CONNECTING ELEMENT HAVING A THREADED CONNECTING PART

Abstract

A connecting element (1, 11) has a connecting part (2, 12) which has a thread (3, 13), wherein the thread (3-13) comprises a nominal diameter (d), a flank diameter (d.sub.2), a pitch (S.sub.ges), and —thread turns (n.sub.ges), wherein the pitch (S.sub.ges) of the thread (3, 13) is made up of a first pitch (S.sub.norm) and of a second pitch (S.sub.diff), wherein the first pitch is a standard pitch (S.sub.norm), in particular corresponding to the nominal diameter (d), and wherein the second pitch (S.sub.diff) corresponds to an amount of elastic and/or plastic extension under strain (f, fz) of the threaded connecting part (2, 12), wherein the extension under strain (f, fz) occurs in a predetermined operating state of the threaded connecting element (1, 11).

Claims

1. A connecting element having a connecting part, which has a thread, wherein the thread has a nominal diameter, a flank diameter, a pitch, and a number of thread turns, wherein the pitch of the thread is made up of a first pitch and a second pitch, wherein the first pitch is a standard pitch corresponding to the nominal diameter, and wherein the second pitch corresponds to an amount of elastic or plastic extension under strain of the threaded connecting part, wherein the extension under strain occurs in a predetermined operating state of the threaded connecting element.

2. The connecting element according to claim 1, wherein the elastic or plastic extension under strain runs in the direction of extension of the thread due to the action of the axially extending, acting force, wherein in the predetermined operating state the threaded connecting part is designed for an acting force, wherein the acting force comprises an operating force, which acts on the connecting element as an external tensile or compressive force, wherein the acting force comprises an assembly pretensioning force, with which the connecting element rests against a component in a fastening manner via an intermediate part, wherein the second pitch is less than or greater than the first pitch of the thread, wherein the first pitch corresponds to the nominal diameter according to a metric standard or an inch standard.

3. The connecting element according to claim 1, wherein the second pitch has a quotient having a dividend and a divisor, wherein the dividend comprises the elastic or plastic extension under strain of the threaded connecting part at the force acting in the operating state and the divisor comprises the number of thread turns screwed in during the operating state, wherein the second pitch is variable by a factor in a range between 100% and 550%, wherein at a factor of 100%, all thread turns screwed in during the operating state transmit forces, wherein at a factor of 550%, at least a three thread turns furthest from the start of the thread during the operating state transmit forces.

4. The connecting element according to claim 1, wherein the second pitch comprises a product composed of a displacement of the thread core and the force acting in the operating state, wherein the displacement of the thread core comprises a quotient having a dividend and a divisor, wherein the dividend comprises the length of the threaded part screwed in during the operating state, with which the connecting part is screwed in a mating thread, wherein the divisor comprises a product of the elastic modulus of the material of the connecting element and the cross-section of the thread, wherein the cross-section of the thread corresponds to the core cross-section for an external thread or to the nominal cross-section for an internal thread.

5. The connecting element according to claim 1, wherein a distance between two tooth flanks of two adjacent teeth of the thread along the flank diameter or a distance between two tooth flanks of a thread tooth of the thread along the flank diameter is varied by an amount, wherein the distance corresponds to the corresponding distance resulting from the first pitch, wherein preferably the distance changed by an amount along the flank diameter, wherein the amount corresponds to a product of the second pitch and a sum of the number of thread turns and 1, wherein the number of thread turns is the number of thread turns screwed in during the operating state, wherein the tooth flank angle of the thread remains unchanged and in particular corresponds to the tooth flank angle of the first pitch.

6. The connecting element according to claim 1, wherein the second pitch comprises an elastic or plastic extension under strain of the tooth flanks of the threaded part screwed in during the operating state, on which the force acting in the operating state acts, so that the screwed-in threaded part has a changed length, in particular an increased or shortened length, compared to the unloaded state, wherein the second pitch has a quotient comprising a dividend and a divisor, wherein the dividend comprises the elastic or plastic extension under strain of the tooth flanks of the threaded part screwed in during the operating state when a force is acting on the connecting part, wherein the divisor comprises the number of thread turns screwed in during the operating state.

7. A screw connection for the connection of components, comprising: a first connecting element according to claim 1, and a second connecting element according to claim 1, wherein the first connecting element comprises a first thread and the second connecting element comprises a second thread, wherein the first thread and the second thread are engaged.

8. The screw connection according to claim 13, wherein, for the internal thread, the first pitch is increased by a proportion of the second pitch and, for the external thread, the first pitch is decreased by a proportion of the second pitch, and wherein the proportions of the second pitch of the internal and external threads together result in the second pitch.

9. A method for producing a thread of a connecting part of a connecting element comprising: determining an acting force on a connecting element for connecting components in an operating state, selecting a thread with a nominal diameter corresponding to the acting force, determining the pitch of the thread, wherein the pitch of the thread is made up of a first pitch and a second pitch, wherein the first pitch is a standard pitch corresponding to the nominal diameter, and wherein the second pitch corresponds to an amount of elastic or plastic extension under strain of the threaded connecting part occurring in the predetermined operating state of the connecting element, and producing the thread.

10. The method according to claim 9, wherein the second pitch is less than or greater than the first pitch of the thread, wherein the acting force comprises an operating force, which acts on the connecting element as an external tensile or compressive force, wherein the acting force comprises an assembly pretensioning force, with which the connecting element rests against a component in a fastening manner via an intermediate part.

11. The connecting element according to claim 2, wherein the connecting element with the connecting part having a thread is a component with an external thread.

12. The connecting element according to claim 2, wherein the connecting element connecting part with the connecting part having a thread is a component with an internal thread.

13. The screw connection of claim 7, wherein the first thread is formed as an internal thread and the second thread is formed as an external thread.

14. The screw connection of claim 7, wherein the first thread is formed as an external thread and the second thread is formed as an internal thread.

15. The screw connection according to claim 14, wherein, for the internal thread, the first pitch is increased by a proportion of the second pitch and, for the external thread, the first pitch is decreased by a proportion of the second pitch, and wherein the proportions of the second pitch of the internal and external threads together result in the second pitch.

16. The method of claim 10 wherein the production of the thread comprises a non-cutting process.

17. The method of claim 10 wherein the production of the thread comprises a machining process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0176] The connection method is explained in more detail below with reference to examples of embodiments in conjunction with associated drawings. The figures schematically show the following:

[0177] FIG. 1 shows a sectional view of a screw connection for connecting components;

[0178] FIG. 2 shows an enlarged sectional view of the screw connection from FIG. 1;

[0179] FIG. 3 shows an enlarged view from FIG. 2;

[0180] FIG. 4 shows a diagram of an FEM analysis of a screw in a modified internal thread;

[0181] FIG. 5 shows an enlarged view from FIG. 4;

[0182] FIG. 6 shows a view similar to FIG. 5, but for a screw in a standard internal thread;

[0183] FIG. 7 shows a sectional view, similar to FIG. 1;

[0184] FIG. 8 shows a diagram for the strain progression along the thread turns; and

[0185] FIG. 9 shows a diagram of the stress curve along the thread turns.

DETAILED DESCRIPTION

[0186] In the description below, the same reference signs will be used for the same components.

[0187] FIG. 1 shows a sectional view of a screw connection for connecting components.

[0188] More precisely, FIG. 1 shows a screw connection with a first connecting element 1 and a second connecting element 11.

[0189] Here, the first connecting element 1 has a first thread 3 and the second connecting element 11 has a second thread 13, wherein at least a portion of the first thread 3 and all of the second thread 13 are engaged.

[0190] The first thread 3 is designed as an external thread and the second thread 13 is designed as an internal thread, wherein the connecting element 1 is designed as a screw and the connecting element 11 is designed as a wheel flange.

[0191] In the present case, the internal thread has a first pitch S.sub.norm, which corresponds to the standard pitch for this thread, increased by a second pitch S.sub.diff.

[0192] FIG. 2 shows an enlarged sectional view of the screw connection from FIG. 1.

[0193] The connecting element 11 with internal thread is described in more detail below, although the statements made there are also applicable to, for example, a screw with an external thread.

[0194] According to FIG. 1, the connecting element 11 has a connecting part 12, which has a thread 13.

[0195] The thread 13 has a nominal diameter d, a flank diameter d.sub.2, a pitch S.sub.ges, and thread turns n.sub.ges.

[0196] The pitch S.sub.ges of the thread 13 is made up of a first pitch S.sub.norm and a second pitch S.sub.diff, wherein the first pitch is a standard pitch S.sub.norm, in particular corresponding to the nominal diameter d.

[0197] In other words, this means:

[00022]$S_{ges}=S_{\mathrm{norm}}+S_{\mathrm{diff}}$

[0198] The second pitch S.sub.diff, on the other hand, corresponds to an amount of elastic and/or plastic extension under strain f, f.sub.Z of the threaded connecting part 12, wherein the extension under strain f, f.sub.z occurs in a predetermined operating state of the threaded connecting element 11.

[0199] In this predetermined operating state, the threaded connecting part 12 is designed for an acting force F.

[0200] The acting force F comprises an operating force F.sub.B, which acts on the connecting element 11 as an externally acting tensile and/or compressive force, and an assembly pretensioning force F.sub.M, with which the connecting element 11 is fastened to a component or to the connecting element 1 via an intermediate part 14 (F=F.sub.B+F.sub.M).

[0201] Due to the action of the axially extending, acting force F, the elastic and/or plastic extension under strain f, f.sub.Z runs in the direction of extension of the thread 13.

[0202] As mentioned above, the second pitch S.sub.diff increases the first pitch S.sub.norm of the thread 13, wherein the first pitch S.sub.norm has a metric standard, in particular a metric thread, corresponding to the nominal diameter d.

[0203] To be precise, the second pitch S.sub.diff has a quotient that has a dividend and a divisor.

[0204] The dividend comprises the elastic and/or plastic extension under strain f of the threaded connecting part 12 at the force F acting in the operating state, and the divisor comprises all the thread turns n.sub.ges of the thread 13 that are screwed in during the operating state.

[0205] This is expressed in an equation as follows:

[00023]$S_{\mathrm{diff}}=f\left(F\right)/n_{ges}$

[0206] Furthermore, the elastic and/or plastic extension under strain f comprises a product composed of the displacement δ of the thread core and the force F acting in the operating state (f=δ*F).

[0207] Furthermore, the displacement δ of the thread core has a quotient that has a dividend and a divisor.

[0208] The dividend comprises the length l.sub.e of the threaded part screwed in during the operating state, with which the connecting part 12 is screwed in a mating thread 3.

[0209] The divisor comprises a product of the elastic modulus E of the material of the connecting element 12 and the cross-section of the thread 13, wherein the cross-section of the thread 13 corresponds to the nominal cross-section A.sub.N for an internal thread.

[0210] These statements can be expressed in an equation as follows:

[00024]$\delta =l_e/\left(E*A_N\right)$

[0211] In order to now have all thread flanks of the connecting part 12 rest against the connecting part 2 of the connecting element 1, the second pitch S.sub.diff can be varied with a factor P in a range between 100% and 550% or between 1 and 5.5, wherein in the present case with the factor P of 100% all thread turns n.sub.ges screwed in during the operating state transmit forces.

[0212] If the factor P were equal to 550%, at least the three thread turns farthest from the thread start in the operating state would transmit forces.

[0213] The above statements offset with numbers lead, for example, to the following interpretation of the pitch S.sub.ges.

[00025]$S_{ges}=S_{\mathrm{norm}}+S_{\mathrm{diff}}{S}_{\mathrm{diff}}=f\left(F\right)/n_{ges}=\delta *F/n_{ges}=l_e/\left(E*A_N\right)*F/n_{ges}$

[0214] Preferably, the number of all thread turns n.sub.ges of the thread is reduced by a factor of 1 in case of an internal thread. This means, preferably:

[00026]$n_{\mathrm{ges},\mathrm{internal}\mathrm{thread}}=n_{\mathrm{ges}}-1\mathrm{or}{n}_{\mathrm{teil},\mathrm{internal}\mathrm{thread}}=n_{\mathrm{teil}}-1$

[0215] With this improvement, an even better stress distribution can be achieved. For simplicity and clarity, this preferred improvement is omitted below.

[0216] Thus, if a displacement of the core diameter of 2 μm per millimeter is expected for a standard pitch S.sub.norm of 1.5 mm for an M8 thread and a screw-in length l.sub.e of 10 mm, the pitch difference S.sub.diff should preferably be designed as follows:

[0217] Displacement δ of the core diameter of an M8 thread (taken from table) after standard tightening to 10 mm screw-in length l.sub.e for example:

[00027]$$\begin{gathered} 2\mathrm{.Math.m}/\mathrm{mm}*10=20\mathrm{.Math.m} \\ \mathrm{Number}\mathrm{of}\mathrm{thread}\mathrm{turns}\left(n_{ges}\right)\mathrm{in}\mathrm{engagement}:10\mathrm{mm}/1.5\mathrm{mm}=6.66666 \\ \mathrm{Pitch}\mathrm{difference}{S}_{\mathrm{diff}}\text{:}\left(20\mathrm{.Math.m}/6.66666\right)*1=3\mathrm{.Math.m} \end{gathered}$$

[0218] To enable thread partners with different pitches to be screwed in, it is also preferable to increase the clearance x between the teeth in the internal thread and/or in the external thread or the distance x between two tooth flanks of two adjacent teeth of the thread.

[0219] The amount z by which the clearance x or the distance x is increased should be in the range of z=S.sub.diff*(n+1).

[0220] Optimum tooth space x or distance x between two tooth flanks of two adjacent teeth of the thread by about 3 μm×7.66666=23 μm larger than the tooth.

[0221] FIG. 3 shows an enlarged view from FIG. 2, wherein the following explanations apply to FIGS. 2 and 3.

[0222] In addition to the changed pitch S.sub.ges (S.sub.ges=S.sub.norm+S.sub.diff), the connecting element 11 has a distance x between two tooth flanks of two adjacent teeth of the thread 13 along the flank diameter d.sub.2, which is changed by an amount z.

[0223] Here, the distance x corresponds to the corresponding distance resulting from the first pitch S.sub.norm.

[0224] In the present example, the distance x between the two opposing tooth flanks of two adjacent teeth is increased along the flank diameter d.sub.2 by the amount z, wherein the amount z corresponds to the product of the second pitch S.sub.diff and the sum of the thread turns n.sub.ges of the thread screwed in during the operating state or their number and 1. As already indicated above, this is expressed in an equation as follows:

[00028]$z=S_{\mathrm{diff}}*\left(n_{ges}+1\right)$

[0225] This makes it easy to screw the threaded connecting part 12 into a mating thread 3 or into a connecting part 2 having a mating thread. Also, with this embodiment, it can be ensured that the thread turns furthest from the start of the thread transmit forces and not the thread turns located at the start of the thread 12, as is usual with a standard thread.

[0226] In other words, each distance x between two opposing tooth flanks of two adjacent teeth is increased along the flank diameter d.sub.2 by the amount z, thus increasing the clearance x or distance x between the teeth or thread teeth.

[0227] From a different perspective, the width y of each tooth of the thread 13 or the distance y between two tooth flanks of a thread tooth of the thread 13 is changed by an amount z along the flank diameter d.sub.2.

[0228] Here, the distance y corresponds to the corresponding distance resulting from the first pitch S.sub.norm.

[0229] To be precise, the distance y between two tooth flanks of a thread tooth of the thread 13 along the flank diameter d.sub.2 is decreased by an amount z which corresponds to the product of the second pitch S.sub.diff and the sum of the thread turns n.sub.ges, n.sub.teil of the thread screwed in during the operating state or their number and 1.

[0230] As a result, the distance y is expressed in an equation as follows:

[00029]$y=S_{\mathrm{diff}}*\left(n_{ges}+1\right)$

[0231] Regardless of whether the distance x or the distance y is considered, the tooth flank angle of the thread 13 remains unchanged and corresponds to the tooth flank angle of the first pitch S.sub.norm.

[0232] Furthermore, the second pitch S.sub.diff comprises an elastic and/or plastic extension under strain or compression f.sub.Z of the tooth flanks of the threaded part 13 screwed in during the operating state, on which the force F acting in the operating state acts. Thus, the screwed-in threaded part 13 has a changed length compared to the unloaded state, in particular an increased length under a tensile load. In other words, the threaded connecting part of the connecting element also elongates due to the deformation of the threaded teeth or their tooth flanks or the connecting part does not elongate due to the extension under strain of the tooth flanks, because the tooth flanks compensate for the extension by deformation.

[0233] Here, the second pitch S.sub.diff corresponds to a quotient that has a dividend and a divisor

[0234] The dividend comprises the elastic and/or plastic extension under strain or compression f.sub.Z of the tooth flanks of the threaded part screwed in during the operating state when a force F is acting on the connecting part 12.

[0235] The divisor has all the thread turns n.sub.ges of the thread 13, which are the number of thread turns screwed in during the operating state.

[0236] This is preferably expressed in an equation as follows:

[00030]$S_{\mathrm{diff}}=f_Z\left(F\right)/n_{ges}$

[0237] In a screw connection, as shown in FIG. 1, both partners deform in the operating state; namely the first connecting element 1 and the second connecting element 11, which is screwed to the first connecting element 1.

[0238] Accordingly, it is advantageous if the second pitch (S.sub.diff) is formed from the sum of the extension under strain f.sub.first connecting element of the first connecting element 1 or its connecting part 2 and the extension under strain f.sub.second connecting element of the second connecting element 11 or its connecting part 12.

[0239] This is expressed in an equation as follows:

[00031]$S_{\mathrm{diff}}=f_{\mathrm{first}\mathrm{connecting}\mathrm{element}}+f_{\mathrm{second}\mathrm{connecting}\mathrm{element}}$

[0240] In light of the explanations concerning the connecting element 11 above, which are applicable here to the first connecting element 1, the following equations and the explanations made therewith under the first aspect may also be used.

[00032]$S_{\mathrm{diff}}=f\left(F\right)/n_{ges}\mathrm{or}{S}_{\mathrm{diff}}=f\left(F\right)/n_{\mathrm{teil}}$$f=\delta *F$$\delta =l_e/\left(E*A_3\right)\mathrm{for}\mathrm{an}\mathrm{external}\mathrm{thread}\mathrm{or}$$\delta =l_e/\left(E*A_N\right)\mathrm{for}\mathrm{an}\mathrm{internal}\mathrm{thread}$

[0241] For a screw connection with one internal and one external thread, the second pitch (S.sub.diff) is preferably determined as follows:

[00033]$S_{\mathrm{diff}}=\left[l_e/\left(E*A_3\right)*F+l_e/\left(E*A_N\right)*F\right]/n_{ges}$

[0242] Since the first and second connecting elements 1, 11 are screwed together over the same length l.sub.e and thus have the same number of thread turns engaged with each other, n.sub.ges is therefore equal to n.sub.teil or n.sub.ges=n.sub.teil.

[0243] Advantageously, the second pitch S.sub.diff is variable by a factor P in a range between 100% and 550% or between 1 and 5.5, as shown above. This is expressed in an equation as follows:

S.sub.diff*P; where P is variable between 1(100%) and 5.5(550%).

[0244] In summary, the pitch S.sub.ges of the thread is advantageously made up of the first pitch S.sub.norm and the second pitch S.sub.diff with the factor P. This is preferably expressed in an equation as follows:

[00034]$S_{ges}=S_{\mathrm{norm}}+P*S_{\mathrm{diff}}$

[0245] Furthermore, the second pitch S.sub.diff comprises an elastic and/or plastic extension under strain or compression f.sub.Z of the tooth flanks of the threaded part 3, 13 screwed in during the operating state, on which the force F acting in the operating state acts, so that the screwed-in threaded part has a changed length, in particular an increased or shortened length, compared to the unloaded state.

[0246] In other words, the connecting part 2, 12 having a thread 3, 13 of the connecting element 1, 11 also elongates due to the deformation of the threaded teeth or their tooth flanks.

[0247] If the first and second threads 3, 13 are now engaged, as in FIGS. 1 and 2, both threads and their tooth flanks deform in the operating state and thus under the action of an assembly pretensioning force and an operating force.

[0248] The extension under strain of the threaded connecting parts 2, 12 and the compression of the tooth flanks, such as under tensile load on the connecting elements 1, 11, consequently elongate the connecting parts 2, 12 of the two threads 3, 13.

[0249] This means that the second pitch S.sub.diff changes by the sum of the compression or extension under strain f.sub.Z, first connecting element of the first thread and the compression or extension under strain f.sub.Z, second thread of the second thread.

[0250] This is preferably expressed in an equation as follows:

[00035]$S_{\mathrm{diff}}=\left[l_e/\left(E*A_3\right)*F+l_e/\left(E*A_N\right)*F\right]/n_{\mathrm{ges}}+f_{Z,\mathrm{first}\mathrm{connecting}\mathrm{element}}+f_{Z,\mathrm{second}\mathrm{connecting}\mathrm{element}}$

[0251] A method for producing the thread 13 of the connecting part 12 of the connecting element 11 comprises the following steps:

[0252] Determining an acting force F on the connecting element 11 for connecting components in an operating state,

[0253] selecting a thread 13 with a nominal diameter d corresponding to the acting force F,

[0254] Determining the pitch S.sub.ges of the thread 13, wherein the pitch S.sub.ges of the thread 3, 13 is made up of a first pitch S.sub.norm and a second pitch S.sub.diff.

[0255] Here, the first pitch is a standard pitch S.sub.norm, in particular corresponding to the nominal diameter d, and the second pitch S.sub.diff is an elastic and/or plastic extension under strain f, f.sub.Z of the threaded connecting part 12 occurring in the predetermined operating state of the connecting element 11.

[0256] Finally, the thread 13 is produced.

[0257] Production is possible by means of a non-cutting process, in particular a cold extrusion process or a hot extrusion process, preferably forging on a forging press.

[0258] It is also possible that the production of the thread 13 comprises a machining process, in particular screw turning, screw milling, screw grinding or thread whirling.

[0259] To illustrate the effects of the changes to the thread 13, the following figures show the following:

[0260] FIG. 4 shows a diagram of an FEM analysis of a screw in an internal thread modified, as previously described;

[0261] FIG. 5 shows an enlarged view from FIG. 4;

[0262] FIG. 6 shows a view similar to FIG. 5, but for a screw in a standard internal thread;

[0263] FIG. 7 shows a sectional view, similar to FIG. 1;

[0264] FIG. 8 shows a diagram of the strain progression along the thread turns; and

[0265] FIG. 9 shows a diagram of the stress curve along the thread turns.

[0266] FIG. 5 shows that the external thread of screw 3 is subjected to stresses uniformly along the length of the screw due to the modified internal thread (not shown).

[0267] Here, the arrows below the screw illustrate the stress occurring at the corresponding location.

[0268] The arrows above the screw, on the other hand, illustrate the contact stress or surface pressure between the thread teeth of the internal thread (not shown) and the external thread of the screw.

[0269] In comparison, FIG. 6 shows the loads on an external thread of a screw that is screwed into an internal standard thread.

[0270] It is immediately apparent from the arrows below the screw that the loads or stresses that occur are greatest in the first thread turns and then decrease significantly thereafter.

[0271] The arrows above the screw, on the other hand, illustrate the contact stress or surface pressure between the thread teeth of the internal thread (not shown) and the external thread of the screw.

[0272] The aforementioned stresses or loads shown in FIG. 6 cause the screws to tear off at the first thread turns.

[0273] In contrast, as mentioned, the screw according to FIG. 5 is stressed or loaded much more uniformly starting from the depth or at the thread turns furthest away from the start of the thread and over the length l.sub.e of the threaded part screwed in during the operating state, with which the connecting part is screwed into the internal thread.

[0274] Whereas in the screw shown in FIG. 6 the frontmost thread turns at the start of the thread (on the left in FIGS. 4 to 6) are subjected to the greatest contact stress to the internal thread (not shown), the situation is different in the connecting element, as shown in FIG. 5.

[0275] Here, the thread turns furthest away from the start of the thread (on the right in FIGS. 4 to 6) are stressed with the greatest contact stress to the internal thread (not shown), resulting in a distribution of the occurring stresses to several thread turns of a screw connection starting from the depth or starting at the thread turns furthest away from the start of the thread. The front thread turns are only loaded with the tensile stress but not with the contact stress or surface pressure of the respective tooth flank.

[0276] FIGS. 7 to 9 show the above statements clearly in the form of a diagram.

[0277] While FIG. 7 again shows the screw connection from FIG. 1 with the first and tenth thread turns of the external thread of the connecting element 11, FIGS. 8 and 9 show the strains and stresses in the thread turns of the screw.

[0278] It is again emphasized that the screw or its thread has an unchanged pitch or a standard pitch.

[0279] On the other hand, the internal thread of the connecting element 11 is modified.

[0280] Since the screw is screwed into the internal thread, the following statements regarding the external thread of the screw or the screw apply analogously to the internal thread, which deforms identically to the screw, since they are in engagement with one another.

[0281] Thus, in FIG. 8, for each individual thread turn and for two different loads (60 kN and 80 kN), the elastic and/or plastic extension under strain of the screw manufactured according to a standard and screwed into a modified internal thread is shown.

[0282] FIG. 8 shows that the version V1, which is a standard screw in a modified internal thread, stretches more uniformly along the thread turns than a standard screw in a standard internal thread (V2).

[0283] FIG. 9 shows, for each thread turn and for two different loads (60 kN and 80 kN), the stress of the screw produced according to a standard and screwed into a modified internal thread.

[0284] FIG. 9 shows that version V2, which is a standard screw in a standardized internal thread, is unevenly loaded along the thread turns. On the other hand, the standard screw in the modified internal thread is more evenly loaded with stresses along the thread turns (V1).

LIST OF REFERENCE SYMBOLS

[0285] 1 Connecting element [0286] 2 Connecting part [0287] 3 Thread [0288] 11 Connecting element [0289] 12 Connecting part [0290] 13 Thread [0291] 14 Intermediate part [0292] d Nominal diameter [0293] d.sub.2 Flank diameter [0294] A.sub.3 Core cross-section [0295] A.sub.N Nominal cross-section [0296] S.sub.ges Pitch [0297] S.sub.norm First pitch [0298] S.sub.diff Second pitch [0299] n.sub.ges Thread turns [0300] n.sub.teil Thread turns [0301] f, f.sub.Z Extension under strain [0302] F Force [0303] F.sub.M Assembly pretensioning force [0304] F.sub.B Operating force [0305] P Factor [0306] δ Displacement [0307] E Elastic modulus [0308] x Distance between two tooth flanks of two adjacent teeth of the thread along the flank diameter [0309] y Distance between two tooth flanks of a thread tooth of the thread along the flank diameter [0310] z Amount by which the distance x or y is changed [0311] l.sub.e Screw-in length or length of the threaded part screwed in during the operating state, with which the connecting part is screwed in a mating thread