DE2408088A1 - IMPACT TOOL - Google Patents

Description

The Stanley Works 1 9 _C Feb. 1974

New Britain, Connecticut
United States of America

Punch tools.

The invention relates essentially to punch tools, such as hammer, ax, hatchet and similar hand tools and them relates in particular to an improved attachment of the handle to the head of the tool by that in normal conditions of use to avoid the usual loosening between the tool head and the handle in such tools. The invention is particularly advantageous for use in tools, with the handle made of non-metallic material such as wood or plastic is.

Breaking tools, such as hammers, have had one for a long time metallic tool head and non-metallic handles, and the end of the handle is in a central opening of the tool head

introduced and fastened in this. For fastening the end of the handle on the tool head it is known to have the opening in the tool head with a point in the direction of the outlet end of the opening to provide widening cross-section and the end of the stem, which is inserted through the smaller inlet end of the opening is to press firmly against the wall of the opening by wedging. This is done by hammering in one or more “wedges” reached into the exposed end of the tool handle whereby the The end of the stem is spread apart and its circumference is pressed against the opening surface. Although such fortifications closed Are very firm at the beginning, they have been known to deteriorate quickly with normal use of the tool interrupted

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loads that occur during the use of the tool, as well as other circumstances such as the occurrence of cracks in the end of the handle due to the wedging and the alternating Swelling and contraction of the handle due to variable humidity, all contribute to the rapid deterioration of the solid Seat at and cause a loosening and possibly a separation of the tool head from the handle.

After the development of improved adhesives and in particular Adhesives made of thermoplastic resin, such as epoxy resin, such materials were used to glue the handle in the opening of the tool head without or in connection with the usual wedging. However, it has been found that it can be used to produce an effective vibration dampening attachment of the tool head in this process, direct contact between the handle and the metal head is required to ensure along a substantial area of the opening, whereby the area available for gluing is significantly reduced. This disadvantage affects in relation to others Disadvantages of the adhesive material often break quickly or a loosening of the adhesive bond under the load, so that the handle becomes loose and moves away from the tool head without substantial Increasing the service life of the connection triggers. When attempting to use rubber or rubber-like inserts are similar Difficulty occurred.

The object of the invention is accordingly a handle attachment to create for striking tools which avoids the disadvantages mentioned above and a solid, effective connection between the tool head and the handle ensures which one has a long life before repair or replacement is required.

Another object of the invention is to provide a connection which can be easily obtained by using standing materials with consistently high quality and the application of the invention is said to be economically attractive as well as to provide improved results.

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Another object of the invention is a handle attachment to create what the desired properties of the tool such as balance and vibration damping are not adversely affected and which compound cannot deteriorate as a result of external conditions.

These objects are achieved according to the invention by that the opening in the tool head and the end of the handle have cooperating shapes, including the handle in the axial direction is provided with opposite surfaces arranged at a distance from one another, in the interior of the opening preferably at least a suitable Ke il'f lache is arranged and the stem has a circumferential groove has, and that the space between the surfaces is filled with a suitable moldable plastic, which at Hardening forms a tough, hard and strong mechanical lock in order to avoid an axial movement of the handle in relation to the tool head, whereby a firm, permanent and effective connection is achieved over a long service life.

An embodiment of the invention is shown in the drawing and is now described in more detail, it shows:

Figure 1 is a partial side view of a hammer, partially in section, to illustrate the preferred embodiment of the stem connector according to the present invention.

Figure 2 is a partial rear view taken along line 2-2 Figure 1.

Figure 3 is a plan view of the hammer according to Figures 1 and 2, but without the locking piece made of plastic.

Reference is now made to the drawings, wherein the invention is illustrated by means of a hammer which has a hammer head IO of forged steel of the claw type, the is provided at one end with a conventional hammer track 11 and at the other end with claws 12. The hammer head 10 has a medium one Opening 13 for receiving a handle 18. The opening is a through opening with an inlet end 14 on the lower side a lug 15 and an outlet end 16 on the top surface

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of the tool head ΙΟ. In the preferred embodiment is the cross-section of the opening 13 is essentially rectangular although the teaching of the invention also applies to other cross-sectional shapes, such as for oval or round openings, can be used.

The inlet area 17 in the vicinity of the inlet end 14, which in the preferred exemplary embodiment is slightly smaller than a third of the length of the opening, has a constant cross-section or widens slightly to the inlet end 14. The inlet area 17 is in firm engagement with the end of the stem 18 if the same "is inserted from the inlet end 14. The stem is dimensioned such that it is compressed somewhat in the inlet area so that the inlet end 14 extends to form a Sealing slightly in the material of the stem impresses if the stem is fully inserted.

The cross section of the remaining area 19 of the opening 13 increases steadily in the direction of the outlet end 16. This is partly due to a slight inclination of the front surface 2o forwards and a slight inclination of the rear surface 21 backwards is achieved. Although the degree of inclination can vary from case to case, is for example in the particular embodiment shown in the drawings, the dimensions of the opening 13 from the front Area to the rear area at the outlet end about 6.35 to 4.76 mm larger than this dimension at the inlet end. In the preferred embodiment the transverse dimension of the opening 13 also increases in the direction of the outlet end because the side surfaces 22 and 23 are mutually aligned expand very slightly in the direction of the outlet end 16.

As far as has been described so far, the hammer head corresponds to IO and the formation of the opening essentially the known hammer head from guides, which are used if a common one non-metallic handle is to be attached by the usual wedging. This has the advantage that the production is carried out without significant changes to existing systems and to the currently applicable manufacturing process η for manufacturing of impact tool heads are to be carried out.

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■ - 5 -

The end region of the stem 18, which in this embodiment is a wooden handle, protrudes into the opening 13 by being inserted through the inlet end of the opening. The end of the stem 18, which is inserted into the opening, is modified in accordance with the teaching of the invention to form a head area 24 with a smaller cross-section than the area of the opening 13 in the Near the outlet end 16 and there is play between the opening. tion 13 around its entire circumference and along its length. In the preferred embodiment, the sides dfes are tapered Head part 24 inwards towards the outlet end in order to reach an optimal game. The shoulder area 24 of the stem is dimensioned to achieve a tight fit and to form a tight connection with the inlet area 17 of the opening In the vicinity of the shoulder area 25 and between this area and the head area 24 is a region 26 with a smaller one Cross-section, which according to the preferred embodiment consists of a circumference that is relatively wide and is flat and the edges are beveled. A suitable one For example, the groove would be about 6.35 mm wide and about 3.18 mm deep. These particular dimensions are only given as an example for a preferred embodiment. The invention is not limited to such dimensions since they can be changed within reasonable limits and since they also change depending on the type and size of the tool. In the preferred embodiment ends the head part 24 just below the outlet end 16 of the opening, but this is not essential and the end of the The stem can be aligned with the outlet end 16 if desired.

In accordance with the invention, the urinal space is around that End of the handle and between the handle and the opening and also the outlet end of the opening 13 if the handle is not along the entire length of the opening is filled with a tough, hard and strong plastic 27, which has a high impact resistance and has a high dimensional stability. Among the im Commercially available plastics with the physical properties required for this purpose can be mentioned, for example:

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- ο -

Polycarbonates sold under the trademark "Merlon" by Mobay Chemical Company and under the trademark "Lexan" from General Electric Company, acetals such as acetal homopolymers, those sold under the trademark "Oebrin" by E.I. duPont de Nemours & Co. Inc. and Aze ta lko polymers operating under the trademark "Celcon" are available from Celaneso Corporation, and ABS resins. (Acrylonitrile, butadiene and styrene) sold under the trademarks "Kralastic", "Lustron", "Cycolac * and" Abson "from Uniroyal Chemical Company, Monsanto Chemical Company, Borg-Warner Corporation, and Goodrich-Gulf Chemicals Inc. are available. Further These resins can be reinforced with about 10 to 20% glass fibers, which increases the stiffness, creep resistance and dimensional stability is improved. An ABS plastic reinforced with 20% glass fiber is preferable for this. These plastics are commercially available referred to as solid casting materials and can have properties which in part, such as the creep resistance, come close to that of non-ferrous metals such as zinc. While the physical properties change depending on the composition and the manufacturing method, should preferably a plastic can be selected, which e.g. has a minimal tensile strength

2
strength of about 633 kg / cm and a minimum compressive strength

2
of about 844 kg / cm. A rock wave hardness of about M75- M85 is characteristic of these plastics. In addition, the plastics should be only slightly hygroscopic, they should be dimensionally stable up to relatively high temperatures and only shrink slightly after casting.

Since moldable resins are used according to the invention, which are liquefied before hardening, it is possible and preferably the cavity between the stem and the opening by injecting fluid plastic through the outlet end 16 to fill under high pressure. Conventional injection molding devices are used for this purpose used. The substantial distance between the head region 24 of the handle and the opening simplifies the injection of the plastic and ensures that the plastic flows into this space and into the groove 26 and hardens as a uniform mass which completely fills the entire cavity. There

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the shoulder area 25 of the stem fitting tightly in the inlet area 17 of the opening is fitted, this causes a seal that the high pressure of the molten plastic during resists injection.

After hardening, the plastic compound 27 forms a uniform, tough, hard and strong connecting element, which is a mechanical Locking between the handle and the opening of the tool head guaranteed. The plastic compound has in the finished, molded form a cast bead 28, which is mechanically locked in the groove 26 and the upper area of the plastic compound increases in thickness and cross-section in the direction of the outlet end of the opening by one towards the wedge surfaces of the opening to form complementary part. As a result, a tight fit of the plastic compound is obtained with its bead in the area 26 reduced cross-section at the end of the stem 18 on shearing is loaded and a wedging between the outwardly widening surfaces of the opening 13, so that a loosening without Destruction of the relevant components is not possible. In addition, the inclined surfaces of the opening are at least partly that upper edge of the groove 26 arranged opposite, which by the hard plastic compound 27 are pressed apart.

Although the above-mentioned plastics which can be used in accordance with the present invention are mainly are castable connections that have no adhesive properties the lack of such adhesive properties is not detrimental to the Implementation of the invention as the holder according to the invention is achieved by mechanical means and does not depend on the adhesiveness. According to the preferred embodiment the plastic compound 27 in contact with a large surface the opening and the stem end and mainly with the largest area above the shoulder 25, and this is an advantage of the present invention, which in part the physical properties of the resin is to be assigned because it is not necessary a substantial surface contact between the wooden handle and the metallic opening to be provided, as is normally the case with known designs.

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-B-

An attachment of the stem in accordance with the present Invention allows a significant improvement in service life and resistance to loosening and against a possible loosening of the urinary head from the handle. In a known experiment which was used to measure the service life of the When attaching the handle, what is important is a transverse force on the handle in relation to the head to simulate the stress of pulling out a nail. To carry out this experiment the hammer head is clamped and a moment of 173Okgcm is repeatedly applied to the end of the handle in the direction of the claws exercised. In a conventional hammer in which the wooden handle is attached in a known manner by means of wedges thereby a play of 1.37 mm, which was measured at a distance of 77.20 mm from the opening after 150 load changes Test pieces of a hammer with a corresponding to the The wooden handle attached to the present invention, however, remained undamaged in this test and after the test was stopped 12,000 load changes was still not a game worth mentioning watch.

Corresponding to another common experiment which is also important for measuring the service life of a handle attachment hammer blows against a steel anvil at a speed of about 8 m / s are exerted in a test machine, which about the speed of a normal swivel movement of the Poor equals. In an experiment with a conventional hammer with a wooden handle in a known manner by means of wedges on the hammer head is attached you could play a game of about after 6000 hits Measure 1.63 mm at a distance of 77.20 mm from the opening. For comparison, test pieces of a hammer according to the present Invention tested and after 6000 hammer blows no significant play could be measured.

If there is moisture, try the wooden handle of a hammer is usually attached to one after 7 days specific humidity of 720 at 54 ° C and 7 additional days at a specific humidity of 40 and 22 ° C a game of measure about 1.88 mm at a distance of 77.20 mm from the opening,

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at

while / a hammer according to the present invention of the dem No game worth mentioning was submitted to the same attempt.

It should also be mentioned that in addition to the handle attachment, which ensures a firm connection between the handle and the hammer head under the high loads that the hammer exposed during normal use and which are very resistant the plastic used has a wide range of operating temperatures, good resistance to moisture against chemicals as well as has a good weather resistance which ensures that the connection does not become deteriorated as a result of the environmental conditions, especially if the plastic is also the upper end of the handle at the outlet end the opening covered as in the preferred embodiment is shown.

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Claims (7)

_ ίο _ PATENT TRANSP R_U_E_C H E. lJ striking tool with a metallic head, one in the head arranged opening for receiving a stem, which opening has an inlet end, an outlet end and an area with an enlarged Having cross-section in the vicinity of the outlet end, a stem with an end region arranged in the opening, characterized in that that the end region (24) of the handle (18) has a shoulder (25) for forming an interference fit in the tool head (10) an area (17) of the inlet end (14) of the opening (13) that furthermore the handle with a recess (26) in the Nhe of the shoulder and is provided with a head (24) which is arranged at a distance from the shoulder and is larger Cross-section as the saving, however, has a smaller cross-section than the area (19) with an enlarged cross-section of the opening has to form a game between the handle and the opening, and that a tough, hard and solid plastic (27) in the opening between the end of the handle and the tool head to form a mechanical lock between the Stem and head is cast. 2. Impact tool according to claim 1, characterized in that the area (19) of the opening (13) is provided with enlarged cross-section with side walls (20, 21) which move upwards and downwards are inclined on the outside in the direction of the outlet end (16) of the opening, and that the recess (26) of the stem (18) is one in the Shank is formed circumferential groove, so that the molded plastic (27) is mechanically locked in the groove and by a press fit is held between the stem and the opening. 3. Impact tool according to claim 1, characterized in that the molded plastic is a resin with a tensile strength of about 2
63O kg / cm and with a minimum compressive strength of about 2
Is 840 kg / cm. 4. Impact tool according to claim 1, characterized in that the molded plastic is a thermoplastic polycarbonate, acetal or ABS resin, which is optionally made by means of glass fiber is reinforced. 409839/0250 - xl - 5. Impact tool according to claim 1, characterized in that the enlarged cross section of the opening (13) a front and a rear surface (20,21) which upwards and downwards are inclined on the outside in the direction of the outlet end (16) of the opening so that the play around the head (24) of the stem (18) and the The opening extends around the entire circumference of the head, and that the molded plastic (27) is hard, solid and uniform Forms mass which is mechanically locked in the recess of the handle and by a press fit between the front one and the rear surface of the enlarged cross-sectional area (19) the opening is retained. 6. Impact tool according to claim 5, characterized in that the end region of the stem (18) ends shortly before the outlet end (16) of the opening (13) and that the plastic (27) is the end of the stem is covered and the outlet end of the opening is closed. 7. Impact tool according to claim 1, characterized in that the area (19) with enlarged cross-section of the opening (13) steadily increases in cross section in the direction of the outlet end (16) of the opening, so that the head (24) of the stem (18) is not larger than the cross section of the inlet end (14) is the opening and on the entire circumference at a distance from the inner surfaces (20, 21, 22, 23) of the opening is that the saving (26) of the handle is proportionate wide circumferential groove, and that the molded plastic (27) is a hard, solid and uniform mass, its thickness increases in the direction of the outlet end of the opening and thereby surrounds the head of the stem in order to achieve a jamming in the opening and this unitary mass has a cast-on bead (28), which protrudes into the circumferential groove to form a mechanical lock. 409839/0250 Blank page