Cylindrical Nut And Wrench

Abstract

My invention relates to a new and improved type of cylindrical nut having an outer scalloped periphery and an improved wrench which has mating means including a pin to provide operative engagement with the cylindrical nut. The pin being located near the arcuate surface of the wrench, and having its center offset beyond the arcuate surface a distance proportional to the pin diameter in the order of one-sixth of the pin diameter to provide optimum design to all elements of the mating means.

Description

This invention applies to the transfer of torque from one mechanical member to another element thru a cylindrical mated connection and specifically relates to the combination of a simple type of cylindrical grooved surface or nut and an improved wrench therefor. The nut and wrench are both inexpensive to manufacture and also provide the maximum amount of efficient operation. The wrench has an inner radius substantially the same as the outer radius of the nut with a pin arranged to engage one or more of the grooved surfaces of the cylindrical member or nut.

An object of this invention is to provide the torque transfer from a mechanical member thru a pin to a driven element. This transfer of torque passes thru a pin located in the wrench to the nut by a combination of shear and compressive stress against the pin.

Another object of this invention is the use of a cylindrical nut having cylindrical grooves along its periphery to engage a cylindrical pin in the wrench. The axis of the pin is parallel with that of the nut and located in the wrench such that part of its cylindrical surface projects into a groove of the nut.

Still another object of this invention is to reduce the manufacturing cost and yet provide an efficient and inexpensive nut which can be made of cylindrical bar stock and will require a minimum amount of material.

A feature of this invention is the provision of a simple open-end wrench of substantially the same radius as the cylindrical nut and containing one or more cylindrical pins located along its inside periphery to engage one or more grooves in the nut.

Another feature of this invention is the provision of a band where extreme forces are applied to a nut when the cross-sectional area between the inner and outer diameters is relatively thin.

Still another feature of this invention is that the mating surfaces of the nut and wrench are so arranged that the wrench may be left in operative engagement with the nut at all times.

The combined nut and wrench of this invention is an improvement over the prior art for the reason that square and hexagonal nuts require square or hexagonal bar stock in their manufacture which is more expensive and requires more material than the same size in cylindrical stock of which nuts of this invention use in their manufacture.

The corners of both the square and hexagonal nuts tend to get rounded over with continued use, whereas with the nuts of this invention the outer surface is always in such a mated engagement with the wrench that it protects the grooves from this rounding over effect. Also the pin of the wrench is forced by this mated engagement to rotate into the groove of the nut firmly and directly.

The wrench and nuts of this invention are also an improvement over the prior art type of spanner wrenches. One type being with a pin at one end thereof and an associated nut with holes in its outer diameter to engage the pin of the wrench. In another type, the wrench has two pins arranged to engage a pair of holes in the face of the nut. In such wrenches the pins of the spanner wrench will tend to bend and the holes of the nut tear out if excessive force is applied thereto. Whereas with the wrench of this invention the pin or engaging member is in an axis parallel to the axis of the nut and the grooved surfaces of the nut so that a much greater force can be applied to the driving member and transfered to the driven element before shearing can take place in the pin of the wrench or deformation of the outer surface of the nut.

This invention will best be understood by referring to the accompanying drawings in which

FIG. 1 is a plan view of the nut of this invention.

FIG. 2 is an elevation of FIG. 1, part of which is in section.

FIG. 3 is a plan view of the wrench, showing a cross section of the handle portion.

FIG. 4 is a sectional elevation of a portion of FIG. 3.

FIG. 5 is a diagram showing a portion of the wrench and the forces which are transfered thru the pin.

FIG. 6 is a plan view of a wrench having three pins.

FIG. 7 is another plan view showing a modified wrench having a band attached.

Referring now in detail to FIGS. 1 and 2, the cylindrical nut 1 which is made of any type of durable material including metals, metal alloys, and plastics. The outer periphery of nut 1 has a plurality of cylindrical grooves 2 which are uniformally spaced. The nut shown has eight grooves but it is to be understood that one or any number of grooves may be used.

The inner surface of the nut is threaded at 3 with any suitable thread form. The nut shown in the drawing, as an example, is one having a 2-inch outer cylindrical diameter, 1 3/8 -inch internal thread with 8 threads per inch, a thickness of 1/2 inch, and 3/8 -inch diameter pin grooves.

In the practice of this invention, I propose establishing standard nut configurations. Each size would cover a specified internal thread range and would be grooved for a standard pin diameter proportional to that of the nut diameter. For example, a 2-inch diameter nut could have threads from 3/4 to 1 3/8 -inch diameter using any desired thread form and grooved for a 3/8 -inch diameter pin. Other standard nut diameters could be 1, 3, 4, 5, 6, etc., inches having proportional internal thread ranges.

Referring now to FIGS. 3 and 4 the wrench 4 has an arcuate surface 5 which extends approximately 30.degree. beyond the center of nut 1 on both sides. The extension of this arcuate surface beyond the center insures a secure mating of wrench 4 with nut 1 and permits the wrench to be left in an operative engagement on the nut.

The central portion of the arcuate surface has located therein a pin 6 which is driven into an aperture 7 in the body portion of the wrench 4 and is positioned such as to extend beyond the arcuate portion 5 so as to engage a groove 2 in nut 1. The thickness of wrench 4 is similar to nut 1.

The outer surface 8 of the wrench 4 extends from the ends 9 of the arcuate surface at an increasing sectional portion to a point 10 where it forms the handle portion 11 which is of sufficient length to give proper leverage and to provide a firm hold for the operator.

Referring now to FIG. 5, the diagram shows an example of how the size and position of the pin should be in order to give the maximum life to both the wrench and the nut. One example of this would be for a 3/8 -inch diameter pin for a 2-inch diameter nut with the pin axis located 1/16 inch beyond the arcuate surface into the wrench, or the proportion of one-sixth of the pin diameter. Torque applied to the wrench is transfered thru pin 6 to nut 1. This is represented by a force F at an angle .theta., drawn at 60.degree. , with respect to line L between center C of nut 1 and the center of pin 6. It should be noted, that if the pin 6 is set further into the body of wrench 4 it will be held more securely. Yet at the same time, this would cause angle .theta. to become less and increase force F thereby decreasing the effectiveness of the wrench.

In the operation of this invention, applied torque T would cause wrench 6 to rotate freely around nut 1 if pin 6 where missing. With pin 6 in place, torque T is transferred from driving member 4 to driven element 1 thru pin 6 by a combination of shear S and outward radial force R on pin 6.

A major advantage of this invention over prior art is due to the unusual manner in which the pin is positioned to resist shear force. Normally a pin in a spanner wrench is placed such that it will resist shear across its cylindrical cross section. Whereas in this invention shear force S is directed along surface 5 between elements 1 and 4 and is distributed across the longitudinal cross section of pin 6. The advantage is that for a pin of a length equivalent to its diameter it has approximately 1.273 times more longitudinal than circular area and this can be increased by extending the pin. Therefore with this greater cross section area possible, greater shear forces can be resisted with the same pin.

The outward radial force R is caused by pin 6 being forced out of groove 2 in nut 1 as torque T is applied to wrench 4. This force would be at a minimum for a pin which is half exposed and would increase as less of the pin is exposed to the nut. The force R would tend to compress pin 6 into the driving member 4 and tighten the connection between the elements. This force is also distributed across the longitudinal area of the pin.

FIG. 6 shows a modified wrench 12 which has located in its arcuate internal surface three pins 13, 14, and 15 which are arranged to engage two additional mated grooves in nut 1.

FIG. 7 shows another modified wrench having a band 16 secured by any suitable means such as pins 17. The arcuate surface is provided with two pins 18 and 19. This type of wrench is optimum where the wall thickness of the nut 1 is relatively thin and a maximum amount of torque is to be applied to the nut 1 without deforming it. This wrench is also practical in situations where access to a nut is limited.

Because all the shapes used in this nut and wrench combination are round they have a more natural resistance to wear than square and hexagonal nuts of which the corners tend to be rounded through continued use.

This invention is especially adapted to relatively large diameter nuts where the savings in material is much greater and the forces are also more extreme. Yet it would not be limited thereto as the same conditions exist in small nuts such as 1/4 to 3/4 inch diameter threads.

Although this invention has been described as a combination of a cylindrical nut and a wrench therefor, it is to be understood that the transfer of torque of this invention may be also applied to an external cylindrical member having similar mating configurations.

Although this invention has been described as a wrench having a pin 6 driven into body portion 7 and extending beyond the arcuate portion 5, it is to be understood that any type of mating means is within the scope of this invention. In such mating means the pin could be substituted with a projection extending beyond the arcuate portion of the wrench which could be formed by casting or forging in a one-piece construction.

Claims

I claim:

1. A wrench for a cylindrical nut having a plurality of parallel grooves located on its outer portion, said wrench having an arcuate portion and a handle portion, circular parallel mating means for said nut extending beyond the arcuate portion, the radius of the circular parallel mating means being equal to that of the groove of said nut and having its axis located beyond the arcuate portion at a distance substantially equal to one-third the radius of said circular parallel mating means to provide the maximum strength to both nut and wrench, and having a band secured to the sides of said wrench to completely encircle the remaining portion of said nut which is not encircled by the arcuate portion of said wrench.