TWO-STEEL SCREW WITH AN EXTRUSION CONNECTION AND METHOD FOR PRODUCING SAID SCREW

• US 20170074311A1
• Filed: 02/10/2015
• Published: 03/16/2017
• Est. Priority Date: 03/12/2014
• Status: Active Grant

• Current Assignee: EJOT GmbH & Company KG (EJOT Holding GmbH & Company KG)
• Original Assignee: EJOT GmbH & Company KG (EJOT Holding GmbH & Company KG)
• Inventors: GROTMANN, Dieter, KETTNER, Tobias
• Granted Patent: US 10,451,101 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B21K 1/44 bolts, studs, or the like making screw-thread B21K1/56; making U-bolts B21K1/74
• CPC Class Codes: B21K 1/56 screw-threaded elements
• CPC Class Codes: B21K 25/00 Uniting components to form integral members, e.g. turbine wheels and shafts, caulks with inserts, with or without shaping of the components uniting by interference- or press-fitting B23P11/02, B21K19/02
• CPC Class Codes: F16B 25/0094 the screw being assembled or manufactured from several components, e.g. a tip out of a first material welded to shaft of a second material
• CPC Class Codes: F16B 25/103 by means of a drilling screw-point, i.e. with a cutting and material removing action
• CPC Class Codes: F16B 35/00 Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws F16B33/008 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275; using screws with adjustment sleeves F16B5/0283; thread cutting screws F16B25/00

Abstract

The invention relates to a two-steel screw comprising a top part and a cutting part, the top part consisting of a corrosion-resistant material and having a screw head and a shank portion, and the cutting part consisting of a hardenable material, the top part being permanently connected to the cutting part in the region of the shank portion by way of impact extrusion.

Claims

1. A two-steel screw (10) comprising a top part (12) and a cutting part (14), the top part (12) consisting of a corrosion-resistant material and having a screw head (16) and a shank portion (18), and the cutting part (14) consisting of a hardenable material, wherein the top part (12) is permanently connected to the cutting part (14) in the region of the shank portion (18) by way of impact extrusion.

2. The two-steel screw (10) according to claim 1, wherein the cutting part (14) has a lug-like projection (34) and that the top part (12) has a cup-shaped recess (24) on the shank portion (18), wherein the lug-like projection (34) is arranged in the cup-shaped recess (24) and axially undercuts the top part (12) in the region of the cup-shaped recess (24) at least partially.

3. The two-steel screw (10) according to claim 2, wherein the lug-like projection (34) fills the shape of the cup-shaped recess (24) completely.

4. The two-steel screw (10) according to claim 1, wherein the cutting part (14) is hardened and has at least one drill bit.

5. The two-steel screw (10) according to claim 2, wherein, in cross-section, the cup-shaped recess (24) has an engaging profile (68) with a plurality of, preferably three, engaging segments (72),

6. The two-steel screw (10) according to claim 5, wherein circular segments (70) are provided between the engaging segments (72).

7. The two-steel screw (10) according to claim 5, wherein the engaging segments (72) and the circular segments (70) are arranged at an angle (74) of 120°

relative to one another in the circumference of the recess (24).

8. The two-steel screw (10) according to claim 5, wherein the cup-shaped recess (24) has a first radius (76) in the region of the circular segments (70) and has a second reducing radius (78) which is smaller than the first radius (76) in the region of the engaging segments (72).

9. A method for producing a two-steel screw (10) consisting of a top part (12) made of a corrosion-resistant material and having a screw head (16) and a shank portion (18), and a cutting part (14) consisting of a hardenable material, comprising:

pressing a cup-shaped recess (24) with a predetermined depth (26) into the top part (12) in the region of the shank portion (18) or forming a lug-like projection with a predetermined length on the shank portion (18);

producing the cutting part (14) with a lug-like projection (34) with a length (38) greater than the depth (26) of the recess (24) or pressing a cup-shaped recess into the cutting part (14) with a depth smaller than the length of the lug-like projection of the shank portion (18);

introducing the projection (34) into the recess (24) and connecting the top part (12) and the cutting part (14) by means of impact extrusion, so that the lug-like projection (34) completely fills the shape of the cup-shaped recess (24).

10. The method according to claim 9, wherein the cup-shaped recess (24) is pressed into the top part (12) or into the cutting part (14) in an area ratio of approximately 55% to approximately 75% to a cross-sectional area of the shank portion (18).

11. The method according to claim 9 wherein the lug-like projection (34) is produced in a circular cylindrical shape.

12. The method according to claim 9, wherein when the cup-shaped recess (24) is pressed in, an engaging profile (68) with engaging segments (72) is pressed in.

13. The method according to claim 9, wherein after the connection a thread is rolled onto the shank portion (18) and the cutting part (14).

14. The method according to claim 9, wherein the top part (12) and the cutting part (14) are arranged axially in alignment before connection.

15. The method according to claim 9, wherein the production of the cutting part (14) and the connection to the top part (12) are carried out in a multi-stage press.