Hybrid induction welding process applied to piston manufacturing

Patent metadata

Field	Value
Publication number	US-9909527-B2
Application number	US-201414470200-A
Country	US
Kind code	B2
Filing date	Aug 27, 2014
Priority date	Aug 27, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A hybrid induction welded piston including an upper piston part welded to a lower piston part is provided. The piston is produced by induction heating the upper piston part and the lower piston part, and bringing the parts together to a part growth compensated position. The method then includes rotating the upper piston part 17 to 34 degrees clockwise and then 17 to 34 degrees counterclockwise. In addition to controlling the axial position and degree of rotation, the force applied to the piston parts is controlled so that preferably no flash is formed in a narrow cooling chamber of the piston. During the rotating steps, the pressure gradually increases to a maximum level which occurs while the upper piston part is rotating in the second direction. The piston includes a homogenous metallurgical bond across the weld and no indentation on the outer surface at the weld prior to machining.

First claim

What is claimed is:

1. A method of manufacturing a piston, comprising the steps of:
heating an upper joining surface of an upper piston part and a lower joining surface of a lower piston part by induction;
bringing the heated joining surfaces toward one another and allowing the heated joining surfaces to contact one another;
rotating one of the piston parts not more than 360 degrees in a first direction while the heated joining surfaces contact one another;
rotating the one piston part not more than 360 degrees in a second direction opposite the first direction while the heated joining surfaces contact one another;
applying pressure to at least one of the piston parts during the rotating steps to form a weld between the upper piston part and the lower piston part; and
the step of applying the pressure including increasing the pressure to a maximum pressure level and applying the maximum pressure level while rotating the one piston part in the second direction.

2. The method of claim 1 including applying the pressure at a level less than the maximum pressure level throughout the step of rotating the one piston part in the first direction; and obtaining and applying the maximum pressure level only during the step of rotating the one piston part in the second direction.

3. The method of claim 1 , wherein no indentation forms along an outer surface of the upper piston part and the lower piston part at the weld during the steps of bringing the joining surfaces together, rotating the one piston part, and applying the pressure.

4. The method of claim 1 , wherein no material is removed from the joining surfaces of the piston parts during the steps of allowing the heated joining surfaces to contact one another, rotating the piston parts, and applying the pressure.

5. The method of claim 1 , wherein the step of applying the pressure includes upsetting one of the joining surfaces a longitudinal distance of 0.1 to 0.6 millimeters relative to the position of the joining surface at initial contact with one another.

6. The method of claim 1 , wherein the step of applying the pressure includes gradually increasing the pressure to the maximum pressure level during the rotating steps.

7. The method of claim 6 , wherein the step of applying the pressure includes obtaining and applying the maximum pressure level only after the rotating steps are ⅝ complete and before the rotating steps are ⅞ complete.

8. The method of claim 1 including determining the maximum pressure level to be applied to the at least one of the upper piston part and the lower piston part based on at least one of an outer diameter of the upper piston part at the upper joining surface; an outer diameter of the lower piston part at the lower joining surface; an area presented by the upper joining surface; an area presented by the lower joining surface; and a desired upset of at least one of the joining surfaces after the maximum pressure level is applied.

9. The method of claim 1 , wherein the maximum pressure level is 23 N/mm 2 .

10. The method of claim 1 , wherein the rotating steps include rotating the one piston part to 17-34 degrees in the first direction; and rotating the one piston part to 17-34 degrees in the second direction.

11. The method of claim 10 , wherein the rotating steps include rotating the one piston part 25 degrees in the first direction; and rotating the one piston part 25 degrees in the second direction.

12. The method of claim 1 , wherein the rotating steps include rotating the one piston part to the same degree of rotation in the first direction and the second direction.

13. The method of claim 1 , wherein the volume of at least one of the piston parts increases from a starting volume to a final volume due to the induction heating; and the step of bringing the heated joining surfaces toward one another includes bringing the heated joining surfaces to a part growth compensated position before the volume of the at least one piston part reaches the final volume, wherein the part growth compensated position provides a space between the joining surfaces which compensates for the increase in volume.

14. The method of claim 13 including obtaining the part growth compensated position by:
(a) providing a test upper piston part formed of substantially the same material and having substantially the same geometry as the upper piston part including the upper joining surface;
(b) providing a test lower piston part formed of substantially the same material and having substantially the same geometry as the lower piston part including the lower joining surface;
(c) heating a test upper joining surface of the test upper piston part and a test lower joining surface of the test lower piston part by induction, wherein the volume of at least one of the test upper piston part and the test lower piston part increases from a starting volume to a final volume due to the induction heating;
(d) bringing the test heated joining surfaces toward one another to an estimated part growth compensated position at a constant velocity before the at least one test piston part reaches the final volume, the step of bringing the heated joining surfaces to the estimated part growth compensated position including allowing the heated joining surfaces to contact one another;
(e) monitoring an actual pressure level on the test parts for a spike in the actual pressure level;
(f) adjusting the estimated part growth compensated position based on the magnitude of an identified pressure spike and position of the test parts when the pressure spike occurs; and
(g) repeating steps (a)-(f) until a pressure spike of less than a predetermine value is identified during step (e).

15. The method of claim 14 including upsetting at least one of the joining surfaces of the test piston parts when the actual pressure level spikes; and wherein the step of adjusting the part growth compensated position includes increasing the space between the joining surfaces when the test parts are at the estimated part growth compensated position by a distance proportional to the length of the upset formed when the actual pressure spikes.

16. The method of claim 13 , wherein the step of bringing the heated joining surfaces to the part growth compensated position includes moving at least one of the upper piston part and the lower piston part axially toward the other part, and wherein only a portion of the upper joining surface contacts the lower joining surface when the piston parts are disposed at the part growth compensated position.

17. The method of claim 1 including maintaining the joining surfaces in a fixed position about a center axis while bringing the heated joining surfaces toward one another.

18. The method of claim 1 , wherein the heating step includes heating the piston parts to a temperature of 822° C. to 1,204° C. for not longer than 10 seconds and providing a heat affected zone along the weld, wherein the heat affected zone has a length of 8 to 12 micrometers.

19. The method of claim 1 including maintaining the upper piston part and the lower piston part in a fixed position about a center axis while applying pressure for 5 seconds to 15 seconds after the rotating steps.

20. The method of claim 1 , wherein the steps of applying the pressure and rotating the piston parts include welding all areas of the joining surfaces in contact with one another.

21. The method of claim 1 , wherein the radial position of the upper piston part relative to the lower piston part after applying the pre

Assignees

• Federal Mogul Corp
• Fed Mogul Llc

Inventors

• Roelofs Zachary Odel
• Martins Airton
• Evers Ross
• Garza Oscar

Classifications

• B23K13/015

  Butt welding · CPC title

• B23K20/24

  Preliminary treatment · CPC title

• F02F2003/0061

  by welding · CPC title

• B21K3/00

  Making engine or like machine parts not covered by sub-groups of B21K1/00; Making propellers or the like · CPC title

• B23K31/12

  relating to investigating the properties, e.g. the weldability, of materials · CPC title