FORMED OUTER ARM FOR ROCKER ARM ASSEMBLY
A method of cold forming an outer arm of a rocker arm assembly in a cold forming machine includes providing a slug having a first end and a second end, extruding the slug at the first end to establish two different widths of the slug, compressing the slug to form an upper angled surface and a lower angled surface at the second end, and compressing the slug to form an inner arm window defined by a pair of side walls and a pair of end walls.
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This application is a continuation of International Application No. PCT/EP2020/025055 filed Feb. 7, 2020, which claims the benefit of Indian Patent App. No. 201911004826, filed Feb. 7, 2019, the contents of which are incorporated herein by reference thereto.
FIELDThe present disclosure relates generally to rocker arms for internal combustion engines and, more particularly, to cold, warm, and hot forming outer arms for rocker arm assemblies.
BACKGROUNDSwitching rocker arms have been used to alter the operation and performance of internal combustion engines. For example, specialized rocker arms may be used to provide variable valve actuation (WA) such as variable valve lift (WL) and cylinder deactivation (CDA). Such mechanisms are developed to improve performance, fuel economy, and/or reduce emissions of the engine. Several types of the WA rocker arm assemblies include an inner rocker arm within an outer rocker arm that are biased together with torsion springs.
Switching rocker arms allow for control of valve actuation by alternating between latched and unlatched states. A latch, when in a latched position causes both the inner and outer rocker arms to move as a single unit. When unlatched, the rocker arms are allowed to move independent of each other. In some circumstances, these arms can engage different valve lift profiles, such as low-lift, high-lift, and no-lift (or lost motion). Mechanisms are required for switching rocker arm modes in a manner suited for operation of internal combustion engines.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
SUMMARYIn one aspect, a method of cold forming an outer arm of a rocker arm assembly in a cold forming machine is provided. The method includes providing a slug having a first end and a second end, extruding the slug at the first end to establish two different widths of the slug, compressing the slug to form an upper angled surface and a lower angled surface at the second end, and compressing the slug to form an inner arm window defined by a pair of side walls and a pair of end walls.
In addition to the foregoing, the described method may include one or more of the following features: rotating the slug approximately 90° between extruding the slug and compressing the slug to form the upper and lower angled surfaces; wherein the step of extruding the slug at the first end includes providing a punch force substantially along a longitudinal axis of the slug; and wherein the step of compressing the slug to form the upper and lower angled surfaces includes providing a punch force substantially orthogonal to the longitudinal axis.
In addition to the foregoing, the described method may include one or more of the following features: compressing the slug to form the second end with a pivot body including an interfacing seat configured to engage a hydraulic lash adjuster, wherein the first end is configured to engage an engine valve; punching the slug to remove a bottom wall of the slug to further form the inner arm window; forming at least one pair of axle holes in the pair of side walls; wherein the slug is heated and warm or hot formed prior to cold forming; and wherein the providing a slug includes shearing wire to a desired length to form the slug.
In one aspect, method of cold forming an outer arm of a rocker arm assembly using a cold forming machine having six forming stations is provided. The method includes shearing wire to a desired length to form a slug having first and second ends, at the first forming station, extruding the slug and flattening the first end, and at the second forming station, compressing the slug to form the second end with an upper angled surface and a lowered angled surface. The method further includes at the third forming station, compressing the slug to form an inner arm window defined by a pair of side walls, a pair of end walls, and a bottom wall, at the fourth forming station, compressing the slug to form the second end with a pivot body including an interfacing seat configured to interface with a hydraulic lash adjuster, at the fifth forming station, punching the slug to remove the bottom wall, and at the sixth forming station, forming the slug to final workpiece dimensions.
In addition to the foregoing, the described method may include one or more of the following features: wherein the forming the slug to final workpiece dimensions includes forming a first pair of axle holes in the pair of side walls; wherein the forming the slug to final workpiece dimensions further includes forming a second pair of axle holes in the of side walls; heating the slug prior to the first forming station; warm or hot forming the slug in the first, second, third, and fourth forming stations, and cold forming the slug in the remaining forming stations; and a seventh forming station where the slug is cooled and coined after the fourth forming station and before the fifth forming station.
In addition to the foregoing, the described method may include one or more of the following features: rotating the slug approximately 90° between the first forming station and the second forming station; wherein the first forming station provides a punch force substantially along a longitudinal axis of the slug; wherein the second forming station provides a compressing force substantially orthogonal to the longitudinal axis; wherein the third forming station provides a compressing force substantially orthogonal to the longitudinal axis; and wherein the second forming station, the third forming station, the fifth forming station, and the sixth forming station each provide a compressive force substantially orthogonal to the longitudinal axis.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
Described herein are systems and methods for forming a component of a rocker arm assembly such as, for example, an outer arm. In one example, the described components are cold formed/forged to near net shape as an alternative manufacturing process to conventional high-cost casting, thereby enabling complex metal forming with reduced overall cost. In another example, the described components are first warm or hot formed/forged and then subsequently cold formed/forged.
With reference to the figures, various methods and processes are described for forming the component (e.g., an outer arm) of a rocker arm assembly such as, for example, a switching roller finger follower (SRFF) assembly 10. In the example embodiment shown in
With continued reference to
In the example embodiment, the inner arm 12 and the outer arm 14 are both mounted to a pivot axle 20, which secures the inner arm 12 to the outer arm 14 while also allowing a rotational degree of freedom pivoting about the pivot axle 20 when the SRFF assembly 10 is in a deactivated state. A lost motion torsion spring 22 is secured to the pivot axle 20 and is configured to bias the position of the inner arm 12 so that it always maintains continuous contact with a camshaft lobe (not shown).
As shown in
As illustrated, the inner arm 12 is disposed between the first outer side arm 30 and the second outer side arm 32. The inner arm 12 includes a first inner side arm 40 and a second inner side arm 42. The first and second inner side arms 40, 42 each include an aperture 44 configured to receive the bearing axle 36 therethrough. An inner roller 48 is supported by the bearing axle 36.
As used herein, the term “cold forming” is intended to encompass what is known in the art as, for example, “cold forging,” “cold heading,” and “deep drawing.” As used herein, the term “machining” means the use of a chucking machine, drilling machine, turning machine, grinding machine, broaching machine or other such machine to remove material. In other examples, one or more portions of the manufacturing methods or processes described herein include warm forming or warm forging and/or hot forming or hot forging. In one example, cold forming is a metal forming process carried out at or near room temperature, warm forming is a metal forming process carried out above the cold forming temperature but below a recrystallization temperature or transition temperature of the metal, and hot forming is a metal forming process carried out above the recrystallization temperature of transition temperature of the metal.
Illustrated in
With reference to
At the second forming station 220 (
At the third forming station 230 (
At the fourth forming station 250 (
Accordingly, the cold formed outer arm blank 50 includes all of the structural features of the finished outer arm 14 described above and shown in
With reference now to
In one example, the punch force produced at the first forming station 210 is between 15 tons and 35 tons or between approximately 15 tons and approximately 35 tons. In another example, the punch force produced at the first forming station 210 is 25 tons or approximately 25 tons. In one example, the punch force produced at the second forming station 220 is between 200 tons and 225 tons or between approximately 200 tons and approximately 225 tons. In another example, the punch force produced at the second forming station 220 is 212 tons or approximately 212 tons. In one example, the punch force produced at the third forming station 230 is between 650 tons and 750 tons or between approximately 650 tons and 750 tons. In another example, the punch force produced at the third forming station 230 is 679 tons or approximately 679 tons.
In one example, the punch force produced at the fourth forming station 250 is between 200 tons and 230 tons or between approximately 200 tons and 230 tons. In another example, the punch force produced at the fourth forming station 250 is 214 tons or approximately 214 tons. In one example, the punch force produced at the fifth forming station 260 is between 0.5 tons and 1.5 tons or between approximately 0.5 tons and 1.5 tons. In another example, the punch force produced at the fifth forming station 260 is 0.8 tons or approximately 0.8 tons. In one example, the punch force produced at the sixth forming station 270 is between 0.1 tons and 0.5 tons or between approximately 0.1 tons and 0.5 tons. In another example, the punch force produced at the sixth forming station 270 is 0.3 tons or approximately 0.3 tons.
In an alternative method of manufacture, outer arm blank 50 is formed in a seven station process (e.g., similar to
With reference now to
Illustrated in
With continued reference to
At the second forming station 320 (
At the third forming station 330 (
At the fourth forming station 350 (
The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Claims
1. A method of cold forming an outer arm of a rocker arm assembly in a cold forming machine, the method comprising:
- providing a slug having a first end and a second end;
- extruding the slug at the first end to establish two different widths of the slug;
- compressing the slug to form an upper angled surface and a lower angled surface at the second end; and
- compressing the slug to form an inner arm window defined by a pair of side walls and a pair of end walls.
2. The method of claim 1, further comprising rotating the slug approximately 90° between extruding the slug and compressing the slug to form the upper and lower angled surfaces.
3. The method of claim 1, wherein the step of extruding the slug at the first end includes providing a punch force substantially along a longitudinal axis of the slug.
4. The method of claim 3, wherein the step of compressing the slug to form the upper and lower angled surfaces includes providing a punch force substantially orthogonal to the longitudinal axis.
5. The method of claim 1, further comprising compressing the slug to form the second end with a pivot body including an interfacing seat configured to engage a hydraulic lash adjuster, wherein the first end is configured to engage an engine valve.
6. The method of claim 1, further comprising punching the slug to remove a bottom wall of the slug to further form the inner arm window.
7. The method of claim 1, further comprising forming at least one pair of axle holes in the pair of side walls.
8. The method of claim 1, wherein the slug is heated and warm or hot formed prior to cold forming.
9. The method of claim 1, wherein the providing a slug includes shearing wire to a desired length to form the slug.
10. A method of cold forming an outer arm of a rocker arm assembly using a cold forming machine having six forming stations, the method comprising:
- shearing wire to a desired length to form a slug having first and second ends;
- at the first forming station, extruding the slug and flattening the first end;
- at the second forming station, compressing the slug to form the second end with an upper angled surface and a lowered angled surface;
- at the third forming station, compressing the slug to form an inner arm window defined by a pair of side walls, a pair of end walls, and a bottom wall;
- at the fourth forming station, compressing the slug to form the second end with a pivot body including an interfacing seat configured to interface with a hydraulic lash adjuster;
- at the fifth forming station, punching the slug to remove the bottom wall; and
- at the sixth forming station, forming the slug to final workpiece dimensions.
11. The method of claim 10, wherein the forming the slug to final workpiece dimensions includes forming a first pair of axle holes in the pair of side walls.
12. The method of claim 11, wherein the forming the slug to final workpiece dimensions further includes forming a second pair of axle holes in the of side walls.
13. The method of claim 10, further comprising heating the slug prior to the first forming station.
14. The method of claim 13, further comprising warm or hot forming the slug in the first, second, third, and fourth forming stations, and cold forming the slug in the remaining forming stations.
15. The method of claim 14, further comprising a seventh forming station where the slug is cooled and coined after the fourth forming station and before the fifth forming station.
16. The method of claim 10, further comprising rotating the slug approximately 90° between the first forming station and the second forming station.
17. The method of claim 10, wherein the first forming station provides a punch force substantially along a longitudinal axis of the slug.
18. The method of claim 17, wherein the second forming station provides a compressing force substantially orthogonal to the longitudinal axis.
19. The method of claim 17, wherein the third forming station provides a compressing force substantially orthogonal to the longitudinal axis.
20. The method of claim 17, wherein the second forming station, the third forming station, the fifth forming station, and the sixth forming station each provide a compressive force substantially orthogonal to the longitudinal axis.
Type: Application
Filed: Aug 5, 2021
Publication Date: Nov 25, 2021
Applicant: Eaton Intelligent Power Limited (Dublin)
Inventors: Michael Halsmer (Marshall, MI), Vinod Kumar Mannaru (Pune), Matthew Vance (Kalamazoo, MI)
Application Number: 17/394,687