Manufacturing Process of a Wheel Nut Wrench

Abstract

In order to provide a manufacturing process for a wheel nut wrench in which strength of a nut socket portion is increased even though the process is facilitated under a situation where a tube made of carbon steel such as S45C is used as a material, the process includes the steps of: using a tube-shaped steel tube, forming a nut socket shell portion having a cross section of a hexagonal shape at an end portion thereof by cold pressing, pressing a sleeve made by a belt-shaped steel plate being bent and having a cross section of a hexagonal shape into the nut socket shell portion, and unifying a nut socket portion with the sleeve by plastic deforming.

Description

CROSS-REFERENCE TO THE RELATED APPLICATION

This is a divisional of application Ser. No. 12/640,169 filed Dec. 17, 2009 which is incorporated here by reference, and which claimed priority on Japanese Patent Application No. 2009-162246 filed Jul. 8, 2009, which claim is repeated here.

FIELD OF THE INVENTION

The present invention relates to a manufacturing process for a wheel nut wrench suitable to be used for attaching/detaching wheels of a vehicle.

BACKGROUND ART

As for a wheel nut wrench, there are various types of wheel nut wrenches such as an open-ended type, a single-ended T shape, and a single-ended L shape. Among them, the single-ended L-shaped wheel nut wrench is constituted in a manner that a round bar (an inner filling body) made of carbon steel is used in general, a nut socket portion is formed at a tip thereof by hot forging, and then a side where this nut socket portion is provided is bent to an L shape. Among various types of wrenches such as this single-ended L-shaped wheel nut wrench, there is one sold as a single component, but most of them are each mounted in a vehicle as an accessory attached to the vehicle. Thus, the number of wrenches is enormous, and a significant cost reduction is required.

Thus, as for the single-ended L-shaped wheel nut wrench in particular, in contrast with a conventional wheel nut wrench made after a round bar is processed, a wheel nut wrench constituted in a manner that a nut socket portion is formed by cold forging with a tube made of carbon steel as a material, and a side where this nut socket portion is provided is bent to an L shape is well known in Japanese Patent Publication No. Hei 3-27297, Patent Document 1.

As for the conventionally well-known wheel nut wrench disclosed in above-described Patent Document 1, the material is a tube made of carbon steel of S45C, and furthermore the nut socket portion can be formed by cold forging, and therefore it makes it possible to reduce a manufacturing cost compared to the conventional wheel nut wrench with the round bar. However, in order to prevent that a thickness of the nut socket portion thins to thereby reduce strength, a process to make the nut socket portion thick is required, and it takes time for this process to be performed, so that a problem that a sufficient cost reduction cannot be achieved is caused.

The wheel nut wrench, in actual use, is used in such a way that a handle portion is hit with a hammer, a supporting tube is inserted into a handle portion, a foot or feet is/are put on a handle portion to apply a total body weight thereon, or the like, and thus, there is often a case that significant torsional pressure is applied on the nut socket portion.

Therefore, in the case when the single-ended L-shaped wheel nut wrench is manufactured with a tube, how deformation-resistant strength against torsional pressure on the nut socket portion is increased under a situation where processes are made as easy as possible is a next issue.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a manufacturing process for a wheel nut wrench in which strength of a nut socket portion is allowed to be increased even though a tube made of carbon steel is used as a material and processes are facilitated.

In order to achieve the above-described issue, the present invention comprising the steps of, using a tube-shaped steel tube, forming a nut socket shell portion having a cross section of a hexagonal shape at an end portion thereof by cold pressing, pressing a sleeve made by a belt-shaped steel plate being bent and having a cross section of a hexagonal shape into the nut socket shell portion, and unifying a nut socket portion with the sleeve by plastic deforming.

The manufacturing process of the wheel nut wrench according to the claims, wherein a shape of the nut socket shell portion is constituted in a manner that outer and inner peripheries thereof are both formed in a hexagonal shape.

The present invention is further characterized in that a heat treatment is performed for the sleeve.

The present invention is constituted as above, so that the following effects can be obtained.

A tube-shaped steel tube is used to form a handle portion, a bent portion, and a nut socket shell portion by cold pressing, and a sleeve that has a cross section of a hexagonal shape and is made of a steel plate similarly is pressed into the nut socket shell portion, and then a unification process is performed for the nut socket shell portion and the sleeve, and thereby unification of both the nut socket shell portion and the sleeve is achieved, resulting that a process of the nut socket shell portion becomes easy to be performed in particular. Consequently, it becomes possible to provide a manufacturing process for a wheel nut wrench in which a nut socket portion is strengthened by the sleeve under a situation where a tube-shaped steel tube allowed to be manufactured inexpensively is used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a wheel nut wrench which is manufactured according to the present invention;

FIG. 2 is a bottom view of the wheel nut wrench shown in FIG. 1;

FIG. 3 is a vertical cross-sectional view of the wheel nut wrench which is manufactured according to the present invention;

FIG. 4 is a cross sectional view of the wheel nut wrench which is manufactured according to the present invention when it is seen from a direction of an A-A line in FIG. 1;

FIG. 5 is a cross sectional view of the wheel nut wrench which is manufactured according to the present invention when it is seen from a direction of a B-B line in FIG. 1;

FIG. 6 is a perspective view of a sleeve in the wheel nut wrench which is manufactured according to the present invention;

FIG. 7 is a perspective view showing another embodiment of the sleeve in the wheel nut wrench which is manufactured according to the present invention;

FIG. 8 is a perspective view showing another embodiment of the sleeve in the wheel nut wrench which is manufactured according to the present invention;

FIG. 9 is a perspective view showing another embodiment of the sleeve in the wheel nut wrench which is manufactured according to the present invention;

FIG. 10(1) to FIG. 10(4) are explanatory views showing a manufacturing process of a wheel nut wrench according to the present invention;

FIG. 11 is an explanatory view showing a forming process of a nut socket shell portion in the wheel nut wrench according to the present invention;

FIG. 12(1) to FIG. 12(4) are explanatory views to explain the manufacturing process of the wheel nut wrench according to the present invention; and

FIG. 13(a) and FIG. 13(b) show a case when a single-ended L-shaped wheel nut wrench is used as a handle for a rotary shaft of a vehicle jack, and FIG. 13(a) is an explanatory view thereof and FIG. 13(b) is a partial enlarged cross sectional view of the explanatory view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment to implement the present invention is a manufacturing process for a wheel nut wrench made with a tube-shaped steel tube and provided with a nut socket portion at at least one end, a nut socket shell portion whose inner and outer peripheries are both formed in a hexagonal shape is provided at an end portion of the steel tube, a sleeve made of a steel plate and having a cross section of a hexagonal shape is pressed into this nut socket shell portion, and a portion of the nut socket shell portion is deformed toward the sleeve to thereby achieve unification of the nut socket portion and the sleeve.

Hereinafter, an embodiment of the present invention will be explained in detail based on the drawings in the case when the present invention is applied to a single-ended L-shaped wheel nut wrench, but the present invention can also be applied to an open-ended type wheel nut wrench and a T-shaped wheel nut wrench as it is besides the above.

FIG. 1 to FIG. 6 show one embodiment of a wheel nut wrench 1 which is manufactured according to the present invention. According to the drawings, the wheel nut wrench 1 according this embodiment is a single-ended L-shaped wheel nut wrench, and is made of a tube-shaped carbon steel tube, (which is also called a steel tube in the present application), such as tube-shaped S45C, for example. This single-ended L-shaped wheel wrench 1 is constituted by a handle portion 2 having a pierced hole 2a, a bent portion 3 provided on one side end portion side of this handle portion 2, and a nut socket portion 5 tube-expanded via a head portion 4 provided at a tip of this bent portion 3, and the nut socket portion 5 is constituted by a nut socket shell portion 5a and a sleeve 7 inserted into and fixed to this nut socket shell portion. This single-ended L-shaped wheel nut wrench 1 is constituted by processing a tube-shaped material, and thus a communication hole 6 is formed through from the nut socket portion 5 to the handle portion 2. Further, in this single-ended L-shaped wheel nut wrench 1, a material thereof is a carbon steel tube as described above, but besides the above, stainless steel (SUS) or aluminum alloy can be used. The pierced hole 2a is formed in a manner that it is in a substantially elliptical shape and as for sizes on an entry 2b side and an exit 2c side, the entry 2b side is large and the exit 2c side is small. However, the present invention is not limited to the above.

As shown in FIG. 2 in particular, the handle portion 2, the bent portion 3, the head portion 4, and the nut socket shell portion 5a of the nut socket portion 5 are substantially uniform in thickness, and in particular, a thick portion is not formed. Thus, there is no need to form a thick portion by a tube shrinking process or an ironing process. Therefore, steps of a process are reduced and the process is facilitated, and a tube expanding deformation process can be performed without exerting unreasonable force on the steel tube.

As for a shape of the nut socket shell portion 5a as well, inner and outer peripheries both have a cross section of a hexagonal shape, in which a thickness between the inner and outer peripheries is substantially the same as those of other portions, and the sleeve 7 that has a cross section of a hexagonal shape and has the thickness same as that of the nut socket shell portion 5a similarly is pressed into and fixed to the inside. However, the nut socket shell portion 5a is tube-expanded from a tube diameter of the handle portion 2, and therefore, the thickness is slightly thinner than those of the other portions in the strict sense, but a thickness to be reduced is about 0.5 mm, and there is no significant difference from the other portions. However, since the sleeve 7 is inserted into and fixed to this nut socket shell portion 5a, as the nut socket portion 5, the total thickness is thicker than those of the handle portion 2, the bent portion 3, and the like besides the above.

This sleeve 7 is formed in a manner that a belt-shaped carbon steel plate made of, for example, S45C, (which is also called a steel plate in the present application), is bent to have a cross section of a hexagonal shape, and as shown in FIG. 6 in particular, a joint 7a is formed in one of flat plate portions 7b. As for this joint 7a, a joint whose both ends are simply abutted and a joint whose both ends are welded together can be considered, and sufficient strength can be obtained by only abutting. A material for this sleeve 7 is also S45C in this embodiment, but stainless steel (SUS) can also be used.

Further, in respective corner portions 7d and one of the flat plate portions 7d of the sleeve 7, as shown in FIG. 5 and FIG. 6 in particular, fixing holes 7c are provided. As shown in FIG. 4, after the sleeve 7 is pressed into the nut socket shell portion 5a, a portion corresponding to each of corner portions 5b of the nut socket shell portion 5a and each of the fixing holes 7c of the flat plate portions 7b is punched from the outside by using a punch, and the inside of the nut socket shell portion 5a is bulged to the fixing holes 7c to be engaged to the fixing holes 7c, and thereby unification of the sleeve 7 and the nut socket shell portion 5a is achieved. In the drawing, concave portions made by punching are denoted by a reference numeral 5c.

This fixing hole 7c, as shown in FIG. 5 and FIG. 6 in particular, is provided in each of the corner portions 7d and one of the flat plate portions 7b of the sleeve 7, but the present invention is not limited to these positions. Accordingly, in the present application, the respective corner portions 7d and the flat plate portions 7d are also called a peripheral wall altogether. Further, the number of the fixing holes 7c is not limited in particular, but there is a need to provide the fixing holes 7c plurally. In the case when the fixing hole 7c is provided in the flat plate portion 7b, it may be possible to omit providing the fixing hole in one or two of the corner portions 7d adjacent to the flat plate portion 7b.

FIG. 7 shows another embodiment of the sleeve. According to the drawing, a sleeve 10 according to this embodiment is constituted in a manner that a formation of a joint 10a is a jagged pattern.

This embodiment constituted in this manner makes it possible to effectively prevent the sleeve 10 from twisting toward an axis direction even when a strong torque is exerted on the nut socket portion of the wheel nut wrench in loosening or tightening a wheel nut. The jagged pattern of the joint 10a of this sleeve 10 may be zigzag, or as is a sleeve 11 shown in FIG. 8, it may be constituted to have a joint 11a having a crank shape.

FIG. 9 shows still another embodiment of the sleeve. According to the drawing, fixing holes 12a provided in a sleeve 12 are all provided in corner portions 12b.

Even when this embodiment is constituted in this manner, an object of the present invention can be achieved, and this embodiment has an advantage that it is possible to prevent that by punching, flat plate portions 12c of the sleeve 12 are distorted inwardly to be deformed. Note that a reference numeral 12d denotes a joint.

FIG. 10(1) to FIG. 10(4) through FIG. 12(1) to FIG. 12(4) show one embodiment of a manufacturing process of a wheel nut wrench according to the present invention.

First, as shown in FIG. 10(1), a carbon steel tube having a tube diameter of 19 m/m and a thickness of 2 m/m is cut in an appropriate length to be formed as a blank tube A, and deburring or the like is performed. Next, a side where the nut socket portion is provided, being one end portion of the blank tube A, is placed in a beveling die in a press machine, which is not shown, and by using a not-shown punch bar, as shown in FIG. 10(2), a first tube expansion is performed to obtain a first processed product B. Next, as for the first processed product B made after this first tube expansion is performed, a portion of the first processed product B, where the tube expansion is performed, is placed in another beveling die that is not shown and whose inside diameter is further expanded, and by using a not-shown punch bar whose diameter is larger than that of the punch bar used in the first tube expansion, a second tube expansion is performed as shown in FIG. 10(3) to obtain a second processed product C. Next, a portion of this second processed product C, where the tube expansion is performed, as shown in FIG. 11, is placed in a beveling die 13 provided with a hexagonal shaped hole in a plane, and by using a punch bar 14 having a cross section of a hexagonal shape similarly, as shown in FIG. 10(4), the portion is formed in a hexagonal shape in a plane to obtain a third processed product D having a nut socket shell portion 15. At this time, a thickness of the portion where the nut socket shell portion 15 in a hexagonal shape in a plane is formed is uniform as shown in FIG. 5 and FIG. 6, but it is possible to make the thickness of the portion thicker or thinner than those of other portions of the blank tube depending on the way how the nut socket shell portion 15 is formed. When the thickness is made thick, strength thereof is increased, and this portion is correlative to strength of a later-described sleeve. The formation of the nut socket shell portion 15 in the blank tube A as above is performed by cold pressing. Note that the tube diameter and thickness of the blank tube A are not limited to the above.

When the nut socket shell portion 15 in a hexagonal shape in a plane cross section is formed at the one end portion of the blank tube A by tube expansion according to the above manner, as shown in FIG. 12(a), the step of pressing a sleeve 16 in a hexagonal shape in a plane that is formed at other steps into the nut socket shell portion 15 is started. Here, formation of the sleeve 16 is explained. The sleeve 16 is formed in a manner that a coiled carbon steel plate made of, for example, S45C and having a thickness of 2 mm and a width of 20 mm is used, and the carbon steel plate is cut while fixing holes 16a are being punched through by a not-shown progressive press machine and the carbon steel plate is being bent to a hexagonal shape in a plane (this hexagonal shape is adjusted to a shape of an outside diameter of a wheel nut). At this time, a joint 16b is made, but it is preferable that this joint 16b is provided with a slight opening, (which is about 0.1 to 0.5 mm). The thickness of the sleeve 16 is 2 mm in accordance with the thickness of the blank tube, but this thickness is not limited.

Further, the opening in the joint 16b is an opening that is eliminated because the entire sleeve 16 shrinks when the sleeve 16 is pressed into the nut socket shell portion 15. A shape of the joint 16b is straight in this embodiment, but it is arbitrary that the shape thereof is set as a zigzag shape, a clank shape, or the like. When a zigzag shape is applied, there is an effect that it is possible to prevent that the sleeve 16 is twisted by torsional pressure, thereby a position of the sleeve 16 being displaced in an up and down direction when a wheel nut is tightened or loosened. The joint 16b is preferably in a flat plate portion of the sleeve 16, but it is also possible to bring the joint 16b to a corner portion. Further, although an increase in cost is caused a little, it is also possible to weld the joint 16b. As for welding, continuous welding, spot welding, or the like is available.

The steps until the sleeve 16 in a hexagonal shape in a plane is formed are a cold press process, and it is preferable that a heat treatment such as quenching and tempering is performed after the sleeve 16 is formed to thereby increase its strength.

As shown in FIG. 12(2), after the sleeve 16 is pressed into and fixed to the nut socket shell portion 15 to obtain a fourth processed product E, as shown in FIG. 12(1) and FIG. 12(3), punching is performed to the fixing hole 16a of the sleeve 16 from the outside of the nut socket shell portion 15 by using a punch bar 17, and as shown in FIG. 5 in particular, the nut socket shell portion 15 is bulged to each of the fixing holes 16a to form a nut socket portion 18, which is set as a fifth processed product F. Next, as shown in FIG. 12(4), a handle portion is bent to form a bent portion 19, and a pierced hole 2a is provided by a press machine and a plated finish is performed, and then a finished product G is made. Note that an angle of the bent portion 19 can be selected arbitrarily.

Further, an order in which the pierced hole 2a is provided is not limited. It is arbitrary that the pierced hole 2a is not provided at a later step of the manufacturing process as described above but it is provided at a different and earlier process. This pierced hole 2a, as shown in FIG. 13(a) and FIG. 13(b), is to be used when a single-ended L-shaped wheel nut wrench 20 is used as a rotary handle to a rotary shaft 21 of a vehicle jack. As shown in FIG. 13(b) in particular, when a size of the pierced hole 2a is changed by making an entry 2b of this pierced hole 2a large and making an exit 2c thereof small, in the case when a tip 21a of the rotary shaft 21 is tapered, there is an advantage that the tapered tip can be fit into the pierced hole 2a without any trouble because a handle portion 2 is tube shaped and a predetermined interval is provided between the entry 2b and the exit 2c. However, a shape of the pierced hole 2a is according to a shape of the rotary shaft 21 to be inserted, and it is not limited to the above in this embodiment.

Note that in the above explanation, the case when the present invention is applied to the single-ended L-shaped wheel nut wrench is explained, but as described above, it goes without saying that the present invention can also be applied to an open-ended type wheel nut wrench and a single-ended T-shaped wheel nut wrench besides the above.

The present invention is constituted as above, and thus it is tube shaped and strong against torsional deformation, and can be manufactured inexpensively. Accordingly, the present invention has a possibility to be widely used as a manufacturing process of a wheel nut wrench for vehicles in particular.

Claims

1. A manufacturing process of a wheel nut wrench comprising the steps of:

providing a tube-shaped steel tube;

forming a nut socket shell portion having a cross section of a hexagonal shape at an end portion of the steel tube by cold pressing;

pressing a sleeve made by a belt-shaped steel plate being bent and having a cross section of a hexagonal shape into the nut socket shell portion; and

unifying a nut socket portion with the sleeve by plastic deforming.

2. The manufacturing process of the wheel nut wrench according to claim 1, wherein

a shape of the nut socket shell portion is constituted in a manner that outer and inner peripheries thereof are both formed in a hexagonal shape.

3. The manufacturing process of the wheel nut wrench according to claim 1, wherein

a heat treatment is performed for the sleeve.