초록 ▼

Screw made of plastic for screwing into a material of low strength, e.g. rigid foam plastic, having a deep thread compared with the screw shank, the screw shank running out conically into a screw point. The screw has the following features:1. the depth of thread H and the minor diameter Dk of the th

Screw made of plastic for screwing into a material of low strength, e.g. rigid foam plastic, having a deep thread compared with the screw shank, the screw shank running out conically into a screw point. The screw has the following features:1. the depth of thread H and the minor diameter Dk of the thread form a quotient Q1=H/Dk in the order of magnitude of 1 to 3.5, preferably 2;2. the minor diameter Dk and the thread pitch P form a quotient Q2=Dk/P in the order of magnitude of 0.3 to 0.6, preferably 0.5;3. the thread is designed as a V-thread having a vertex angle of the thread teeth of less than 30°.

대표청구항 ▼

1. Screw (1) made of plastic for screwing into a material of low strength having a screw shank (2) defining a minor diameter and a thread (6) having a certain pitch (P) and a large depth (H) as compared with the screw shank (2), the screw shank running out conically into a screw point (21), characte

1. Screw (1) made of plastic for screwing into a material of low strength having a screw shank (2) defining a minor diameter and a thread (6) having a certain pitch (P) and a large depth (H) as compared with the screw shank (2), the screw shank running out conically into a screw point (21), characterized by the screw having a main portion wherein any part of the main portion has the combination of the following features:1. the depth of thread (H) and the minor diameter (Dk) of the thread form a quotient Q1=H/Dk in the order of magnitude of 1 to 3.5; 2. the minor diameter (Dk) and the thread pitch (P) form a quotient Q2=Dk/P in the order of magnitude of 0.3 to 0.6; 3. the thread (6) is designed as a V-thread having a vertex angle of the thread teeth of less than 30°. 2. Screw (7, 13) made of plastic for screwing into a material of low strength having locking elements (8, 14, 19) which are arranged in a thread region and make slackening-back of the screw (7, 13) more difficult, according to claim 1, characterized in that the locking elements (8, 14, 19) are held in a pivotable manner by film hinges (9, 20) which project from the screw material in the relieved position, swing into a recess (11, 16) in the screw material when the screw (7, 13) is being screwed in and spring out of this recess (11, 16) when the screw is being slackened back.3. Screw according to claim 2, characterized in that the locking elements (8) are let into thread turns (10).4. Screw according to claim 2, characterized in that the locking elements (14, 19) are let into a thread root (15).5. Screw according to claim 1, characterized in that the quotient Q1=H/Dk is in the order of magnitude of 1.5 to 3.5.6. Screw according to claim 1, characterized in that the quotient Q1=H/Dk is in the order of magnitude of 2 to 3.5.7. Screw according to claim 1, characterized in that the quotient Q2=Dk/P is in the order of magnitude of 0.5 to 0.6.