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Production produce self-tapping screws, screws

Production produce self-tapping screws, screws

CARL H. Robertson Mfg. This invention relates to screws of the type which are adapted to be threaded into untapped holes, and the object of the invention is to provide a screw which can be driven into untapped holes with greater facility and less driving torque than previous screws of this type. Another important object is to provide a screw as aforesaid which can be driven with a minimum requirement of driving torque into a blind hole provided for example, in structural and lower carbon content steel members, zinc or aluminum die castings, or brass or bronze forgings or the like, and which will swage form a thread formation on the wall of the untapped holewithout chipping of the wall surface so that the screw can be run clear to the bottom of the hole. Still another and important object is to provide a screw as aforesaid which will be self-locking against removal unless deliberately removed with a driver. In this connection, one important application of the invention is to provide a screw for holding two members together without requiring the use of a nut, the screw passing through a clearance hole in the upper member and entering an untapped hole in the lower member to swage form threads therein in a manner to provide a self-locking action.

VIDEO ON THE TOPIC: Self-tapping vs Self-drilling Screws

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Gabbey, P. Box , Los Angeles, Calif. Field of the invention This invention relates to locking fasteners. Description of the prior art In recent years, particularly for use in fields such as aircraft and missiles, increasingly stringent requirements have been laid down for threaded fasteners. High-performance bolts and screws now are made of stainless steels and new alloys of exceptionally high tensile strength.

Frequently, the fasteners are subjected to elevated temperatures, and may be heated to well above F. Very close tolerances are allowed between mating parts. Specifications permit no scratching or thread distortion sutficient to affect the thread efficiencies. This is despte the fact that the fasteners frequently are made of materials which tend to gall when mated. These requirements have made more difiicult the problem of providing a lock arrangement to prevent loosening of the fasteners.

Plastic inserts are not usable because of the temperatures encountered. Whatever the thread-locking design, a significant decrease in the strength of the fastener cannot be tolerated.

Consequently, the locking arrangement cannot remove much material from any portion of the bolt or screw, because to do so would lower the strength of the fastener. Specifications generally require reusability of the fastener, typically requiring that the fastener be mated and unmated times without reducing below specified torque values.

Some thread-locking arrangements are satisfactory initially but fail in the reuse tests, being worn by mating and unmating such that the locking eifect largely is lost.

By this process, the bolt shank is provided with a resilient localized outward bulge on the threads that presses the opposite side of the bolt into tight wedging engagement with the mating threaded opening.

The friction thus produced prevents loosening of the fastener. The localized bulge is produced readily and economi- 3,, Patented July 1, cally by a rolling operation when the threads are formed on the bolt shank. To this end, the dies for rolling the threads are provided with a small recessed area. When the screw blank is rolled between the dies to produce the threads, 9. After this, a small longitudinally directed hole is drilled in the end of the bolt shank adjacent the bulged portion.

This provides the bulge with resilient characteristics. In order to provide for sufficient material to produce the bulged portion, the blank may be contoured such that this is an added amount of material at the portion which is to be deflected into the recess in the die. In producing the recess in the die, the die blank first may be given a transverse slot by a milling cutter, and.

An object of this invention is to provide an improved method of producing a thread-locking arrangement. Another object of this invention is to provide a simplified method for producing self-locking bolt and screw threads to close tolerances. A further object of this invention is to provide a method for producing a self-locking male threaded member which may be made from high tensile strength material and which will not cause galling or become galled upon assembly.

Yet another object of this invention is to provide a method for producing a self-locking threaded member capable of reuse without sacrificing its locking characteristics.

An additional object of this invention is to provide a method of producing a self-locking threaded member that is not adversely affected by elevated temperatures. These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawing. FIGURE 4 is an exploded perspective view of the components utilized in making the die having a recess;.

FIGURE 6 is a side elevational view, partially broken away, showing the forming of the bulged portion of the threads of the fastener;. FIGURE 7 is a side elevational view of a blank used in forming a threaded fastener in accordance with the teachings of this invention;. FIGURE 13 is a side elevational view of a further modification of the blank for forming the threaded fastener;. FIGURE 11 is a side elevational view, partially in section, of a modified form of the blank for forming the threaded fastener;.

Extending longitudinally for a substantial portion of the length of the shank 11 is a localized outward bulge 13 on the threads. Generally, it is preferred to leave the two end thread convolutions 14 and 15 in the standard shape without the bulge 13 to facilitate entry of the shank 11 into the mating part. A longitudinally extending hole 16 is drilled in the shank 11 adjacent the bulged portion The opening is drilled inwardly from the shank end to a depth such that the opening parallels the entire length of the bulged portion.

The opening 16 is off-center from the axis of the shank 11 and made relatively small. Very little material of the shank is removed because of the small size of the aperture 16, so that the strength of the bolt or screw is not diminished materially.

The presence of the opening 16 provides the bolt shank with a relatively thin wall adjacent the opening and imparts a resilient characteristic to the bulged portion Thus, because of the thin wall resulting from the aperture 16, the bulged portion may be deflected inwardly toward the axis of the shank 11, and then will spring back to its original shape. As a result of this construction, when the shank 11 enters a mating threaded opening, the outward bulge 13 bears against the wall of the opening and pushes the shank 11 laterally toward the opposite side.

This wedges the threads on the side opposite from the bulge into firm engagement with the threads of the mating opening at that location. Consequently, greater torque is required to rotate the bolt or screw relative to the mating part, and a locking elfect is realized.

The fact that the bulge 13 is resilient not only enhances the locking action, but also means that it will not become worn unduly from repeated use of the fastener, so that the locking effect is retained. Moreover, the parts do not become galled when the fastener is mated and unmated. The threads are produced on the part through a rolling operation, as illustrated in FIGURE 3, which produces a threaded part within close tolerances.

Thus, the screw blank is turned between dies 18 and 19, which have opposed surfaces provided with V-shaped grooves that result in the production of threads on the shank.

Normally, flat dies are employed, although curved or circular dies also can be used. The die 18 may be conventional in contour. The die 19, however, has a recessed portion into which the shank is extruded in forming the bulge The die blank is a rectangular-shaped piece of metal having a flat upper surface In this surface is cut a relatively narrow transverse slot 22 having a length 4 less than the width of the die blank.

The slot 22 has parallel side edges 23 and 24 and a flat bottom surface 25 parallel to the outer surface In addition, there are provided a shim 26 and an insert These members are complementary to the slot at their edges and together fill the slot 22 when introduced into it. Thus, as seen in FIGURE 5, the fiat shim 26 and the insert 27 are placed into the slot 22, and the outer surface 29 of the insert is made flush with the surface 21 of the die blank.

After this, the V-shaped grooves 30 are formed in the surface 21 of the die blank in the conventional manner. The grooves 30 extend through the surface 29 of the insert 27 as well as the die surface Next, the shim 26 is removed, and the insert 27 is pushed downwardly against the bottom surface 25 of the slot The result is a shallow recess in the surface 21 of the die, with the thread contour being defined at the bottom of the recess.

Consequently, when the shank is rolled between the dies 18 and 19, a longitudinal portion of the shank will be extruded into the recess above the insert This produces the bulge When the shank of the screw is deflected into the recess, the grooves 30 in the surface of the insert preserve the thread contour so that the bulge resembles the remaining threads on the shank, but is distorted outwardly.

It is after the rolling operation that the opening 16 is formed in the shank The groove 22 is made shorter than the length of the shank of the blank used to form the bolt or screw Therefore, when the screw blank hangs downwardly between the dies 18 and 19 during the rolling operation, the lower end of the shank extends below the recess in the die As a result, this end portion of the blank is not extruded into the recess. Thus, the end thread convolutions 14 and 15 are made to the contour of the ordinary thread without the bulge.

In order to form a screw shank to close tolerances with a bulged portion included, there should be a provision for enough stock in the blank to permit the extrusion into the recess where the bulge is formed. Here, the screw blank 32 includes a first portion 33 of larger diameter than that of a shorter end portion When placed between the thread-rolling dies, the section 33 extends for a length corresponding to the length of the slot Therefore, as the blank is rolled between the dies, there is extra material at the part of the blank where the bulged portion is to be formed.

The amount of increased diameter in the section 33 is correlated to the depth of the recess and to the size of the bulge to be formed. As a result, there is just adequate material to fully enter the recess and form the bulge. The result may be seen in FIGURES 9 and 10, where longitudinal bulge 35 extends for the length of what originally was the portion 33 of the screw blank. End convolutions 36 and 37 are formed in the shorter and narrower portion 34 of the blank, which does not enter the recess.

Consequently, the end convolutions 36 and 37 are the same as the normal contour of the thread being produced. Here, the screw blank 38 has a cylindrical shank portion 39 of constant exterior diameter. However, there is a conical recess 40 extending longitudinally inwardly from the end of the section 39 of the screw blank.

This means that there is less material at the outer end of the blank than at the inner portions which are to be rolled into the recess in forming the bulge. The end portion, where the recess 40 is located, is compressed inwardly, substantially filling up the recess 40 as it is pressed between the normal die faces outwardly of the recessed portion.

In some instances it may be desired to have the bulged portions extend for less than the full length of the shank of the screw or bolt. Here, the blank includes sections 41 and 42 on either side of a larger portion The bulge will be formed for the length of the portion 43, while the sections 41 and 42 are given the normal thread contour.

Generally, the bulge on the screw shank is formed by a single die recess, as described above. It is possible, also, to form the bulge progressively by rolling the screw blank across recesses of gradually increasing depth in the die face. These recesses are spaced with relation to the diameter of the blank such that the same part of the shank extends across each recess as it is encountered.

Such progressive extrusion of the bulge is used primarily for screw blanks of particularly hard material. The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims. The method of producing a self-locking threaded member comprising the steps of rolling a screw blank of resilient material to produce a thread on the exterior thereof, rolling an exterior localized bulge on said threads,.

The method of producing a self-locking threaded member comprising the steps of providing die means with a pattern to produce a thread upon rolling of a blank against said die means, recessing a localized portion of said pattern of said die means,.

The method in accordance with claim 2 including in addition the steps of providing said blank with first and second portions with said first portion having more material than said second portion,. The method in accordance with claim 3 in which said second portion of said blank is provided at one end thereof. The method in accordance with claim 3 in which, for providing more material at said first portion than said second portion, said second portion is provided With recess means therein.

The method of producing a self-locking threaded part comprising the steps of providing a pair of opposed substantially fiat dies having longitudinally extending grooves therein defin- -6 ing a pattern for producing screw threads on a part rolled therebetween,. The method of providing a self-locking threaded member comprising the steps of providing die means with a pattern to produce a thread upon rolling of a blank against said die means, recessing a portion of said pattern of said die means, preparing a screw blank of resilient material so as to have a first portion of a relatively small amount of material and a second portion of a relatively large amount of material, then rolling said blank against said die means to produce a thread thereon with said second portion being rolled over said recess for deflecting material of said blank into said recess,.

US3452375A - Process for producing self-locking screw threads - Google Patents

The base material is wire. Since our example is a bi-met screw, the wire is made of stainless steel. The wire is coiled and thus needs to be straightened and cut to the appropriate length. In our example, it is a hexagon screw head. The upper part of the bi-met self-drilling screw consists of stainless steel so that it offers an ideal corrosion protection and can be used in weather-exposed areas.

Gabbey, P. Box , Los Angeles, Calif.

Paulo Davim received the Ph. He has guided large numbers of postdoc, Ph. He has received several scientific awards. He has worked as evaluator of projects for international research agencies as well as examiner of Ph. He is the Editor in Chief of several international journals, Guest Editor of journals, books Editor, book Series Editor and Scientific Advisory for many international journals and conferences.

China self-tapping screws screw

Refine your search Locate the companies on a map. We have vast stores of raw Contact this company. Manufacturer of tactile studs. For over 30 years, La Frappe Ardennaise has specialised in the cold heading of rivets, pins, hinges and screws. Standard rivets, milled head rivets, semi-tubular Goebel is a family-run, internationally active group of companies for fastening and installation technology. We consider ourselves specialists for developing innovative and high-quality fastening

18-8 Stainless Steel Self Tapping Screw

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They allow an efficient fastening on low-thickness metal materials; the presence of the tip helps to form the thread and to fit into the hole. The height of the low crest allows to perform deep screwings without cracking the materials. Compared with metal self-tapping screws, with the same diameter, they allow reduced pre-drills, with the advantage of strengthening the pieces.

Self-tapping screws for every application

Handan Daoning Fasteners Manufacturing Co. Company is located in northern China's largest fastener production base in Handan City Hebei Province. We have set up business relationship with professional customers in North America, Europe, Australia and Asia. We firmly hold our operational concept-"Sincerity, devotion, creativity, innovation", taking a quality-profitability development road under the guidance of scientific management, customer satisfaction, and supreme quality.

SEE VIDEO BY TOPIC: How Screws Are Made - Automated Factory Tour in China

The Stainless Steel Self Tapping Screw offers various sizes for customers to choose from, it can be customized as will. It is widely used for connection in aluminum alloy windows, doors, thin steel plates and so on. Product instruction. The head is well formed and the thread quality is high. It can not only reduce the workload of fixed engineering, but also has the characteristics of convenient to use, it is widely used in appliances and other products.


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Our range of self-tapping screws according to UNI / DIN standards. They allow an efficient fastening on low-thickness metal materials; the presence of the tip helps to form the thread and to fit into the hole.

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Multiform Fasteners Co. We are not only an OEM producer but also an original design manufacture ODM company producing high quality and innovative fasteners in Taiwan. Our products include a wide variety of wood screws, self-tapping screws, self-drilling screws, window screws, drywall screws, etc.

A self-tapping screw is a screw that can tap its own hole as it is driven into the material. Self-tapping screws have a wide range of tip and thread patterns, and are available with almost any possible screw head design. Common features are the screw thread covering the whole length of the screw from tip to head and a pronounced thread hard enough for the intended substrate , often case-hardened. For hard substrates such as metal or hard plastics, the self-tapping ability is often created by cutting a gap in the continuity of the thread on the screw, generating a flute and cutting edge similar to those on a tap.

The present invention relates to threaded fasteners and more particularly to a self-tapping screw and a method and apparatus for making same.

Стратмор задумался над ее словами, затем покачал головой: - Пока не стоит. ТРАНСТЕКСТ работает пятнадцать часов.

Пусть пройдут все двадцать четыре часа - просто чтобы убедиться окончательно. Сьюзан это показалось разумным.

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Я читал все его мозговые штурмы.

- Вы ждете рекомендаций. Что ж, пожалуйста. Хватит путаться у нас под ногами, вот моя рекомендация.

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  1. Dogal

    Your phrase is matchless... :)