Screw for screwing into plastic

A screw (10) having a screw center axis (M), comprising:

• a drive (12) and a threaded shank (14);
• said threaded shank (14) has a thread turn (16) which partially extends along said shank in a helix of constant pitch and which forms a main thread (18) that has a thread radius (R) and a mean thread radius (RM) over its length;
• said threaded shank (14) being insertable in a plastic component (46);
• said thread radius (R) being the maximum orthogonal distance from said screw axis (M) to a profile contour of said thread turn;
• said main thread (18) has a bearing area (T), a transitional area, and a forming area (F);
• a forming profile contour (24) having a forming area radius (RF);
• a bearing profile contour (22) having a bearing area radius (RT);
• said forming area radius (RF) is greater than said bearing area radius (RT);
• said forming area (F) terminating at an end point defining a forming area end (FE) of said shank;
• said main thread (18) comprises said forming profile contour (24) in said forming area (F);
• said forming area extends over an axial length three times the said mean thread radius (RM) starting from a free end (25) of said shank to said forming area end (FE), said forming area comprising said forming profile contour at said forming area end;
• said main thread (18) comprises said bearing area and said bearing profile contour (22) that extends axially over a length of said threaded shank starting at a distance of ⅔ times said mean thread radius (RM) from said forming area end (FE);
• said main thread (18) in said transitional area beginning at said forming area end (FE) of said shank and continuing a maximum length of ⅔ RM to said start of said bearing profile contour (22);
• said bearing profile contour (22) is smaller than said forming profile contour (24) at least in a region which extends radially outwards from 85% of the forming area radius (RF);
• when superimposed, said bearing profile contour (22) lies completely within said forming profile contour (24);
• said bearing profile contour (22) and said forming profile contour (24) are positioned for spring back of said plastic component (46) when said screw is inserted in said component (46);
• a forming profile surface (26) which is delimited by said forming profile contour (24) and is measured in a range of 10% of said forming area radius (RF) starting from said maximum orthogonal distance of said forming profile contour (24) to said screw center axis, is larger than a bearing profile surface (28) which is delimited by said bearing profile contour (22) and is measured in a range of 10% of said forming area radius (RF) starting from said maximum orthogonal distance of said bearing profile contour to said screw center axis.

A screw (10) having a screw center axis (M), comprising:

• a drive (12) and a threaded shank (14);
• said threaded shank (14) has a thread turn (16) which partially extends along said shank in a helix of constant pitch and which forms a main thread (18) that has a thread radius (R) and a mean thread radius (RM) over its length;
• said threaded shank (14) being insertable in a plastic component (46);
• said thread radius (R) being the maximum orthogonal distance from said screw axis (M) to a profile contour of said thread turn;
• said main thread (18) has a bearing area (T) and a forming area (F);
• a forming profile contour (24) having a forming area radius (RF);
• a bearing profile contour (22) having a bearing area radius (RT);
• said forming area (F) terminating at an end point defining a forming area end (FE) of said shank;
• said main thread (18) comprises said forming profile contour (24) in said forming area (F);
• said forming area extends over an axial length of three times said mean thread radius (RM) starting from a free end (25) of said shank to said forming area end (FE), said forming area comprising said forming profile contour at said forming area end;
• said main thread (18) comprises said bearing area and said bearing profile contour (22) that extends axially over a length of said threaded shank starting at a distance of ⅔ times said mean thread radius (RM) from said forming area end (FE);
• said bearing profile contour (22) is smaller than said forming profile contour (24) at least in a region which extends radially outwards from 85% of said forming area radius (RF);
• when superimposed, said bearing profile contour (22) lies completely within said forming profile contour (24);
• a forming profile surface (26) which is delimited by said forming profile contour (24) and is measured in a range of 10% of said forming area radius (RF) starting from said maximum orthogonal distance of said forming profile contour (24) to said screw center axis (M), is larger than a bearing profile surface (28) which is delimited by said bearing profile contour (22) and is measured in a range of 10% of said forming area radius (RF) starting from said maximum orthogonal distance of the bearing profile contour to said screw center axis (M);
• and,
• said main thread (18) of said bearing area (T) is pressed against a flank of a counter thread formed into said plastic component (46) by said forming area (F) of said main thread only when said screw is fully engaged in said plastic component (46).