Method for producing a wrench socket

The present invention relates to a method for producing a wrench socket and, more particularly, to a method for producing a wrench socket having size indicia by direct pressing.

<patcit id="pcit0001" dnum="US4839059A"><text>U.S. Patent Nos. 4,839,059</text></patcit> and <patcit id="pcit0002" dnum="US4947713A"><text>4,947,713 both to Arnold</text></patcit> discloses an elastomeric sleeve mounted to a rear portion of a wrench socket. The elastomeric sleeve is integrally molded from a suitable plastic, rubber or other elastomeric material. The elastomeric sleeve is provided with suitable size indicia formed by integral casting or molding. A suitable adhesive secures the sleeve on the socket and precludes an axial separation therebetween. In another embodiment disclosed in <patcit id="pcit0003" dnum="US4839059A"><text>U.S. Patent No. 4,839,059</text></patcit>, a pressure-sensitive laminated label is bonded to the sleeve and includes size indicia formed by impression stamping, printing, engraving or other methods. However, the size indicia is not directly formed on the sleeve and involves complicated manufacturing procedures, leading to waste of time and costs.

<patcit id="pcit0004" dnum="US442837A"><text>U.S. Design Patent No. 442,837 to Porras </text></patcit>discloses a grippable drive socket having knurls on an outer periphery thereof and size indicia formed in the outer periphery by rolling. <patcit id="pcit0005" dnum="US6761093B"><text>U.S. Patent No. 6,761,093 to Chang</text></patcit> and <patcit id="pcit0006" dnum="US20060090612A1"><text>U.S. Patent Publication No. 2006/0090612 A1</text></patcit> also disclose socket having size indicia formed on the outer periphery by rolling. However, the distance from the size indicia to the outer periphery of the socket must be limited to avoid damage to the structural strength and/or mechanical properties of the hollow socket formed by rolling. As a result, the size indicia is liable to be damaged due to impact or abrasion.

<patcit id="pcit0007" dnum="US7028588B"><text>U. S. Patent No. 7, 028, 588</text></patcit> to Shihdiscloses a tool including a rectangular areaprinted on a cylindrical outer surface thereof. An identification mark or numeral is formed on the rectangular area as a representation of a size of the tool. The rectangular printing area and the numeral have different colors. The numeral is formed by cutting through the rectangular printing area to form a stencil for exposing a metal color of the tool and providing a contrast of the numeral to other portions of the area. Deformation of the tool resulting from stamping is avoided. However, formation of the numeral by cutting the printing area to form a stencil is much complicated and expensive. Furthermore, the numeral thus formed has a film-like structure that is liable to be damaged or become blurred due to impact or abrasion.

A need exists for a method for producing a wrench socket with size indicia that is more resistant to impact and/or abrasion.

The present invention solves this need and other problems in the field of production of wrench sockets by providing, in a preferred example, a method for producing a wrench socket by direct pressing size indicia. The method includes forming, preferably forging, a metal blank to form a socket including first and second end portions. The first end portion includes an engaging hole and an outer circumferential wall surrounding the engaging hole. The engaging hole is adapted to couple with a wrench, and the second end portion is adapted to drive a fastener or the like. A support rod portion is inserted into the engaging hole of the first end portion of the socket. The support rod portion received in the engaging hole has a shape complementarily corresponding to that of the engaging hole. The outer peripheral surface of the first end portion of the socket is locally pressed to form debossed or - preferably - embossed size indicia in the outer peripheral surface of the first end portion of the socket. The support rod portion is removed from the engaging hole of the socket after pressing. Then, surface treatment is carried out on the socket.

During pressing, the pressing force imparted to the socket can be effectively transmitted to the support rod portion fittingly received in the engaging hole whereas the support rod portion exerts a reactive force to the circumferential wall defining the engaging hole to avoid undesired deformation of the size indicia and/or of the seize of the engaging hole. Separate formation of an indicia sleeve and a socket and subsequent coupling between the indicia sleeve and the socket in the prior art methods are avoided.

An outline surface of the socket can be processed after forging and before inserting the support rod portion. In addition or as an alternative, the outline surface of the socket can be processed after removing the support rod portion and before surface treatment of the socket. Furthermore, heat treatment of the socket can be carried out after processing the outline surface of the socket and before surface treatment of the socket.

The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.The illustrative embodiments may best be described by reference to the accompanying drawings where: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> shows a flowchart illustrating a method of an example according to the preferred teachings of the present invention.</li><li><figref idref="f0002">FIG. 2</figref> shows a perspective view illustrating insertion of a support rod portion into a semi-product of a wrench socket.</li><li><figref idref="f0003">FIG. 3</figref> shows a perspective view illustrating formation of size indicia on the semi-product of the wrench socket of <figref idref="f0002">FIG. 2</figref> by locally pressing the semi-product with two dies.</li><li><figref idref="f0004">FIG. 4</figref> shows a perspective view illustrating removal of the support rod portion after formation of the size indicia.</li><li><figref idref="f0005">FIG. 5</figref> shows a side elevational view of the wrench socket with two indicia areas formed with the method according to the preferred teachings of the present invention.</li><li><figref idref="f0006">FIG. 6</figref> shows a cross sectional view of the wrench socket of <figref idref="f0005">FIG. 5</figref> according to section line 6-6 of <figref idref="f0005">FIG. 5</figref>.</li><li><figref idref="f0007">FIG. 7</figref> shows a perspective view of a final product of the wrench socket of <figref idref="f0005">FIG. 5</figref>.</li><li><figref idref="f0008">FIG. 8</figref> shows a flowchart illustrating a method of another example according to the preferred teachings of the present invention.</li><li><figref idref="f0009">FIG. 9</figref> shows a flowchart illustrating a method of a further example according to the preferred teachings of the present invention.</li><li><figref idref="f0010">FIG. 10</figref> shows a perspective view illustrating formation of size indicia on a semi-product of a wrench socket by locally pressing the semi-product with a die and a pressing rod.</li><li><figref idref="f0011">FIG. 11</figref> shows a cross sectional view of a wrench socket with a single indicia area.</li><li><figref idref="f0012">FIG. 12</figref> shows a perspective view of another wrench socket produced by the method according to the preferred teachings of the present invention.</li><li><figref idref="f0013">FIG. 13</figref> shows a side elevational view of the wrench socket of <figref idref="f0012">FIG. 12</figref></li><li><figref idref="f0014">FIG. 14</figref> shows a cross sectional view of the wrench socket of <figref idref="f0013">FIG. 13</figref> according to section line 14-14 of <figref idref="f0013">FIG. 13</figref>.</li><li><figref idref="f0015">FIG. 15</figref> shows a perspective view of a further wrench socket produced by the method according to the preferred teachings of the present invention.</li><li><figref idref="f0016">FIG. 16</figref> shows a perspective view illustrating formation of size indicia on a semi-product of a wrench socket by locally pressing the semi-product with four dies.</li></ul>

All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the Figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.

Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms "first", "second", "end portion", "portion", "section", "radial", "outward", "periphery", "length", "height", and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention. It should further be understood by the skilled persons that the term "indicia" does not mean a restriction to a plurality of indiciums. It also includes the meaning of a single indicium.

<figref idref="f0001">FIG. 1</figref> shows a flowchart illustrating a method for producing a wrench socket of an example according to the preferred teachings of the present invention. In this example, a metal blank is forged to form a socket 10. As illustrated in <figref idref="f0002">FIG. 2</figref>, the socket 10 includes a first end portion 101 having an engaging hole 11 for coupling with an engaging portion such as a drive column of a wrench and a second end portion 102 designed as a femal coupling by also including a multi-edged engaging hole (not shown in the drawings) for coupling with and driving a fastener such as a nut, bolt head, or the like. In other embodiments of the present invention, the second end portion 102 can even be designed as a male coupling portion (not shown) including a multi-edged engaging pin. The engaging hole 11 is shown as having square cross sections. However, the engaging hole 11 can have other multi-edged cross sections including but not limited to hexagonal and dodecagonal cross sections.

A support rod portion 90 (<figref idref="f0002">FIG. 2</figref>) is then inserted into the engaging hole 11 of the first end portion 101 of the socket 10. The support rod portion 90 received in the engaging hole 11 has a shape corresponding to that of the engaging hole 11 to be complementary thereto. Namely, the engaging hole 11 fittingly receives the support rod portion 90. Though the support rod portion 90 is preferably, as shown in the drawings, an end portion of a support rod, the support rod portion 90 may have a design of a plug.

Next, a cylindrical outer peripheral surface of the first end portion 101 of the socket 10 forming a circumferential wall surrounding the engaging hole 11 is locally pressed by stamping two dies 91 (<figref idref="f0003">FIG. 3</figref>) in two diametrically opposed areas thereof to form two diametrically opposed indicia areas 12 (<figref idref="f0004 f0005 f0006">FIGS. 4-6</figref>) in the outer peripheral surface of the first end portion 101 of the socket 10. During pressing, the pressing forces imparted from the dies 91 to the socket 10 can be effectively transmitted to the support rod portion 90 fittingly received in the engaging hole 11 whereas the support rod portion 90 exerts a reactive force to the circumferential wall defining the engaging hole 11 to avoid undesired deformation of the indicia areas 12 and/or deformation of the circumferential wall.

The indicia areas 12 is formed on the first end portion 101 of the socket 10 rather than on the second end portion 102, if the wall thickness of the first end portion 101 is larger than that of the second end portion 102 and, thus, allows direct pressing into the outer peripheral surface of the first endportion 101, meaning more favorable conditions for displacement of material without the risk of undesired deformation of and/or damage to the socket 10. Separate formation of an indicia sleeve and a socket and subsequent coupling between the indicia sleeve and the socket in the prior art methods are avoided.

It can be appreciated that one of the dies 91 can be replaced by an anvil rod 92 (<figref idref="f0010">FIG. 10</figref>) to form a single indicia area 12 on the socket 10 by a single die 91 and to oppose the pressing force by anvil rod 92 that has a recess formed by a concave-cylindrical surface of a radius of curvature that is similar to the outer radius of curvature of the cylindrical outer surface of end portion 101 of the socket 10 . It can be further appreciated that more dies 91 can be utilized to form more than two indicia areas 12 on the outer peripheral surface of the first end portion 101 of the socket 10. For example, the first end portion 101 of the socket 10 can be pressed with four dies 91 (<figref idref="f0016">FIG. 16</figref>) at two pairs of diametrically opposite sections of the outer peripheral surface of the first end portion 101 to form four indicia areas 12, or can be pressed with two dies 91 each accompanied by an anvil die at diametrically opposite locations (not shown).

After formation of the indicia areas 12, the support rod portion 90 is removed from the engaging hole 11 of the socket 10 (<figref idref="f0004">FIG. 4</figref>).

In the embodiments shown in <figref idref="f0003 f0004 f0005 f0006 f0007">FIGS. 3 to 7</figref>, each of dies 91 include debossed mirror images (matrices) of the indicia to be formed in the indicia areas 12, so that the indicia in indicia area 12 are of embossed configuration. Each indicia area 12 includes a flat recess having a bottom surface 121 radially inside of the outer circular periphery of the first end portion 101. Each indicia area 12 further includes embossed size indicia 122 protruding radially outward from the bottom surface 121 and having a height not beyond the outer periphery of the first end portion 101 of the socket 10. Namely, a top 123 of the size indicia 122 is spaced inside from the outer periphery of the first end portion 101 of the socket 10.

The socket 10 can be subj ected to surface treating to obtain a final product of a wrench socket 10 with two indicia areas 12 (<figref idref="f0007">FIG. 7</figref>). Surface treatment includes vibration polishing treatment including chemical surface treatment. The vibration polishing treatment is followed by electroplating the outer peripheral surface of the socket 10. Other surface treatment can be utilized. For example, the vibration polishing treatment can be followed by sand blasting the outer peripheral surface of the socket 10 to obtain the required surface treating effect and to obtain the final product of the wrench socket 10.

<figref idref="f0008">FIG. 8</figref> shows a flowchart illustrating a method of another example according to the preferred teachings of the present invention. Compared to the flowchart of <figref idref="f0001">FIG. 1</figref>, in the example of the method according to the preferred teachings of the present invention shown in <figref idref="f0008">FIG. 8</figref>, the outline of the socket 10 is processed to a desired specification and then subjected to heat treatment after removing the support rod portion 90 and before surface treating the socket 10. The outline processing includes milling a peripheral wall defining the engaging hole 11 of the first end portion 101 of the socket 10 to form a groove that is capable of retaining the drive column of the wrench in the engaging hole 11, preventing disengagement of the socket 11 during operation of the socket wrench. The outline processing can further include finish milling or rough milling of the socket 10. For example, the outline processing can include milling two end faces of the socket 10 to provide the socket 10 with a length of the desired specification, trimming the outer peripheral surface of the socket 10 by milling, and/or surface polishing the outer peripheral surface of the socket 10 by grinding including but not limited to centerless grinding. The heat treatment is carried out after outline processing and before surface treatment of the socket 10 to provide the socket 10 with the desired structural strength. It can be appreciated that the outline processing after removal of the support rod portion 90 and before surface treatment of the socket 10 is carried out to eliminate possible deformation of the socket 10 after pressing.

<figref idref="f0009">FIG. 9</figref> shows a flowchart illustrating a method of a further example according to the preferred teachings of the present invention. Compared to the flowchart of <figref idref="f0008">FIG. 8</figref>, the example of the method according to the preferred teachings of the present invention shown in <figref idref="f0009">FIG. 9</figref> further includes processing the outline of the socket 10 to the desired specification after forging and before insertion of the support rod 90. The outline processing after forging and before insertion of the support rod 90 can include milling the first and second end portions 101 and 102 of the socket 10 to different diameters. The outline processing after forging and before insertion of the support rod portion 90 can further include finish milling or rough milling of the socket 10. For example, the outline processing after forging and before insertion of the support rod portion 90 can include milling two end faces of the socket 10 to provide the socket 10 with a length of the desired specification and/or surface polishing the outer peripheral surface of the socket 10 by grinding. It can be appreciated that outline processing can be carried out after removal of the support rod portion 90 and before surface treatment of the socket 10 to eliminate possible deformation of the socket 10 after pressing due to displacement of material therof.

The socket 10 shown in <figref idref="f0007">FIG. 7</figref> is a so-called European-type socket in which the first end portion 101 and the second end portion 102 have different diameters whereas a shoulder is formed between the first and second end portions 101 and 102. However, the method according to the preferred teachings of the present invention can be utilized to produce sockets of other types such as the so-called American-type socket 20 shown in <figref idref="f0015">FIG. 15</figref> in which first and second end portions 201 and 202 of the socket 20 have identical diameter without shoulders therebetween. It can be appreciated that one or more indicia areas 122 can be formed on the outer peripheral surface of the first end portion 201 of the socket 20 having an engaging hole 11 for coupling with a wrench, the indicia areas being preferably formed at a location opposite to a flat inner wall surface of the engaging hole 11 where wall thickness of the circumferential wall surrounding the engaging hole is at a maximum.

The dies 90 can have other forms to form different size indicia on the socket 10. For example, the socket 10 shown in <figref idref="f0012 f0013 f0014">FIGS. 12 to 14</figref> includes two indicia areas 13 each having debossed size indicia 132 protruding radially inward from the outer peripheral surface of the first end portion 101 of the socket 10. Other forms of the indicia areas 12, 13 and the size indicia 122, 132 would be within the skill of the art.

According to the preferred teachings of the present invention, the size indicia 122, 132 of the socket 10 are formed by direct pressing during which the pressing force imparted to the socket 10 can be effectively transmitted to the support rod portion 90 without causingdeformationof and damage to the indicia 122, 132. The disadvantages of conventional methods involving separate formationof an indicia sleeve anda socket and subsequent coupling between the indicia sleeve and the socket are avoided. Furthermore, the socket 10 can be produced at low costs by the method according to the preferred teachings of the present invention. Furthermore, the method according to the preferred teachings of the present invention can be utilized to form trademarks or other marks in the outer peripheral surface of the socket 10 according to product needs.

Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.