SCREW FOR SCREWING INTO PLASTIC.

Abstract

The invention relates to a screw (10) for cutting a matching thread in a plastic article, comprising a lower threaded portion (F) and an upper threaded portion (T), the lower threaded portion having a larger diameter and a tip covering a larger surface area than the upper threaded portion.

Description

SCREW FOR THREADING INTO PLASTIC The invention relates to a screw, in particular for screwing into plastic, of the type specified in the preamble of claim 1. US patent 5,795,120 B discloses a screw for insertion into a component having a pilot hole therein. The screw has a forming thread zone and a bearing thread zone, the thread profile in the forming thread zone being proportionally larger than the thread profile in the bearing thread zone. The disadvantage of this design is that, especially when the screw is used with plastic materials, a high load will act on the component if a larger pitch and a smaller flank angle for the screw are already considered. The objective of the invention is to provide a screw that has a low insertion torque but results in a low correlated load on the component and at the same time guarantees high extraction values. This objective is achieved. (ma di before the features) Characteristics of claim 1 together with the features of its preamble-, 5 The subordinate claims define advantageous further developments of the invention. In a well-known way, a screw has a shaft. central, a footprint and a threaded shank. The shank has at least one thread formed on it, the twist of which extends, at least partially, in a helix of constant pitch along the shank and thus forms a main thread of changing profile contour that has a mean thread radius along its length. The profile contour is defined by the cross-section of the thread in a section plane of the helix, the central axis of the screw being located in the section plane. The thread radius is the maximum orthogonal distance from the center of the thread to the center of the thread twist. The main thread has a bearing area and a forming area, the forming area having a contour of the forming profile of a radius of the forming area and the bearing area having a contour of the bearing profile of a radius of the bearing area. The formation profile contour is obtained by projecting the thread turn along the helix, particularly in the direction of the trace, onto an area that extends axially over a length three times the mean radius of the helix from the free end of the shank, onto a section of the helix plane, with the central axis of the screw in the section plane. Therefore, the projection corresponds to the projection of the linear unfolding of the thread turn onto a section plane of the helix in which the central axis of the screw is located. This results in a formation profile contour of a maximum extent that represents the effective formation profile contour. This formation profile contour has a maximum orthogonal distance from the central axis of the screw, which defines the radius of the formation area. The formation area ends at the helix point where the formation profile contour has its maximum extension closest to the footprint in the '851 range of the 2Q thread radius measured outwards in a radial direction before subsequent profile contours are again within the formation profile contour. The contour of the support profile is formed by the projection of the thread onto a helix section plane. -4along the helix, in particular in the direction of the footprint, over an area that is angled azially and that begins at a distance of 2 / 3 of the mean radius of the thread from the end of the area of ​​forrr ase i in and ends at 573 of the mean radius of the thread. This shape forms a partial area of ​​the bearing area. It can extend further along the main thread in the direction of the footprint, provided that the profile contour does not protrude beyond the bearing profile contour. This bearing profile contour has a maximum orthogonal distance to the central axis of the screw that defines the radius of the bearing area. This ensures that the transition area from the forming area to the support area is as short as possible and that the support area is long enough to allow the basic clamping function of the screw to be fulfilled. Furthermore, the contour of the support profile and the contour of the formation profile are adapted to each other in such a way that in the case of an overlap with the contour of the support profile and the contour of the formation profile along the helix, at least in the area that extends outwards in the radial direction of 83% of the radius of the formation area, the contour of the support profile is completely within the contour of the formation profile. This ensures that the elastic reaction of the material in the female thread formed can be taken into account and that a loose insertion can be performed. The invention provides that the contour of the forming profile delimits a surface of the forming profile which, measured at a range of 10% of the radius of the forming area, from the maximum orthogonal distance of the contour of the forming profile to the central axis of the screw radially inwards, is larger than the surface of the bearing profile delimited by the contour of the bearing profile, measured at a range of 10% of the radius of the forming area from the maximum orthogonal distance of the contour of the bearing profile to the central axis of the screw radially inwards. This matching of profile contours according to the invention allows compensation for elastic recovery in the female thread, even with relatively small flanging angles, ensuring sufficient flank coverage. This avoids damage to the component material, as caused by a screw with a thread forming area proportionate to a large thread. Preferably, the contour of the forming profile and the contour of the support profile have a flank angle of less than 35°. The flank angle of the forming profile contour is 130°. The sum of the two base angles gives a trapezoid formed because the bases of the trapezoid are constituted by the section lines parallel to the screw axis at 85% of the radius of the forming profile RF and at 95% of the radius of the forming profile RF. The base angles are the angles at the longer base of the trapezoid, that is, at the section line at 85°. Similarly, the same rule used for determining the angle of the flare also applies to the contour of the support profile, in which case the section lines are placed at 3% of the radius of the support profile R and at 95% of the radius of the support profile RT. The flank angle is found in particular between 20 and 30 degrees. This angle has proven useful for screwing plastic components. 2Q According to an improvement advantage of the invention, the radius of the support area is smaller, between 1% and 3%, than the radius of the forming area. This minimizes damage to the plastic composite material, but still allows a sufficiently large distance to be established between the contour of the forming profile and the contour of the support profile, which represents the elastic return of the material. It is especially advantageous that the contour of the bearing profile has an axial width at 95% of the radius of the bearing area that is less than the axial width of the contour of the forming profile at 95% of the radius of the forming area. This allows a simple design of the thread profile such that the surface area of ​​the forming profile is larger than the surface area of ​​the bearing profile. In particular, the width of the profile outline; support is less by at least 10%, in particular by at least 20%, than the width of the profile outline. To facilitate production, the outline of the forming profile and / or the outline of the support profile can be symmetrical. ,2G According to a particularly advantageous embodiment, the forming area is less than 2 times the pitch. Preferably, the thread rotation increases to its forming profile contour and remains in place, extending to the end of the forming area. Preferably, the ratio between the core radius and the mean thread radius can be between 0.6 and 0.8. These are common ratios for plastic screws. Furthermore, in another embodiment of the invention, the contour of the bearing profile, in the area extending radially within 85% of the radius of the forming area, may be at least partially outside the contour of the forming profile. This provides greater flexibility in the design of the flank-to-thread transition, allowing for greater consideration of the material properties. Additionally, the core diameter in the forming area is preferably less than or equal to the core diameter in the support area. According to another advantageous embodiment of the invention, the stem may have a threading cane at the free end of the stem of the drill string, said threading cane comprising at least 20 two turns of drilling thread, which are of a radius that is at most 90% of the radius of the formation area and which form a drilling pattern. The rosette of the cane is formed where the drill thread turns have the same diameter path and where, in addition, the rosette radius of the main thread is less than or equal to the thread radius of the drill thread turns. This is advantageous because it allows the screw to be positioned in a particularly straight orientation, meaning that the female thread cut into the plastic component by the subsequent forming area and the thread in the bearing area following the forming area are aligned as precisely as possible. This allows for the elastic recovery of the plastic material to be taken into account. As a result, the friction that occurs in the bearing area when the screw is inserted can be further reduced or even completely eliminated. Ptefefibléstente, the main thread in the drilling zone has: the same thread radius as the drill channel at the same axial distance from the free end of the screw shank. In this way* at least three identical threading points are created: by the, in particular two, turns of the drill thread and the main thread, which ensures a particularly straight orientation of the screw for drilling. Preferably, all threading turns in the drilling zone have their beginning in the same transverse plane. 10Furthermore, all thread turns in the drilled area have the same cross-sectional contour. This means they have an identical design. For example, the main thread and the two drilled thread turns start in the same way and have the same thread path. Alternatively, you can also: provide for the "three: threading turns: of drilling, in which case the threading radius of the main thread in the drilling zone is especially smaller than the radius of the drill rod. According to an advantageous embodiment of the invention, the threading turns begin at the core, with the radius of the threading turns continuously increasing from the core 15 to the end of the drilling zone. This ensures continuous and uniform orientation of the screw for drilling. Furthermore, the threading turns with the same thread radius can be distributed evenly around the circumference at the same axial height in the drilling zone. This ensures a symmetrical fit with the pilot hole in the plastic component. In particular, the diameter of the free end of the screw is at least 20%, at least 30%, at least 40%, at least -11 hí)%, at least twice the radius of the formation area. Such a blunt tip is common in plastic screws. The drill rod can immediately follow the free end of the screw. This ensures ideal screw guidance, as the screw is initially applied for drilling. Alternatively, the drill rod can be positioned at a distance from the free end of the screw. In this way, the area extending towards the end of the screw can serve as a locating tool. To facilitate production, the drill casing and main thread can be rolled threads. According to another advantageous embodiment of the invention, the threads in the drilling zone can have a more obtuse flank angle than the main thread outside the drilling zone. This is advantageous because it provides a centered thread of the entire thread without the drill thread turns hitting the material unilaterally, and also facilitates repeated assembly operations. -12Drilling re-turns can end abruptly at the end of the drilled section. This has the < »' *um rnr .+. friction as the screw is screwed further into a narrow pilot hole, 5 According to Otra, a more auspicious embodiment of the invention, the rat je ge*rof- obu can - + - cnuet se .^cb: e ut raxt no dv 3 / c turns. This makes the screw connection efficient, while also guaranteeing optimal screw orientation. In a drilling turn there may be interruptions in drilling turns, however, the interpolated course of the drilling radius remains the same. According to another aspect, the invention relates to a method for making a screw connection comprising a screw, according to the invention, of the type described above. For this purpose, the screw according to the invention is threaded into a pilot hole made in a plastic component, its forming area thus creating a counter-thread or a female thread that has the contour of the forming profile in the plastic. As soon as the counter-thread is no longer engaged with the forming area, it will spring back into the bearing area to reliably prevent the female thread from coming into contact with the thread in the bearing area when the screw is inserted. 13icsca in the support area will only be pressed against the counter thread when the screw is finally tightened into the component. Preferably, the screw is screwed into a pilot hole that has a radius of approximately 80% of the radius of the forming area. Furthermore, the invention relates to a screw connection produced according to the method described above. Additional advantages, features, and possible applications of the present invention can be obtained from the following description, in which reference is made to the embodiments illustrated in the drawings. In the drawings: Figure 1 is a side view of a screw according to the invention. Figure 2 is a perspective view of the unfolded thread turn. Figure 3a is a perspective view of the unfolded thread turn 3 times. Is Figure 3b a front view of the displaced thread turn? Figure 3u is a view of the contour of the forming profile obtained from the projection of the unfolded thread turn. Figure 4 is a perspective view of the unfolded screw turn showing the sun ad f.nn.iun. Figure 5a is a perspective view of the unfolded screw turn in the support area; Figure 5b is a front view of the unfolded scratch turn. Figure 5c is a view of a support thread contour obtained by means of a projection. Figure 6 is a view of the superposition of the forming thread contour of Figure 3c and the support thread contour of Figure 5c; -15“ Figure 7 is an enlarged view of an overlay illustrated in Figure 8. Figure 8a is a surface view of the 5-formation profile; Figure 8b is a view of the surface of the support profile♦ Figure 9 is a view illustrating the flahco- angle of the formation profile·:; Figure 10 is a view of the superposition of a contour of the formation profile and a contour of the support profile; Figure 11 is a view of the superposition of a formation profile outline and a support profile outline; Figure 12 is a side view of a screw with a perforation according to the invention. Figure 13a is: an enlarged view of the ge 25 perforation zone illustrated in Figure 1 / . - list figure 13b. It is a cross-sectional view through the ρ erioration zone. Figure 13c is another cross-sectional view av - - o^ ,,Je :v' ή * . '; Figure 13d is a cross-sectional view through the screw shank outside the drill hole* Figure 14 is a cross-sectional view of a screw thread according to the invention. Figure 15a is an enlarged view of the area of ​​the forming thread illustrated in Figure 14. Figure 15b is an enlarged view of the support thread area illustrated in Figure 141 Figure 1 is a side view of the screw 10 according to the invention, comprising a central axis 11 of the screw, a thread 12, and a threaded shank 14. Hereafter, the direction along the central axis M of the screw shall be referred to as 11. The shank 14 has at least one thread 11 formed therein, which extends in a helix of constant pitch along the shank, thus forming a main thread 18 having a changing profile contour 20. Along its length, the main thread 18 has a mean thread radius Rg. The mean thread radius is the mean radius of the thread on the main thread 18 and will generally be between the radius of the forming area and the radius of the bearing area; therefore, the mean thread radius Rg will approximate the nominal radius 11. The contour of profile 2-0 is formed by the cross-section through the thread turn in a plane© of section H of the helix in which the central axis M of the screw is located. The radius R of the thread is defined as the distance d©s A t ''V of the screw M to the contour of the profile 20 of the thread turn 16. This will be explained in more detail with reference to figure 3a. 'The scratch: prlndipál 18 has·: a support area T and a formation area E, which gives as highlighted a contour of the formation profile 24 that has a radius of formation area Rf· in the formation area and a contour of the support profile 22 that has a radius of support area fo in the support area T, -18E1 The outline of the formation profile 24 is defined by the projection of the screw turn 16 along the helix over an axially extending area that is three times the length of the mean radius of the screw (3 times R^) from the free end of the stem 2S to a plane in section of the helix H. It will be described in more detail with reference to Figure 3c. This projection therefore corresponds to the projection of 1» “η-'Ι-'T cí a . x0u» hA'bmHe _> n ' ' , ^ti > - - -a . H of the helix in which the central axis M of the screw is located. Figure 2 is a side view of screw 10 and its central axis M. The axial area of ​​screw 10 from the beginning of the thread turn 16 extends over an axial length of 3 times RK, said thread turn then unfolds over the length Ll. In addition, this view shows the section plane H in which the central axis M of the screw enters. The perspective view of the unfolded thread turn 16 is shown in Figure 3a. The unfolded view schematically shows the thread turn 16 of length 11, which corresponds to the length of the unfolded thread turn 16 resulting in an axial extension of 3 times RK. The radius R is shown as a dashed line at various points along the thread turn 16. In this way, the mean radius of the thread is determined along the entire length of the main thread 1S. Figure 3b is the front view of the deployed state, which corresponds to a cross-section of the propeller. Therefore, the projection onto the cross-section results in the outline of the airfoil 24 illustrated in Figure 3c with a maximum extension that represents the outline of the effective airfoil 1'0 of airfoil 24, which will then produce the female thread on the component. The formation area F ends at the FE end of the formation area, i.e., at the position of the main thread IB 15 where the maximum extension of the formation profile contour 24 closest to the footprint still exists in the range of 55% of the mean thread radius in the outward radial direction, before the contour of the subsequent profile in the thread until the end of L1, i.e., the corresponding length of the thread turn 20 with respect to the length 3 times RK in the axial direction, is again within the contour of the formation profile 24. The position of the FE end of the formation area is shown in Figure 4. At point FE, the contour of the formation profile 2d, deriving from the beginning of the thread 25, is present for the last time before the profile contour -20sé fusione can el contour del perfil de apoyo 22 después de una zona de transí.tínn,· .dicho contour· del perfil de.: apoyo 22 se conserva sofero la Longitud restante: del ternilla de la tornillo principal 18 en el presente ejemplo. The contour of the support profile 22 is formed by the projection of the portion of the thread turn 16 onto a plane in section H of the helix, along the length of the helix, over an area that extends axially and begins at an axial distance of 2 / 3 of the mean thread radius from the FE end of the forming area and ends at an axial distance of 5 / 3 of the mean thread radius from the FE end of the forming area. This zone forms at least a partial area of ​​the support area T. Figure 4 is a view illustrating the zone in the unfolded state of the thread 18, which results in maintaining the specified dimensions in the axial direction. Thus, L2 is the length of the thread turn 16 obtained by unfolding the thread. fe- e-' a \vr”,í of the scratch turn. 16 which is obtained by unfolding the axial area of ​​5 / 3 times 20 Ex. The area for determining the contour of the support profile 22 should be 2 / 3 times larger to ensure that the transition area from the formation area F to the support area T is as short as possible. As a result, the transition area -21eu the deployed state is shorter than L2 and is less than or equal to 2 / 3 times Rm in the axial direction. The bearing area T has a length of at least L3 - L2 in the extended state, thus ensuring the essential clamping function of the screw. Figure 5a shows the extended state of the portion of the thread 16 that at least partially forms the bearing area. Figure 5b is a front view of the extended state, and Figure 5b is the corresponding projection of the extended state onto the cross-sectional plane H of the helix that defines the contour of the bearing profile 22. The front view and the projection are identical in this case, since the contour of the profile in the bearing area corresponds in this case to the contour of the bearing profile 9. As seen in figure t, the contour of the support profile 22 and the contour of the formation profile 24 are paired with each other in such a way that in the event of an overlap of the contour of the support profile 22 and the contour of the formation profile 24, at least in zone E which is 2S extends outwards in the radial direction from the 851 of the radius Ry of the formation area, the contour 22 of the support profile will be completely within the contour of the formation profile 24. Figure 7 shows an enlarged view of zone E. While the distance Al between the flanks of the contour of the formation profile 24 and the contour of the support profile 22 -22 can be chosen according to the elasticity of the material, this should preferably be between 6.03 mm and 0.05 mm, in particular 0.04 mm, for a screw with a nominal diameter of 5 Wu Preferably, this u > s:¿n.ua cetn^-xx remaining ah all 5 the flank, at least in the ñ zone. Figure 8a is an enlarged view of zone Ξ of the formation profile contour 24, which delimits a surface of the formation profile 20 that is formed radially inwards, measured at a range of 10% of the radius of the formation area from the maximum orthogonal distance of the formation profile contour to the screw centerline. Figure 3b is an enlarged view of zone E of the bearing profile contour 22, with the bearing profile contour 22 defining a surface 28 of the bearing profile that is measured radially inwards at a range of 10% of the radius RE of the formation area from the maximum orthogonal distance, which corresponds to R, of the bearing profile contour from the screw centerline. According to the invention, the surface of the forming profile 2o is larger than the surface of the support profile 28, which has the advantage that even acute flank angles can be made without excessive stress on the material in which the screw is inserted, thus achieving a large tensile force at a low insertion angle. The alpha angle of flane of the profile contour of S formation 24 is determined as illustrated in the view of figure 9.* This angle corresponds to 180“ minus the sum of the base angles (betel, betas} of a trapezoid formed because the bases of the trapezoid are constituted by the section lines parallel to the axis of the screw at 8% of the radius of the formation profile and at 95% of the radius of the formation profile bs·. The base angles are the angles at the longest base of the trapezoid, that is, at the section line at 85%. The flanging angle is less than 35° and, in particular, 15 is between 20° and 33°. The same rule for determining the flank angle also applies to the contour of the support profile 22, with the section lines fixed at and 95% of the radius of the support profile R?. Figure 10 is a comparative view of the width B of the formation profile contour at 95% of the formation radius and the width R of the support profile contour. In this case, the width B of the formation profile contour 24 is greater than the width S of the support profile contour 22. In the example illustrated in Figure 10, the width of the support profile contour 22 is approximately 10% smaller than the width B of the formation profile contour 24. In this example, the contour of the formation profile 24 and the contour of the support profile 22 are symmetrical. The axis of symmetry is orthogonal to the central axis M of the bolt that cuts the profile contour 22, 24 at half the width B of B, as seen above. Figure 11 is a view of another embodiment of the thread in the bearing area T, in which case the transition from the thread flank to the thread root is flatter than in the view of the figures in the previous drawings. As a result, in the area radially within the ESI of the forming area radius, the contour of the bearing profile 22 is at least partially outside the contour of the forming area 24. Figure 12 is a view of another embodiment of a screw according to the invention, the shank of which additionally has a drill rod 30 at the free end of the screw shank. The drill rod comprises at least two turns of drill thread 32, 34 with a radius that reaches at most 90% of the radius of the formation area and which form a drill zone AB in which the turns of -25 drill thread 32, 34 have the same radius path on the associated helix and in which, in addition, the thread radius of the main thread is less than or equal to the thread radius of the drill thread turns at the same axial distance from the 5 free end 2S of the screw. In this embodiment, the 15th thread turn of the main thread 18 in the drill shank has the same radius R as the drill shank 30, at the same axial distance 10 from the free end of the screw. The drill thread turns 32 and 34 begin directly at the free end 25 of the screw shank in the core. This ensures that the screw will be ideally guided from the moment it is positioned for drilling. In this embodiment, the drill shank 30 extends over approximately one turn, with the drilling zone ending at approximately one-third of a turn. In this embodiment, the diameter of the free end of the stem of the screw corresponds at least to that of the bend radius of the forming area Rr. The drilling zone will now be described in more detail with reference to Figures 13a and 13d. Figure 13a is an enlarged side view of the free end of the screw shank with three transverse lines. The first transverse line pp is located in the center of the drilled zone AS. The transverse line QQ is located at the end of the drilled zone AL, and the transverse line SS is located above the drilled zone. Figure 13b is a cross-sectional view taken along the transverse line FP. As can be seen clearly in Figure 13b, the threads in the drilled zone, i.e., the two turns of 10 drilled threads 32, 34 and the thread turn 16, have the same thread radius. The same is true for the end of the drilled zone as seen in Figure 13c, in which threads 16, 32, and 34 also have the same thread radius R at the same axial distance from the free end of the screw shaft. Finally, Figure 13d is a cross-sectional view taken along the transverse line SS and clearly illustrates the thread radii of the two drill turns 32, 34 and the thread turn 1δ of the main thread 20' outside the drilling zone. In this region, the thread radii R of drill turns 32, 34 are significantly smaller than the thread radius of thread turn 16 of the main thread 18 on this transverse line. In this embodiment, the drill rods emerge smoothly after the drilling zone, while the The 27th turn of the main thread continues to increase until it reaches the contour of the .formation profile. Figure 14 is a cross-sectional view illustrating the ratio of a screw connection 40. The screw connection 40 comprises a screw 42 and a plastic component 46 with a pilot hole 44 made therein. The front forming area F of the screw 42 is used to preform a thread turn in the plastic component 46, which thread turn then engages with the rear bearing area T of the thread turn. Figure 15a is an enlarged view of detail 1 illustrating the thread engagement in the forming area F and detail 2 illustrating the thread engagement in the bearing area of ​​the main thread. The outline of the forming profile 50 is shown in Figure 15a. The subsequent thread with the outline of the support profile 58 in the screw bearing area is shown in the enlarged detail view of Figure 15b. The detail view of Figure 15b shows the thread turn in the hebibra rosette in its spring-rebound state with the outline line 56. Despite the spring-rebound of the thread, the 25 flanks of the thread of the support profile outline 58 are -28 still sear a distance A2 from the elastic female thread. This allows the thread of the support profile contour to screw into the female thread almost without friction. Only the final tightening of screw 42 will cause the thread in the support area to press against the flank of the female thread, thus creating a frictional connection in the direction of rotation. By making the surface area of ​​the tip of the support profile contour 58 smaller than the surface area of ​​the forming profile contour 50, both a low insertion torque and high pull-out strength can be guaranteed, as this prevents structural damage to the plastic material, while still ensuring sufficient spacing of the thread flanks between the elastic female thread and the thread in the support area.

Claims

CLAIMS 1. A screw (10) having a central axis (M) comprising a footprint (12) and a threaded stem (14) having a thread turn (11) which at least in parts extends along the stem in a helix of constant pitch and which forms a main thread (11) having: a mean thread radius (θα) along its length, the thread radius (R) being the maximum orthogonal distance from the axis (M) of the screw to the contour (10) of the thread profile (20), the main thread having a forming profile contour (24) of a forming area radius (Rr) obtained in the forming area (F) and a bearing profile contour (22) of a bearing area radius (Rr) -what: is obtained in the support zone· (2) , whose contour of the formation profile (24) is defined by the projection of the thread turn along.the helix over a zone that extends axially from a length three times the mean thread radius:: (W) domehtundó ·ό©όό© the free end (2Si of the váetagd 20 to the section plane (H) of the helix, terminating said formation area (F) at the point of the helix at which the contour of the formation profile (24} nearest to the footprint extends 'ai.símente outwards in a range of 85% of the mean thread radius before the contour of the subsequent profile (20) 25 is located again within the cbntprno of the formation profile ~ 30 ~ (24), being dcítn.-said contour of the support profile (22) by the projection of the thread turn along the helix on a plane in section (H) of the helix in a zone that coincides with a dancer ué 2 / z times the mean radius of that thread from the end of the formation area (FE) and ends at 5 / 3 times the mean radius of the thread (¾) , and in the case of an overlap of the contour of the support profile (22) and the contour of the formation profile (24), at least in the zone that extends radially outwards from 85% of the radius of the formation area ( ¾) f the contour of the support profile (22) will be completely.· within the contour of the tcmia'ún profile (24) characterized in that a surface of the forming profile (26) that is delimited by the contour of the forming profile (24), measured in a range of 10% of the radius of the forming area (¾) from the maximum orthogonal distance of the contour of the forming profile (24) from the central axis of the screw radially inwards, is greater than a surface of the support profile (28) that is delimited by the contour of the support profile (22), measured in a range of 10% of the radius of the forming area (¾) from the maximum orthogonal distance of the contour of the support profile (22) from the central axis of the screw radially inwards.

2. Screw according to claim 1, characterized in that the contour of the forming profile (24) and the contour of the bearing profile (22) have a flank angle (α) less than 35.

3. Screw according to claim 1 or 2, characterized in that the radius of the bearing area (¾) is smaller by between 1% and 3% than the radius of the forming area (Φ).

4. Screw according to any of claims 1 to 3, characterized in that the contour of the bearing profile (22) has a width (Φ) at 95% of the radius of the bearing area (¾) or Φ < Φ < 1 Φ).

5. Screw according to claim 4, characterized in that...The width (¾) of the contour of the support profile (22) is at least 10%, in particular at least 20%, less than the width (Bd) of the contour of the forming profile (24), 20 6, Screw according to any of the preceding claims, characterized in that the contour of the forming profile (24) and / or the contour of the support profile (22) are symmetrical. ~32.

7. Screw according to any of the preceding claims, characterized in that the contour of the forming profile (24) does not increase beyond a length of less than twice the pitch.

8. Screw according to any of the preceding claims, characterized in that the ratio between the core diameter and twice the mean thread radius (¾) is between 0.6 and 0.8, 1Q 9. Screw according to any of the preceding claims, characterized in that in the region extending radially within the radius of the forming area (T), the contour of the bearing profile (22) is at least partially outside the contour of the forming profile (24).

10. Screw according to any of the preceding claims, characterized in that the core diameter in the forming area is less than or equal to the core diameter in the bearing area (T).

11. Screw according to any of the preceding claims, characterized in that the shank has a drill rod (30) in the free-running area (25) of the screw shank, said drill rod (30) comprising at least two turns of drill thread (32, 34) having a radius at most 90% of the radius (R) of the region.formation zone and forming a drilling zone (AB) in which the drilling thread turns (32, 34) have the same radius path and, furthermore, in the drilling zone (AB) the thread radius of the main scraper (18) is less than or equal to the thread radius of the drilling thread turns {32, 34}. 12< Screw according to claim 11, 10 characterized in that the main thread {18} in the drilling frog, (AB.) has: the same radius of scraper (R) as the channel by formation (32, 34}.

13. Screw according to claim 11, 15 characterized in that at least three drill thread turns (32, 34) are provided, the thread radius (R) of the main thread (18) in the drill hole (AB) being less than that of the drill hole, 20 14. Screw according to any of claims 11 to 13, characterized in that the drill thread turns (32, 34) begin at the core, with their thread radius (R) increasing continuously in the direction of the drill area: (T i. * -34 — 15. Screw according to any of claims 11 to 14, characterized in that the thread turns (15, 32, 34) of the same thread radius tS are uniformly distributed circumferentially in the drilling zone (AB).

15. Screw according to any of claims 11 to 15, characterized in that the diameter of the free end core of the screw is at least 25%, at least 30%, at least 40%, at least 50%, at least 60% of twice the radius of the forming area.

17. Thyme.· according to any of claims 11 to 15, characterized in that the rose-shaped turns (16, 32, 34) in the perforation zone (AB) have their beginning at the same 15 p 1 transverse 1.

18. Screw according to any one of claims 11 to 17, characterized in that the thread turns (16, 32, 34) in the drilling zone (AB) have the same profile contour.

20. Screw according to any one of claims 11 to 18, characterized in that the drill shank (30) directly abuts the free end of the shank (25).

20. Screw according to any one of claims 11 to 19, characterized in that the drill shank (30) begins at a distance from the free end of the shank 12.

50. 2.

1. Screw according to any one of claims 11 to 20, characterized in that the drill shank (30) and the main thread (13) are rolled threads. Screw according to any one of claims 11 to 21, characterized in that the threads in the drilled section (30) have a more obtuse flank angle than the main thread (18) outside the drilled section (AB).Screw according to any one of claims 11 to 22, characterized in that the drill shank (30) terminates abruptly. 2rf Screw according to any one of claims 11 to 23, characterized in that the drill shank (30) extends over a maximum of two turns. 25* Method for producing a screw connection, comprising a screw (10, 12) according to any one of claims 1 to 24, characterized in that the * Λ * -36- m.ru.l'c fo; -í1 un.ll·- >„ j) .ui, ;r- l· iuk ufo in a component (4 6) of plastic material, thus forming a counter thread in the plastic with the contour of the deformation profile (50) in the formation area (F), after which the counter thread in the support area returns to its position to prevent it from coming into contact with the thread in the support area (T) during the screw insertion process, and to ensure that the thread in the support area (T) is only pressed against the counter thread when the screw is finally tightened into the component.

21. Method according to claim 25, characterized in that the radius of the pilot hole is 80% of the radius of the forming area.

27. Threaded connection (40) comprising a screw (42) and a component (46) of plastic material, the scratched connection being made using: the method of claim 25 and / or that of claim 26.

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