion of the handle. The first and second group of samples has a handle construction according to 3 , The samples shown in the third group, however, have a structure accordingly 8th and 9 with a relatively thick shell layer. For several samples of the same construction, different measurement results are listed in the respective rows. For the respective samples, the material hardness of the plastic used for the inner layer and the outer layer in hardness Shore A is given first. The following two columns show the deformation determined by the test method proposed here, ie ΔD, once in the middle of the flank of the handle 44 and once in the area of a corner 43 ,

This is contrasted with the determined hardness Shore A in the area of the flank / corner in the following columns. A supplementary measured value is given for a determination of the hardness Shore A over a web 5d ,

Other features in terms of the design of the handles and the production of the same can be found in the applications of the applicant. In particular, PCT / EP2006 / 006045 discloses a method of manufacturing a handle with a sandwich method, which leads to the formation of a core layer sheathing inner layer, an intermediate layer and an outer layer forming a lateral surface. Ribs may extend from the inner layer into the intermediate layer or may be formed throughout from the inner layer to the outer layer. Furthermore, PCT / EP 2006/010184 discloses advantageous possibilities for a design of handles, in particular in cross-section, with particular attention being paid to the design of the layer thicknesses in the circumferential direction of the handle. DE 10 2006 037 688 discloses a handle for a tool in which a web or a rib is firmly bonded to the inner surface of a cladding layer. DE 10 2006 038 636 discloses a manufacture of a handle using a PUR process wherein base components of the handle or film forming plastic react in a mold with a blowing agent. DE 10 2006 061 068 discloses the provision of volume change chambers for foaming the propellant-provided plastic during the manufacture of the handle. Such volume change spaces may be created, for example, by opening a mold or inserting the handle or a component thereof prior to final curing of the layer or handle forming material. Finally beats DE 10 2005 055 981 the formation of the handle with radial, cushion-like elastic bulges to improve the ergonomics of the handle. The aforementioned aspects of the applicant's patent applications can be easily integrated into the embodiments according to the present invention.

1

Screwdriver handle

2

shaft

3

core handle (first cross-sectional area)

3a

expanded Front part of the core handle

3b

The End the core handle without cap

3c

shaft of the core grip

4

big cap at the end of the core grip

4a

reduced Cap at the end of the core handle

5a

surface layer (third cross section area)

5b

second Cross section area made of very soft plastic

5c

the on the core handle fitting layer of the same plastic, from the surface layer is formed is

5d

web-like links

6

at the Core grip radially attached ribs

7

snap

8th

the formed from the second and third cross-sectional area end portion of the handle

17

one Handle of the fourth embodiment

18

radial down to the surface extending ribs

19

cushiony bulges of the second and third cross-sectional areas

30

contraption

31

contact surface

32

contact area

33

lateral surface

34

support unit

35

measuring element

36

probe

37

guide rod

38

Weight

39

sensor

40

Contact body

41

Bullet

42

contact area

43

corner

44

flank

D1, D2

of the largest diameter or the biggest thickness of the handle

d1 d2

of the Diameter or height / thickness of the core grip

Claims (39)

Handle ( 1 . 10 ) For a tool, in particular for a screwdriver, which is constructed in the zone, which is enclosed by use of the tool by hand, in the radial direction substantially of three cross-sectional areas with different stiffness, namely a) a first cross-sectional area, which with a Core grip ( 3 . 12 ) is formed of a hard material having a first rigidity, b) a third cross-sectional area which is provided with a surface layer ( 5a ) made of elastic plastic with a third stiffness and c) a lying between the first and third cross-sectional area second cross-sectional area ( 5b ) of soft elastic plastic having a second stiffness, d) the second stiffness being less than the third stiffness, and the dimensioning of the regions and their rigidity being such that when the grip is acted upon ( 1 . 10 ) by the force of a hand deformation of the second and third cross-sectional area ( 5a . 5b ), characterized in that e) the thickness of the third cross-sectional area ( 5a ), measured at the location of the largest handle diameter or the largest thickness / width, 60 to 100% of the thickness of the second cross-sectional area. Handle according to claim 1, characterized that the thickness of the third cross-sectional area over the longitudinal extension of the handle is substantially constant. Handle according to claim 1 or 2, characterized that the handle is manufactured using a two-stage manufacturing process in which, in a first stage, the second cross-sectional area in a first form is sprayed on the core handle and in a second stage of the third cross-sectional area in a second form sprayed on the core handle. Handle according to one of the preceding claims, characterized in that the ratio of the largest diameter or the greatest thickness D1, D2 of the handle ( 1 . 9 . 15 ) to the diameter d1, d2 of the core grip ( 3 . 16 ) is greater than 1.4, in particular greater than 1.8. Handle according to one of claims 1 to 4, characterized in that the plastic in the second cross-sectional area ( 5b ) has a closed structure and a hardness of 10 to 55 Shore A. Handle according to one of claims 1 to 4, characterized in that the plastic in the second cross-sectional area ( 5b ) has a porous structure and a hardness of 20 to 85 Shore A in the starting material. Handle according to one of claims 1 to 6, characterized in that the plastic in the third cross-sectional area ( 5a ) has a hardness of 30 to 105 Shore A. Handle according to claim 7, characterized in that the plastic in the third cross-sectional area ( 5a ) has a hardness of 30 to 85 Shore A. Handle according to one of claims 1 to 8, characterized in that the hardness of the plastic in the third cross-sectional area ( 5a ) is greater than the hardness of the plastic in the second cross-sectional area ( 5b ). Handle according to one of claims 1 to 9, characterized in that the radial extent or the thickness of the second cross-sectional area ( 5b ) is on average larger than that of the third cross-sectional area ( 5a ). Handle according to one of claims 1 to 10, characterized in that the plastic in the third cross-sectional area ( 5a ) has no porous structure. Handle according to one of claims 1 to 11, characterized in that the plastic at least in the third cross-sectional area ( 5a ) has sufficient resistance to oils, greases and chemicals. Handle according to one of claims 1 to 12, characterized in that the thickness of the third cross-sectional area ( 5a ) is between 0.5 and 2.5 mm or 0.5 and 4 mm. Handle according to one of claims 1 to 13, characterized in that around the core handle ( 3 . 12 ) a layer ( 5c ) is formed, which is formed from the same plastic as the third cross-sectional area ( 5a ). Handle according to one of claims 1 to 14, characterized in that the second and third cross-sectional area ( 5b . 5a ) are materially interconnected. Handle according to one of claims 1 to 15, characterized in that the first cross-sectional area ( 3 . 12 ) and second cross-sectional area ( 5b ) are materially and / or positively connected with each other. Handle according to one of claims 1 to 16, characterized in that the second and third cross-sectional area ( 5b . 5a ) directly on the core cross-section forming the first cross-sectional area ( 3 . 12 ), in particular in a sandwich process. Handle according to one of claims 1 to 17, characterized in that the second and third cross-sectional area ( 5b . 5a ) manufactured as an injection molded part and on the core handle ( 3 . 12 ) forming the first cross-sectional area, positively connected thereto and by gluing or a snap connection ( 7 ) are attached to it. Handle according to one of claims 1 to 18, characterized in that the core handle ( 3 ) one the crowned end of the handle ( 1 ) forming cap ( 4 ) whose diameter is greater than the diameter of the shaft ( 3c ) of the core grip. Handle according to claim 1 to 19, characterized in that the core handle ( 3 ) no crowned cap ( 4 ) and with the shaft ( 3c ) to the end of the handle ( 1 goes through). Handle according to one of claims 1 to 20, characterized in that the core handle ( 3 . 12 ) not until the end of the handle ( 1 goes through). Handle according to one of claims 1 to 21, characterized in that the second and third cross-sectional area ( 5b . 5a ) the core handle ( 3 . 12 ), with the possible exception of the cap ( 4 ) and / or the front part ( 3a ), almost completely surrounded. Handle according to one of claims 1 to 22, characterized in that the core handle in the front area ( 3a ) is enlarged radially to the handle surface and the second and third cross-sectional area ( 5b . 5a ) are formed in the substantially by the user hand included middle and rear handle portion having a length (L) of about two thirds to three quarters of the entire handle length (L). Handle according to one of claims 1 to 23, characterized in that radially on the core Handle ( 3 ) ribs ( 6 ) into the second grip area ( 5b ) extend into it. Handle according to one of claims 1 to 24, characterized in that at least one web-like connection ( 5d ), consisting of the same plastic, from which the third cross-sectional area is formed, the surface layer ( 5a ) and the around the core handle ( 3 ) trained layer ( 5c ) connects in the radial direction. Handle according to one of claims 3 to 25, when appended to claim 3, characterized in that the core grip forming the first cross-sectional area (FIG. 3 ) radially up to the surface of the handle ( 17 ) extending ribs ( 18 ) whose upper edges are clearly opposite the second and third cross-sectional areas (FIG. 5a . 5b ) formed bulges ( 19 ) stand behind. Handle according to one of claims 1 to 26, characterized in that the deformation of the second and third cross-sectional area ( 5a . 5b ) is done by the force of a hand at least in the zone in which the palm, ring and middle finger are mainly present. Handle according to one of claims 1 to 27, characterized that the handle in construction meets these requirements, but in terms of external form the for the respective tool expedient and usual Form corresponds. Handle according to one of the preceding claims, characterized in that the hardness of the plastics used and the thickness of the cross-sectional areas are selected so that the handle has a radial stiffness in the region of its largest diameter, which when tested according to the following test method: a) stress-free clamping of two contact surfaces formed by the lateral surface of the handle ( 32 . 42 ), which are diametrically opposed to the outer surface of the handle, between a contact surface ( 31 ) and a test head ( 36 ), the test head ( 36 ) in the area of the contact surface ( 42 ) is spherical with a diameter of 8 mm, b) application of a defined contact force of the test head ( 35 ) of 30 N on the lateral surface of the handle in the radial direction of the handle, c) detecting the resulting due to the defined contact pressure changed distance ΔD between the contact surface ( 31 ) and the test head ( 36 ). such is that the changed distance ΔD between 2.5 and 7 mm at a maximum diameter D _{V of} the handle is between 25 and 40 mm. Handle according to claim 29, characterized that the changed Distance ΔD between 3 and 5.5 mm. Handle according to claim 29 or 30, characterized that in the area of the largest diameter Hardness values measured on the circumference between 20 and 50 Shore A lie. Handle according to claim 31, characterized that in the area of the largest diameter at Scope measured hardness values between 25 and 45 shore A lie. Handle according to one of the preceding claims, characterized characterized in that the cross section of the handle is circular in a first approximation or a polygon, in particular a quadrangle, pentagon, hexagon or octagon with in first approximation straight flanks and rounded corners, corresponds. Handle according to claim 33, characterized that the radial stiffness in the area of the corners is smaller than in the area of the flanks. Handle according to claim 34, characterized that the changed Distance ΔD of the handle in the area of the corners is 2 to 30% larger than in the area of Flanks, in particular 2.5 to 6% larger than in the field of Flanks. Handle according to claim 33, characterized that the radial stiffness in the area of the corners is greater as in the area of the flanks. Handle according to claim 36, characterized in that the changed distance ΔD of the handle in the region of the flanks is greater by 2 to 30% than in the region of the corners, in particular 2.5 to 6% greater than in the area of the corners. Handle according to claim 33, characterized that the radial stiffness over the circumference approximately is constant, especially for a first approximation circular Cross section or cross section in the form of a polygon. Hand or garden tool set, characterized that handles according to one of claims 1 to 37 in different Sizes included are.