FI68539C - REPAIR SCREW SAMT FOERFARANDE FOER FRAMSTAELLNING AV DENA - Google Patents

Description

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gUQ | ^ || __p || ^ | ^^ | ^ Q (21) Patent application - Patentansökning '(22) Application date - Ansökningsdag 2 * · · 0 1.78 (= ») (23) Start date - Giltighetsdag 2 * 4.01. / 8 (41) Has become public - Blivit offentlig 29.07.78

National Board of Patents and Registration Date of publication and publication. - 28.06.85

Patent- och registerst / relsen '1 Ansökan utlagd och utl.skriften publicerad (32) (33) (31) Pyydetty etuoikeus - Begärd priority 28.01 .77

German Federal Republic of Germany (DE) P 2703 * 433.9 (71) Wilhelm Schumacher KG, Am Preist 5, 5912 Hilchenbach 1, German Federal Republic of Germany (DE) (72) Ulrich Schumacher, Hilchenbach, Wolfchen, Wolfchen Wittmann, Hilchenbach,

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (7 * 0 Forssen & Salomaa Oy (5 * 4) Thread-forming screw and method of manufacture - Gängfor-Mande skruv samt förfarande för framstäl1 Ning av denna

The invention relates to a thread-forming screw, in which the threads rolled into the arm have a profile height formed by the raised or strip-shaped circumferential parts running in the longitudinal direction of the threads along the entire thread length, which is greater than the profile height of the adjacent circumferential part.

The invention further relates to a method of manufacturing a thread-forming screw, wherein the arm-rolled threads have a profile height formed by elevations in the longitudinal direction of the threads extending in the longitudinal direction of the threads along the entire length of the threads. and in addition the protrusions projecting radially from the threads are distributed around the screw along screw lines with a uniform steep pitch, and that each protrusion in the direction of the screw lines extends to a constant width of the pressure by means of grooved flat jaws in the thread rolling machine.

68539 2

Many different embodiments of threaded screws are already known, as can be seen, for example, in the "Assembly Engineering Master Catalog", Jahrgang 1975/76, page 358. It describes the differences between screws which form a thread by the cutting method, i.e. by cutting, and by which the thread is formed by the grooving method, i.e. without cutting.

Thread-forming screws which thread a pre-drilled hole without chipping by a grooving method are also known from German application publications DT-OS 24 61 546 and 25 50 817.

Most known thread-forming screws, which make threads in pre-drilled holes in the walls without cutting by the drilling method, have the disadvantage that they cannot provide any orthodontic thread, which would allow the screw to be screwed in even after the thread-forming screw has been unscrewed. Another disadvantage of most known thread-forming screws is that they require a relatively high torque and that the screw arms must be provided with a special profile with a polygonal cross-section completely different from normal screws in order to manufacture thread-forming screws. In this case, when the polygonal special profile extends over the entire length of the screw arm, as is the case, for example, with the screws described in the "Assembly Engineering Master Catalog", a substantially lower release value and excessive torque are generated compared to normal screws.

The object of the invention is to eliminate all the disadvantages associated with the described known thread-forming screws. It is therefore an object of the invention to provide a thread-forming screw of the type described above which can be manufactured as simply as a normal screw, but which nevertheless allows a correct thread to be made in the boreholes and by causing a lower tightening torque at each desired screw shank length. It is a further object of the invention to provide a method for simply manufacturing this thread-forming screw, as well as a rolling jaw for carrying out this manufacturing method.

The thread-forming screw according to the invention is mainly characterized in that the cylindrical screw arm has a circular core cross-section which is uniformly continuous over its entire length, that the radially projecting protrusions at a constant width along the threaded side of the thread in question and over the threaded tip and is formed in one piece with the threaded side and the threaded tip of the material of the screw arm.

The method according to the invention, on the other hand, is characterized in that a screw blank having a flat shank with a circular cross-section and a hardness of about 40-50 kp / mm is simultaneously rolled with threads and linear or strip-shaped protrusions with a higher profile height. by forming a cross-section of the heart, in which case flat jaws with a hardness of between 57 HRc and 60 HRc are used.

If the first threads at the free end of the shaft are not completely shaped, according to the invention a very soft screwing effect is achieved when the threads are provided evenly arranged around the arm circumference, line! with strip-shaped circumferential sections with a higher profile height. It has proved to be very expedient in this case that the threads are provided with four evenly spaced, lined! with a strip-like circumferential portion with a higher profile height.

It is also advantageous when, according to a further feature of the invention, the ascending direction of the helically circumferential portions with a higher profile height running helically around the arm circumference corresponds to the ascending direction of the normal thread, i.e. the right-hand thread has a right-hand thread and the left-hand thread has a left-hand thread.

In a highly preferred embodiment of the thread-forming screw according to the invention, the ratio of this nominal diameter to the rigidly helical helical circumferential parts having a higher profile height can be about 1: 9, i.e.

The method according to the invention for producing such thread-forming screws is characterized mainly by the fact that a screw blank having a flat shank with a circular cross-section and a hardness of about 40-50 kp / mm is simultaneously threaded and stripped or striped split protrusions with a higher profile height by forming a circular cross-section, in which case flat jaws with a hardness of between 57 HRc and 60 HRc are used.

In addition, it is advantageous from the point of view of the manufacturing technique that, when rolling the threads, the material displaced on the circumference is formed partly transversely to the thickenings or protrusions on the threaded sides.

In order to carry out this method in a rolling jaw, which jaw is provided with a groove profile corresponding to a cross-section, a plurality of recesses are arranged on the sides of the groove profile at regular intervals and mainly transverse to the longitudinal direction of the grooves. The lines or strips determining the location of the recesses in the rolling jaws are then arranged obliquely with respect to the longitudinal direction of the grooves.

In addition, according to a further feature of the invention, it is preferred that the recesses are formed to be recessed at least 0.025-0.075 mm with respect to the groove bases, so that thread rolling produces at least thickenings or protrusions in the thread tips with a thread diameter greater than in areas between thickenings or bumps.

Finally, in the rolling jaw according to the invention, it is preferred that the recesses are printed on the sides of the groove profile.

The invention will now be explained in more detail with reference to the drawing.

Figure 1 shows, in a much enlarged, perspective view, a screw blank with a flat, substantially cylindrical, but still thinned cone-shaped shank at its free end.

Figure 2 shows a section along the line II-II in Figure 1.

Fig. 3 likewise shows in a much enlarged perspective view 5,68539 a thread-forming screw according to the invention made using the blank of Fig. 1.

Fig. 4 shows a section along the line 1V-IV in Fig. 3.

Fig. 5 again shows, on an enlarged scale, a longitudinal section of the area of the thread-forming screw marked with the symbol V in Fig. 3.

Fig. 6 schematically shows in a simplified top view a rolling jaw such as that used to manufacture the thread-forming screw of Fig. 3 from the screw blank of Fig. 1 in a thread rolling machine.

Fig. 7 shows on an enlarged scale a part of the threaded jaw marked VII in Fig. 6.

Fig. 8 again shows on an enlarged scale a section along the line VIII-VIII in Fig. 7.

Fig. 9 shows a section along the line IX-IX in Fig. 7 in the manufacture of a thread-forming screw through two cooperating rolling jaws.

Figure 1 of the drawing shows a screw blank 1 from which a thread-forming screw 2 must be made, as seen in Figure 3. The screw blank 1 then has a shape which can also be used for making normal screws, , a screw part 5 having a circular cross-section, as shown, for example, in Fig. 2. The largest length portion 6 of this arm portion 5 has a cylindrical shape, while the free end of the arm portion 5 terminates in a truncated cone-shaped thinned end portion 7.

The diameter 8 of the cylindrical part 6 of the shank part 5 then corresponds approximately later to the central diameter 9 of the thread 10 rolled into the shank part 5, as can be seen by comparing Figures 2 and 4. The diameter 8 of the smooth shank part 5 is thus smaller than the outer diameter of the finished thread 10, but larger than the core diameter 12 of the shank part provided with the thread 10.

In order to roll the thread 10 into the flat shank part 5 to form the thread-forming screw according to Fig. 3, at the same time as the thread 10 is rolled, line-shaped or strip-shaped circumferential portions 16 are made of material-shaped thickenings or protrusions 16 on each side of the individual thread 15. , that in the region of these thickenings or protrusions 16 the shank part of the screw-forming screw 2 has a diameter which is e.g. 0.05 mm larger than the outer diameter 11 of the thread 10 forming the nominal diameter.

It can be seen from Figure 4 of the drawing that a plurality (e.g. four) of thickenings or protrusions 16 are evenly distributed on the shank circumference of the thread-forming screw 2, so that each thread 15 has a corresponding number of thickenings or protrusions 16. In this case, the individual threads of the thread 10 or the protrusions 16 are then arranged on the linear or strip-like circumferential parts of the screw arm, which run sharply helically around the circumference of the arm, as is clear from Fig. 3. The rising direction of the linear or strip-shaped circumferential portions formed by the thickenings or protrusions 16 running sharply helically around the arm circumference then preferably corresponds to the rising direction of the threads 15. This means that the right-handed thread 10 also has thickenings or protrusions 16 in the right-hand threaded circumferential or strip-down circumferential portions of the circumference, while the left-handed thread is in the left-handed threaded lines! in strip-like circumferential parts.

By screwing the thread-forming screw 2 according to Fig. 3 into a pre-drilled hole, thickenings or protrusions 16 on the individual threads 15 are formed by a so-called grooving method - i.e. without cutting - an orthodox thread into the bore walls to which the screw can be screwed on after unscrewing the thread.

By arranging the thickenings or protrusions 16 on the threads 15 in the form of a screw, a very soft screwing effect and a small tightening-tightening torque are created, although e.g. the first threads 15 in the truncated cone-shaped end part 7 are not fully shaped.

It is very advantageous in order to achieve a high release value and a large excess torque that the thread 10 runs substantially circularly I! 68539 around the arm circumference, as is the case with a normal screw. Thus, the screwed-in screw 2 completely fills the hole with the thread formed.

Furthermore, it is preferred that the shank 5 of the thread-forming screw 2 can theoretically be of the desired length, because the thickenings and protrusions 16 applied to the threads 15 on their sides and peaks 14 can be formed in the thread-rolling operation due to their relatively low material accumulation. In this case, the shaping forces generated by the threading jaws by means of the rolling jaws remain practically the same, because the thickenings or protrusions 16 do not all occur simultaneously, but when rolling the screw arm between the two rolling jaws. This advantage is due to the sharply helical position of the bumps or protrusions 16 in the longitudinal direction of the screw arm.

Otherwise, it is sufficient that the long screws are provided with a thread-forming profile only at the front area. The rest of the area may be equipped with a normal thread.

A threaded rolling jaw 18, such as that used to make the thread-forming screw 2 of Fig. 3, is shown schematically in Fig. 6. This rolling jaw 18 is provided along its entire length with a groove profile 19 slightly oblique to its longitudinal axis, which profile shape corresponds to a conventional thread.

An enlarged portion of the threaded rolling jaw 18 can be seen in Fig. 7. It can be seen that the threaded rolling jaw 18 has, in addition to the groove profile 19, molded recesses 20 formed on the sides of the groove profile 19 and a plurality of evenly spaced and substantially transverse grooves 21 along. The lines or strips 21 determining the position of the recesses 20 in the rolling jaws 18 are then preferably arranged obliquely with respect to the longitudinal direction of the grooves of the groove profile 19, and then at an angle 22, as shown in Fig. 6.

Figure 8 of the drawing illustrates how the recesses 20 are formed in the sides 23 of the groove profile 19. The recesses 20 terminate below the groove ridges 24, while they extend over the groove base 25 between the two adjacent sides 23 of the groove profile 19.

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The recesses 20 can be made in the sides 23 of the groove profile 19 in different ways. They can be milled, for example, on the sides 23 of the groove profile 19, in which case it must be noted that the distance 26 between the recesses 20 on two adjacent lines 21 must be accurately maintained, e.g. 0.01 mm, so that the bolt arm or the protrusions are formed on the sides 13 of the threads 15 properly.

It has proved very advantageous if the recesses 20 are pressed into the sides 23 of the groove profile 19 by means of a suitable tool. However, the shape and operation of the tool for making the rolling jaw 18 is not an object of the present invention.

Fig. 9 shows a manufacturing method for the thread-forming screw 2 according to Fig. 3. In this case, the screw blank 1 according to Fig. 1 is inserted between the two rolling jaws 18 of the threading machine. 5 perimeter. In this case carried out in the direction of the arrow shown ruuviaihio rolling movement between the two valssausleukojen 18, which takes place within the flat materiaalisyrjäytys periphery of the shaft portion 5, resulting in the thread 10, and at the same time also of the protuberances and the protuberances 16 consisting of individual threads 15 of the flanks 13.

For the manufacturing method 2 of the thread-forming screws 2 according to Fig. 3, a screw blank according to Fig. 1 with a hardness of about 40-50 kp / mm is used. On the other hand, rolling jaws 18 with a hardness of between 57 and 80 Rc are used.

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Claims (6)

1. Thread-forming screw, in which the threads (15) rolled in the shaft (6) in linear or band-shaped peripheral sections running longitudinally of the threads along the entire thread length have a profile height (17) formed by the humps (16) than in adjacent peripheral sections, characterized in that the cylindrical screw shaft (5) has a uniform circular core cross-section (12) throughout its length. that the humps (16), radially projecting radially from the threads, are distributed around the screw following screw lines with uniform steep pitch; and in that each hump (16) seen in the direction of the screw lines extends at a constant width along the threaded flank (13) and over the threaded tip (14) of the threaded thread (15) and is formed in one piece with the threaded flank (13) and the threaded tip ( 14) from the screw shaft material. Screw according to claim 1, characterized in that the threads (15) are provided with several, preferably four, linear or band-shaped peripheral sections (16) with a larger profile height (17), which sections are uniformly distributed around the shaft. Screw according to claim 1 or 2, characterized in that the screw lines, after which the humps (16) are distributed, have the same pitch direction as the threads. 4. A screw according to any one of claims 1-3, characterized in that the ratio between the nominal diameter (11) and the slope of the circumferentially extending sections with a greater profile height (17) at the screw is at 1: 9. A method of producing a thread-forming screw according to claim 1, wherein the threads wound in the shank (16) on linear or band-shaped peripheral sections running longitudinally of the threads after the entire thread length have a profile height (17) formed by the humps (16). ), which is larger than that of adjacent peripheral sections, the screw shank (5) having throughout its length a uniform circular core cross-section (12), and further the humps (16) projecting radially from the threads are distributed around the screw by helical lines. uniform steep incline, and so that each hump (16) seen in the direction of the helical lines extends at a constant width along the thread.