SE180464C1 - - Google Patents

Description

Inventor: H G Mitenchinger Priority May 5, 1959 (USA) The present invention relates to threaded screws, in particular screws with recesses in the screw head of the type known as cross-spare screws, bolts and the like.

Crossed screws of the cross-section type, which are provided with recesses in the screw head for engagement with a tool, have advantageously been used all over the world. The special recess has been improved during later Lid, in that the conicity of the recess has been reduced, thereby reducing the risk that the retractor tool will be pushed out in the axial direction, as large torque is applied, and thus greater torque can be applied before such expression takes place.

A star application has the so-called cross-spar recess in connection with self-tapping screws, ie. screws, lamped to be used In metal, plastic or other material, ddr a previously drilled hall is threaded during the tightening of screws, which are provided with threaded threads or -ander. Dangerous use of self-tapping screws requires that these exhibit certain important characteristics of the recess, including the following: I. be able to transmit a large tightening torque, the tightening tool must be able to be inserted, maximum stability of the pulling tool in the recess.

In addition, in order to obtain commercial success, screws provided with recesses having the said markers must be able to be manufactured by the usual two-stroke upsetting method. Delta meant that one spirit on part of the wire or other material of which the screw is made is upset, while it was placed in the sink in the upsetting machine, first by means of a tool which forms an upset on the spirit of the blank and then by means of an additional tool. which finely shapes the screw head and the recess therein for engaging the screwdriver. Denim work operation is performed automatically and at star speed.

Through experience Iran the manufacture of many millions of cross-spare screws Or part edge, that an exact match can not Lippnas radian material in the screw housing and mandrel that forms the recess, if one does not apply a positive, Food directed, radial pressure, as occurs in the manufacture of screws with countersunk head, sleeve head, etc. When punching the recess in other types of screw heads, which are generally called single-tapered heads, a phenomenon, called material loss, is always encountered. Screws with non-countersunk heads manufactured according to the two-stroke shearing method are used without comparison mostly as self-tapping screws. Such screws with non-countersunk heads can be of the type kanda under the designations screw with ball-shaped, ball-shaped cylindrical, ball-shaped conical or cylindrical head and I. ex. have heads, the bottom surface of which lies in a plane at right angles to the axis of the screw. In the manufacture of screw heads with recesses of this type, the use of positive, inwardly directed, radial pressure is not possible. As mentioned above, on the other hand, the self-propelled embodiments require the greatest tightening torque and maximum stability of the driver, which can of course be related to each other. In other words, the tightening tool must be able to emit a large torque without throwing in the recess. Here .. this combination of pitches has been practically impossible to achieve, due to the fact that the increased torque transfer shape required a recess, the driving side surfaces of which would be almost parallel to the axis of the screw. However, parallel or almost parallel driving side surfaces eliminate the possibility of using a wedge fit between the tightening tool and the screw, which is required to achieve stability of the driver. The problem is further complicated by the pharyngeal loss phenomenon in the sprain operation as previously mentioned.

The degree of material loss in the manufacture of non-countersunk head screws varies depending on the hardness or type of material being spun, the proportions (d-vs: the ratio between the largest diameter of the recess and the diameter of the central deli of the recess and the depth of the recess). delay, which does not necessarily follow a linear formula, for an ice shape at the recess, approaches a critical point, beyond which only small change occurs.The omission causes a curved surface, which begins at a point, bela.gen ph about half or two thirds of the distance to the bottom of the recess, ie a fairly good adhesion between the metal and the mandrel is found in the lower part of the recess.Against the first impression, this condition has an all-in detrimental effect on the stability of the recess.A good fit for the recess in the recess bottom turning point, around -which the player throws due to too large play yid recess even upper surfaces.

In addition, during the upsetting operation, a wear of the upsetting mandrel near its tip takes place, which results in a reduction in the size of the recess in the lower part with a correspondingly smaller penetration of the driver as follows. This condition further confuses the problem of questioning the tosser's throw in the recess. This throw is particularly difficult, since the tightening of the screw in the workpiece must be drilled, since the axial force applied thereby causes the screw to strain to "bend off" from the driver, unless it radiates good stability. Instability between the screwdriver and the screw therefore entails major disadvantages during operations in assembly lines of this shell and due to reduced torque transmission capacity.

The loss of material during the punching of screw heads provided with a recess has two lasers, namely «plug plug and« extension ». The first is Iran's the outward movement energy, which is given to the material in the screw head by the blow from the penetrating mandrel. The "extraction" on the other hand depends on the ratio between the maximum and minimum diameter of the recess and the "extraction" becomes larger the larger this ratio. In other words, when making a recess in which the radial extent of the grooves is several times larger than the radius of the central part of the recess, the metal in the sectors between the grooves will be pulled out to a considerably larger extent than for a recess in which the radial extent of the grooves hr only slightly larger than the radius of the central part of the take-off. This depends on an effect which can be roughly compared to the effect of the expansion in a liquid a.

Careful examinations have shown that the chord angle of the hook through the material loss is 0 to 0 towards the axis of the screw. However, this loss can not be eliminated by increasing the vertical angles of the recess and the corresponding mandrel, since this would increase the above-mentioned ejection component, which in turn limits the torque transfer capacity of the screw-screwdriver combination.

The present invention largely solves the problems arising from the above-mentioned "failure phenomenon" by providing a recess in which the ratio between the radial extent of the recess and the central part of the recess is reduced by arranging one or more grooves between each pair of adjacent recesses in the place of the conventional one. angular or curved boom. In addition to improving the above-mentioned relationship and thereby reducing the "extraction" of the material during the punching operation, the arrangement of said grooves entails an improved torque transfer shape by obtaining extra surfaces for driving contact between the screw recess and a corresponding puller tool.

An object of the present invention is therefore to provide a threaded screw with a recess, intended for engagement with a retractor tool and extending from its upper end, its longitudinal axis comprising a central part and grooves projecting therefrom, the cradle in said central part between each pair of adjacent grooves or designed so that one or more grooves are provided from the upper spirit of the screw to the bottom of the recess, which raffia or grooves are laterally provided with substantially axially extending contact surfaces, intended to engage the puller tool. Some or all of these extra surfaces for engagement with the tool may tilt food, ie. have a conicity downwards towards the shaft of the screw. The aforementioned grooves suitably have a substantially triangular shape in the horizontal section and have a decreasing cross-sectional area.

A further object of the invention for providing a screw, provided with a recess in the screw head of the type defined in the preceding paragraph, in which the surfaces for engaging the pulling tool in each of said grooves intersect in a line which slopes downwards towards the shaft of the screw at an angle greater than approx. 10 ° and a maximum of approx. 14 °. However, such surfaces for engaging the tool do not need to intersect at an acute angle. If a plurality of grooves are arranged between the grooves in each adjacent pair, they may lie together or may be separated by an intermediate child of crooked or angularly serpentine cross-section.

Nanurda grooves will preferably extend from the upper part of the screw head to the recess of the recess, i.e. to the Association Plan for the savings and the central part of the recess. If desired, the grooves can be reduced to zero at a point above the said plane.

Another object of the invention is to provide a tool as a complement to the recess described above, which tool can either be a mandrel for forming the recess in a sprained screw or a tightening tool which cooperates with the recess in the application of a screw in a workpiece. The mandrel and retracting tools of the present invention may, of course, vary in the respects which have been pointed out in connection with the recess.

Other and further objects, features and advantages appear from the following description, which gives, with reference to the accompanying drawings, in which Figs. 1 and 2 illustrate the previous embodiment and show in two and three parts, respectively. longitudinal section a screw, provided with a recess in the head, in which recess the tip of a retractor tool Or is inserted.

Fig. 3 Or a cross-section of a screw head, provided with a recess according to the invention, in which recess the tip of a screwdriver tool Or is inserted.

Figs. 4, 5 and 6 Concern sub-sections along lines 4-4, 5-5 and 6-6 of Fig. 3.

Fig. 7 is a plan view of a modified recess according to the invention.

Figs. 8 and 9 Concern sub-sections along lines 8-8 resp. 9-9 in Fig. 7.

Fig. 10 is a plan view of a further modified embodiment of the recess according to the invention.

Fig. 11 Or a partial section along the line 11-11 in Fig. 10.

Fig. 12 is a plan view seen from below of a mandrel according to the invention for forming the recess according to Fig. 3.

Fig. 13 Or a side view, partly cut, of the mandrel according to Fig. 12.

Fig. 14 is a side view of the tip of a retractor tool corresponding to the recess of Fig. 3.

Fig. 15 Or a view of the tool according to Fig. 14.

Fig. 16 Is a view similar to Fig. 12 but as ash-like a mandrel lamped to form the recess according to Fig. 10.

Fig. 17 Or a view similar to Fig. 13 but as an ash mandrel according to Fig. 16.

Figs. 18 and 19 show ash in a duct view and a side view, respectively, of the tip of the tightening tool corresponding to the recess according to Fig. 10.

Fig. 20 is a view similar to Fig. 12 but which damages a mandrel, which corresponds to the recess according to Fig. 7.

Fig. 21 is a view similar to Fig. 13 but showing the mandrel of Fig. 20 and Figs. 22 and 23 as a side view of the retracting tool tip, respectively, corresponding to the recess of Fig. 7.

In order to facilitate the understanding of the invention, reference has been made to embodiments thereof, which are shown in the accompanying drawings and are described with reference to the same. No limitation of the invention has of course not been intended thereby and various changes and modifications may occur.

Referring to Figures 1 and 2, the screw head 10 is provided with a recess 11, which is usually made by cold pressing, which recess is typical of such recesses, which are derived from the commercial manufacture of screws with recessed heads. As can be seen from Fig. 2, the material in the head has fallen off during the punching operation, shown at 12, to such an extent that the cord 13 to the corresponding hook forms an angle of 10 ° to 15 ° with the axis 14 of the screw. shown somewhat exaggerated in Fig. 2. This drop-out phenomenon occurs during the formation of the recess qualitatively, although the joke is necessarily quantitatively quantified in the ascetic word. In the usual case, the noticeable dropout begins at one point, coated on half oil on two. thirds air depth of recess, matt from recess batten. The result is a clang fit for the tightening tool 15 in the recess, which makes it possible for the tool to throw considerably, especially when the necessary axial pressure against the dosing spirit is applied to keep the puller in engagement with the recess, while the tightening of the screw in the workpiece is drilled. In addition to the throw, the ash-damaged combination of recess and puller has the disadvantage that the torque transmission capacity is reduced. As can be clearly seen from Figs. 1 and 2, this torque transfer shape is further affected by the reduction of the contact surfaces on the tightening tool and the removal of the screw where the drive takes place.

Figs. 3 and 6 show a screw head provided with a recess 16, a challenge in accordance with the present invention. Fig. 3 also shows the tip ph of a traction tool 171 cross section. The recess extends into the upper spirit of the screw head 10a along the longitudinal axis 14 of the screw and consists of a central part 18, which base is shown in Fig. 4 and four spaced apart angularly spaced, substantially radial grooves 19, which extend outwardly. the central part 18. A radial groove 19 Or shown in vertical section in Fig. 6.

Between the usual pair of grooves 19 Or the rag in the central part 18 is designed so that an elongated raffia 20 is formed with side surfaces 21 and 22, which intersect in line 4-2. 23. Each of the raffles 20 extends neatly from the head. 10a upper surface to the plane at which the recess 19 intersects the central part 18 of the recess. The central part 18 is suitably terminated at the bottom with a substantially conical depression 24.

Each of the side surfaces 21 and 22 of each raffia 20 is inclined to the axis of the screw at such an angle that their line of intersection 23 has an inclination of between 0 and 15 ° to the axis of the screw. This line of intersection, which represents the bottom of the raffle 20, can thus be inclined at approximately the same angle as the natural angle of displacement in the material from which the screw is made, and in this way the material loss near the bottom of the raffle 20 is completely or substantially compensated. A tightening tool designed on a corresponding salt must fit snugly in such a recess, at least near the bottom of the grooves, all the way from the top of the recess to its bottom, thereby promoting good stability of the tool in the recess. Due to the reduction of the ratio between the largest and smallest radii in the recess (1 each plane, normally towards the axis of the screw!), The pull-out effect in the tilting operation is reduced considerably with the result that the only noticeable material loss slides along bars 25, which separate the grooves 20 from the grooves 19 The loss in these surfaces is quite insignificant, which means that large parts of the side surfaces 21 and 22 can be used for precise contact with corresponding surfaces on a driving tool, whereby the contact surface when driving between the tool and the screw is significant. The overall result of this improvement of the design of the removal of the screw and the corresponding tightening tool means that the stability of the combination of screw and puller is considerably improved and that the torque transfer shape is significantly reduced both for tightening and loosening. A comparison between Figs. 1, 2 and 3, 4 clearly damages this overall result. each raffia 23 (Fig. 3) and corresponds The puller extends over the entire depth of the recess in contrast to the surface shown in Figures 1 and 2, where there is no contact between the puller and the central cracks of the recess above the third of the recess.

Referring to Figs. 7, 8 and 9, the screw head 10b is provided with a recess 30, which differs from the recess 16 in Figs. 3-6, in that they had the grooves 31 arranged between the grooves 19 in each proximal pair. Each raffia 31 is bounded by side surfaces 32 and 33, the surfaces 33 being planar, which are substantially parallel to the screw shaft 14, while the surfaces 32 are planar, which are inclined inwardly and neatly towards the shaft 14. The raffles 311 of the ashless embodiment are separate apart from a boin 34, which is bounded by wide intersecting flat surfaces 35 and 36. If so Wed, however, the height of the booms 34 can be reduced by increasing the size of the air grooves 31, or the booms can be completely eliminated by inserting additional grooves between in both cases the advantages according to the invention, which are described in connection with the embodiments according to Figs. 3-6, are at least partly expressed, since the effect of the material loss will be largely completely compensated in the vicinity of the bottom of the raffles and the total driving contact surface. in the recess will be Ras.

Figs. 10 and 11 show a further modification, in which the screw head 10c is provided with a recess 40, which differs from that shown in Figs. 3-6 in that the flange 20 'between each pair of adjacent grooves 19 decreases in depth and cross-sectional area to a zero value at a point above the plane in which the groove 19 joins the central part of the recess 18. The bottom of the grooves 20 'is inclined towards the axis of the screw! 14 with an angle air between 0 and 15 ° as before, while the angle of inclination of the lower parts of the cradles in the central part of the recess has the conventional value of about 5-7 °. The modifications, ashless 111g. 7 resp. 10, can of course be combined with a simple recess if desired.

Figures 12 and 13 show a mandrel for forming recesses, intended for the production of recessed screw heads according to Figures 3-6. The mandrel comprises a body 50 of pd suitably salt hardened steel, provided with a concave recess 51, which corresponds to the desired convex shape of the upper side of the screw cap. In the present example, the recess 51 is substantially semi-dangerous. The tip 52 of the mandrel is integral with the body 50 and concentric therewith and with the concave recess 51. The tip 52 corresponds exactly to the recessed hole shown in Figures 3-6, which is described in connection with these figures, except for the surface of the recess. 25, in which an insignificant loss of material occurred during the formation of the recess. The side surfaces 53 and 54 of each horn 55 coincide with the adjacent surfaces 56 and 57 of the flanges 58 to form a curve with a relatively small radius, so that the surfaces 53 and 54 become substantially completely flat.

The retracting tool shown in Figs. 14 and 15 comprises a rod 60, shown cylindrically in the present example, and a shaped tip 61, which from the transverse plane shown at 62 to the duct 63 is exactly equal to the tip 52 ph dolmen, as shown in Figs. 12 and 13. Such a tightening tool will of course have a substantially complete engagement with the recess shown in Figs. 3-6. A comparison between Figs. 1 and 3 shows that the carrier according to the present invention has a considerably much larger transverse section than a conventional carrier, whereby the number of carrier fractures is reduced and the torque transfer capacity of the carrier is increased. The improved stability of the driver in the recess makes it possible to perform these with engaging surfaces, which are more parallel to the axis of the screw than was previously considered practically feasible, which further increases the torque transmission capacity. As mentioned earlier, this is especially important for self-propelled designs.

The mandrel ascased in Figs. 16 and 17 comprises a body 70 provided with a Lionkav recess 71 and a tip 72, which Or is designed to make the recess shown in Figs. 10 and 11 and which differs from this recess only in the same with respect to the mandrel according to Fig. 12 differs from the recess according to Fig. 3, namely in that the recess shows a certain insignificant loss of material in Iran the parts of the mandrel which side surfaces 73 and 74 on the booms 75 coincide with adjacent cradles 56 and 57 on the flanges 58. The tightening tool shown in Figs. 18 and 19 comprises a hose 80 of preferably hexagonal shape and a tip 81, which from the plane 82 to the duct 83 is formed in exact conformity with the tip 72 of the mandrel shown in Figs. Such a tool has an almost completely driving engagement with the contact surfaces in the recess according to Fig. 10.

The mandrel ashed in Figs. 20 and 21 comprises a body 90 with a concave recess 91 and an integral portion of the body 92, which is a substantially exact equivalent to the recess of Fig. 7, which is described in connection with this figure. , where the only important difference is due to an insignificant loss of material, which can occur in the upper part of the surfaces 35 and 36 in Fig. 7, which otherwise correspond to the surfaces 93 and 94 in Fig. 20.

The tool shown in Figs. 22 and 23 In this embodiment also consists of a hexagonal rod 100, provided with a one-piece challenge tip 101. In the case of the pull-in tool, the shaft may have a cylindrical, hexagonal or other suitable cross-sectional shape. The tip 101 of the present tool From the transverse plane, shown at 102, to the groove 103, is the exact equivalent of the tip 92 of the mandrel of Figs. 20 and 21. Such a tool, of course, fits substantially exactly into the recess which is damaged in Fig. 7. -9.

Claims (2)

Patent claim: A threaded screw, in its upper spirit provided with a recess intended for engaging a retractor tool, which extends the longitudinal axis of the flange screw and comprises a central part and a plurality of this radiating groove, which stand. at a certain angle relative to each other, kanneteanad of the fact that the cradle in said centers, lay part between each adjacent layer spar pairs Or designed so that a raffia is achieved frail said Upper spirit to the bottom of said recess, which raffia Or laterally bounded by substantially axially stretching engagement surfaces for the retractor tool and has a decreasing cross-sectional area. Screw according to claim 1, characterized in that at least one of said engaging surfaces Or is conically inclined towards said shaft. 3. A screw according to any one of claims 1 and 2, characterized in that said raffia has a substantially triangular horizontal section and a decreasing cross-sectional area. Screw according to any of the claims patent claims 1-3, characterized in that said engaging surfaces intersect in a line which slopes downwards towards said axis with an angle stone On 10 ° 5. Screw according to any one of the patent claims 1-3, marked by that said engaging surfaces intersect in a line, which slopes downwards towards said axis with an angle of e: a 14 °. Screw according to claim 1, characterized in that two of said grooves are arranged between each pair of adjacent grooves. Screw enlist patent claim 6, characterized in that each of said grooves Or arranged arranged next to one of the grooves in said pair of grooves and that said grooves are separated by a child. Screw according to claim 3, characterized in that said cross-sectional area decreases to zero at a point above the bottom in said central part of the recess. Screw according to patent claim 1, Urine characterized in that said grooves are arranged between the grooves in each pair of adjacent grooves. Tools for and removal of screws with recessed heads according to patent claim 1 and consisting of a core formed with a shaft part and a tip with flanges radiating therefrom, characterized in part by the fact that the cradle of said core between adjacent flanges Or formed with a child , which extends from the shaft part towards the spirit of the tip, and partly from the fact that the boom has mainly a triangular section and a cross-sectional area which decreases towards said tip. 11. A tool according to claim 10, characterized in that said bore Or is laterally defined by surfaces which are inclined conically inwards towards said tip. A tool according to claim 10, characterized in that two of said barriers are arranged between each pair of adjacent coated flanges. 13. A tool according to claim 12, characterized in that each of said bores Or is arranged adjacent to one of the flanges 6-- - in said pair, said booms being separated by a raffia. A tool according to claim 10, characterized in that the cross-sectional area of said child decreases to zero at a point near said tip. A tool according to claim 10, characterized in that a plurality of said bores are arranged between each pair of adjacent coated flanges. 16. Tool for forming the recesses In the screws according to claim 1 and consisting of a tool body and a tip, formed at one end of the body and with a terminating portion, where the body has a concave hook, so that a substantially semi-dangerous concave recess is provided therein. and said tip is connected to the body centered in the concave recess, can be shown that said tip comprises a central core and flanges radiating therefrom, the cradle of the core between adjacent flanges being shaped so as to form a child extending from said body. to the outermost end of the tip, which child is of substantially triangular section and with a cross-sectional area decreasing towards said tip. 17. A tool according to claim 16, characterized in that rd. of said barriers are arranged between each pair of adjacent flanges. A tool according to claim 17, characterized in that each of said booms is arranged adjacent to a flange in said pair and that the booms are separated by an air raffia. 19. A tool according to claim 16, characterized in that the cross-sectional area of said child decreases to zero at a point near said spirit. A tool according to claim 16, characterized in that a plurality of air bores are arranged between each pair of adjacent flanges. Request publications: Stockholm 196 2. Kumgl. Boktr. P. A. liorstedt & Sullen 620089