TRANSMISSION SYSTEM COMPONENT AND METHOD FOR MAKING SAME

Abstract

A metal stamping component for a vehicle transmission system which is produced by a novel progressive tool design with enhanced performance and economic characteristics over conventional manufacturing methods.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. patent application Ser. No. 60/682,539 filed May 15, 2005, the entire subject matter of which is incorporated herein by reference.

FIELD OF INVENTION

The present application relates to a transmission system component and more specifically to a plate for use in a vehicle transmission system, and to a method for producing the transmission system plate as a metal stamping using a progressive tool design.

BACKGROUND ART

Automotive vehicles with four wheel drive capability have unique transmission system assembly designs. The components of these designs include products made of various types of metal. One such transmission system component is known as an apply plate. The apply plate component is a substantially round disc-like plate with features that provide one or more contact surfaces for the transfer of torque from the axle. The component has a center hole and teeth that act as contact surfaces.

One common prior art method of producing transmission system plate components of this type has been to cast the parts of powdered metal. A mold in the shape of the part is first produced into which powdered metal is filled. High pressure is then applied to the filled mold within a high pressure and high temperature press. The mold is then exposed to high heat to cause grain formation and solidification of the powdered metal within the mold to form the finished part.

Prior art transmission system apply plates were produced by casting the plates of powdered metal. While such transmission system components were effective in operation, they have been shown to have poor performance life with respect to fatigue, and are also relatively expensive to manufacture.

SUMMARY OF THE INVENTION

The present application discloses an improved transmission system component, including, by way of example, a transmission system apply plate and a method for making such components. It should be understood that numerous metal part components used in vehicle transmission systems may benefit from the present disclosure.

The transmission component plate embodiment of the present application has a circular body with a central opening. The body is provided with at least three tabs extending from a portion of the circumference of the circular body. The tabs are formed by cut outs within web portions of the circular body, which interconnect the tabs along the portion of the circular body circumference, and the circular body central opening. The central opening of the plate is provided within a first plane, while the circumference of the plate is provided within a second plane, which second plane is spaced from the first plane. The tabs and web portions extend intermediate the first and second planes.

The present application further provides a manufacturing process which produces a metal stamping for vehicle transmission system components, which has enhanced performance, such as increased fatigue life, and reduced manufacturing costs. The manufacturing process may include the use of progressive tool which produces a metal part which does not require secondary machining and is dimensionally acceptable as produced by the tool, and need not be further processed in secondary operations. Alternatively, a progressive tool may be used to convert a metal strip into metal parts which are required to be subsequently machined or otherwise processed to meet additional dimensional and/or performance requirements.

Another embodiment of the present application involves the production of a transmission component metal stamping by way of multiple tools where a flat piece of metal, or a blank, is formed in a first tool in a first press and then moved to secondary tools in secondary presses until a part is produced which is acceptable, or which, after subsequent machining or other processes, is acceptable.

Still another embodiment of the present process involves the production of a transmission component metal stamping from a blank which is transferred within a single press by means of a transfer system of mechanical or robotic arms, to subsequent tools within the same press, until a metal part is produced which is acceptable, or which, after subsequent machining or other processing, is acceptable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a bottom view of a prior art metal vehicle transmission system component which is a powdered metal case part;

FIG. 1b is a top view of a the prior art part of FIG. 1a;

FIG. 2a is a bottom view of the vehicle transmission system component embodiment of the present application, which is shown as a metal stamping;

FIG. 2b is a top view of the component of FIG. 2a;

FIG. 3 is a top view of the vehicle transmission system component of the present application;

FIG. 4 is a cut-away, side view of the component of FIG. 3, and taken along the line A-A of FIG. 3;

FIG. 5 is an enlarged view of a tab of the component illustrated in FIG. 3;

FIG. 6 is a schematic illustration of a top view of the metal parts being metal formed during the process performed at stations of a progressive tool using one of the methods of the present application; and

FIG. 7 is a schematic cut-away illustration of the side view of the metal parts being metal formed in FIG. 6.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE APPLICATION

The present application discloses embodiments of a new and improved vehicle transmission system component. As shown in FIGS. 2a, 2b and 3-7, the transmission component of the present application is a plate-like disc 12 having a substantially circular body 14 with a central opening 15. In the illustrated embodiment, a transmission system apply plate is shown. The body 14 is provided with at least three tabs 16 extending from a portion 18 of the circumference 20 of the circular body. In the illustrated embodiments of FIGS. 2a, 2b and 3-5, the body 14 includes five tabs 16. The tabs 16 are formed by cut outs 22 within web portions 24 of the circular body, which interconnect the tabs 16 along the portion 18 of the circular body circumference 20, and the circular body central opening 15. The central opening 15 of the plate 12 is provided within a first plane (indicated in FIG. 4)), while the circumference 20 of the plate 12 is provided within a second plane (indicated in FIG. 4), which second plane is spaced from the first plane. The tabs 16 extend along the second plane, while the cut outs 22 and web portions 24 extend intermediate the first and second planes.

The embodiment of the transmission system component plate 12 may be manufactured using a variety of metal stamping or metal forming techniques, some of which are well known in connection with the manufacture of other metal products which are unrelated to the high heat, high pressure requirements of vehicle transmission assembly systems. The use of the process of metal forming or metal stamping is a novel method of producing the transmission system components of this application.

Metal forming is the process of converting flat or two dimensional strips of metal into more complex parts. The process can be as simple as piercing holes and as complex as drawing the metal into cups and other three dimensional forms. Bending, cutting, piercing, forming and drawing are the major processes involved in metal forming.

Metal forming is a well known process which may be accomplished in a number of different ways, potentially using a number of tools within a press. The press generally includes a movable upper portion and a fixed lower portion, with the metal part being formed within the press during its engagement intermediate the upper and lower portions of the press. The upper portion of the press is generally known as a punch, and the lower portion as a die. The punch is a block of steel having a desired geometry to form a part which geometry is generally the reverse of the part to be formed, such that elements extend from the block of steel for engagement with the metal part to be formed. The die has a geometry corresponding to that of the punch, such that a concave surface or hole is present for engagement with the metal part to be formed and through which the punch travels. The flat strip of metal is placed between the punch and die, and the upper and lower portions are then pressed together under mechanical force. The source of the mechanical force may be mechanical, hydraulic, or pneumatic, as well as other methods that produce sufficient pressure to force the two portions together.

As the punch contacts the metal strip, the strip is forced into the cavities and holes of the die. The result is the deformation of the strip such that the resultant geometry matches that of the punch and/or the die geometry. This process occurs in what is known as the stroke of the press. A press is comprised of a ram, to which the punch is mounted, and a bolster to which the die is mounted. The ram is made to travel by any one of the conventional means described above and the bolster is generally fixed. As the ram travels down, called the down stroke, the punch enters the die. As the ram travels up, called the upstroke, the punch exits the die. While the ram is traveling up, the deformed metal strip is ejected from the die.

Tools can be designed to perform one action of deformation or multiple acts per stroke. A strip of metal may be formed into the geometry of a completed part in one stroke with one tool, or the part may be placed into a separate tool at a later time in order to perform more deformation for creation of a complete part. Some parts are placed into many separate dies, called line dies, positioned one after another, to produce a complete part. The necessity for multiple tools depends on a variety of well known factors, including, for example, the level of deformation, physical properties of the metal strip being deformed and/or part design.

Another method of achieving a complex level of deformation in a metal stamping is known as a progressive tool. In a progressive tool the upper portion is comprised of multiple sections arranged side by side in a line down the length of the tool. Each punch section has a corresponding die in the lower portion, or shoe, so that as the upper portion travels down, each punch lines up with and enters its matching die.

The metal strip of 1010 steel, for example, travels through the tool lengthwise, or along its longest side, and progresses a set distance forward during the upstroke of the ram. This distance is known as the progression. Each section of the progressive tool is known as a station. Each station is spaced so that the distance from each station's centerline is the distance of the progression.

The first station or section of the tool performs the first deformation of the metal strip. When the metal strip is fed during the upstroke, the first deformed portion of the metal strip reaches the next station. During the subsequent down stroke, the deformed portion of the metal strip is further deformed, and the preceding portion of the strip is simultaneously deformed at the first station. This process is repeated until with every stroke of the press, a completed part is formed and ejected at the last station of the progressive tool. A progressive tool may be comprised of as few as two stations, and as many as multiple tens of stations. The part produced is termed a metal stamping and may be exposed to subsequent operations such as machining, coating, heat treatment or other processes to improve the parts characteristics. These operations are termed secondary operations.

As mentioned above, the tool is comprised of several components. The upper and lower portions of the tool are comprised of a shoe, which is a metal block that is mounted to the ram when referring to the upper portion and the bolster when referring to the lower portion. Mounted to the shoes are the tooling sections, which may be punches, forms, dies or other types of metal forming devices which are known to those skilled in the art of metal forming. The tooling sections are generally comprised of tool steel, which are types of steel with relatively high hardness values. These tool steels are commonly processed through a heat treatment process to increase hardness. The hardness of the tool steels is desirable for performing high volume repetitions of the forming, cutting or drawing imparted on the softer strip metal comprising the stamping. These sections may also be coated with what are termed surface treatments. Surface treatments are metals or alloys which are atomically bonded to the tool steel to impart improved characteristics such as increased hardness and or reduced friction to the benefit of the service life of the tooling section.

In the embodiment of the progressive tool manufacturing process schematically illustrated in FIGS. 6 and 7, the tool is comprised of thirteen stations, each imparting a specific metal forming action or serving as an idle station. An idle station is a station of the tool where no physical work to the stamping is being performed. The purpose of an idle station may be to allow the metal of the strip to rest from a previous operation or to allow for sufficient mounting room for the adjacent stations. Details with regards to punch and die, shape, size, geometry, clearance and surface treatments will be known to those skilled in the art of tool and die making and are specific to each parts desired dimensions, geometry and material properties.

In the schematic illustration of the FIG. 6 and FIG. 7 embodiment, the first station is comprised of a punch in the upper shoe and a die in the lower shoe. The purpose of the station is to pierce a center hole in the steel strip for the purpose of what is termed pilot location in subsequent stations. Pilots are cylindrical punches mounted on the upper shoe that travel through the pilot holes in the strip to keep the steel strip in proper orientation and alignment with respect to the tool. The material metal strip M is fed into the space between the upper and lower shoe during the upward stroke of the ram and is held in general location by guides on the sides of the strip. A well known feed roller mechanism (not illustrated) is used to move the strip through the progressive tool stations. The feed rollers, one on top and one on bottom, pinch the metal strip between them and rotate to move the strip. At some point during the down stroke of the ram the feed rollers release, and the pilots of the upper shoe of the tool enter the pilot holes in the strip to ensure proper positioning of the strip at the station. The outside diameter of the pilot and the inside diameter of pilot hole in the metal strip are very close in size. Thus, the pilots orient the strip in relation to the rest of the tool so that all portions of the strip are aligned with the necessary accuracy for the metal forming processes to be completed. It is assumed that every station after the first station includes pilot punches to provide this alignment.

The center hole or central opening 15 is also provided within the transmission component plate 12, so that the plate 12 may be mounted onto the drive shaft of the vehicle transmission system assembly. The diameter of the opening 15 is calculated so as to be close to the required diameter for part functionality after the subsequent operations. For example, as the part is further formed in subsequent stations the deformation of the metal strip affects the diameter of the opening 15. Therefore, the opening 15 must be punched to a diameter which, after subsequent deformation, results in the required diameter for plate 12 performance.

In the second station, sections of the metal strip M are cut out with punches and dies to allow the part to be free of the metal strip, while leaving enough material attached to allow the part to be carried by the strip M. The purpose of this cutting is to allow material flow for subsequent metal forming operations without completely cutting the part free of the strip M. Were the plate 12 cut completely free from the strip M, some mechanical means would be required to move the part to subsequent stations. Although this is possible and in some cases may be preferable, in the present embodiment of a progressive tool, it is the action of the feed rollers moving the entire strip M forward that carries the part or plate 12. Thus, the potions of the strip M which are still in contact with the part 12 are termed carrying tabs. Also performed in this operation is the cutting out of the five tabs 16 of material from the strip M substantially in the shape if the letter “U.” This serves to produce five portions of the part termed teeth or tabs. The teeth or tabs 16 are used to engage the inner drum of the transmission assembly and transfer the load of that torque to the inner shaft thus producing rotation.

The third station is an idle station for the purposes of allowing sufficient room for the mounting adjacent tool steel sections.

The fourth station is a draw station, which is the plastic deformation and forming of the metal strip M into a concave or convex profile. The depth, profile and diameter of the area deformed are of a predetermined certain value. In this case, the radius labeled A in FIG. 3, is approximately 0.093″ on the interior and approximately 0.266″, respectively. These dimensions are of a certain value due to their affect on acceptable overall geometry of the component plate 12.

Stations five and six are re-strike stations. Re-striking is forming the metal with a punch form and die form to produce a-change in geometry. For instance in station five the re-strike serves to set the depth of the deformed section produced by the drawing operation of station four, and also to set the inner and outer radii formed in station four. In station six, the re-strike serves to bring the outer flange or circumference 20, labeled B in FIG. 4, into a desired level of flatness which is acceptable to overall part geometry.

Station seven is a cutting station where a cylindrical punch and die are used to cut excess material from the inside diameter of the center hole in the part, labeled C in FIG. 3. This serves to size the central opening 15 to acceptable part geometry.

Station eight serves to re-strike the teeth or tabs 16 of the component plate 12, labeled D in FIG. 3, to set their collective flatness with respect to acceptable overall part geometry.

Station nine is an idle station for the purpose of allowing sufficient room for the mounting adjacent tool steel sections.

Station ten is a forming station with forming punches and forming dies for the purpose of setting the collective inner diameter of the teeth or tabs 16 for acceptable overall part geometry.

Station eleven is an idle station for allowing sufficient room for the mounting adjacent tool steel sections.

Station twelve is a cutting station with cutting punches and dies for cutting the plate part 12 free from the carrying tabs allowing it to fall through a clearance hole in the lower shoe, down a chute and into a bin for subsequent handling.

Station thirteen is a cutting station with cutting punches and dies for cutting the end of the strip M. Were this station not in place, the strip M would keep feeding further through the press. Therefore, the end of the strip M is severed and allowed to fall onto a conveyor or into a take away bin as scrap metal.

The resultant plate part 12 from the process described above may be subjected to a further grinding operation on a grinding machine (not illustrated) to bring the surfaces of the part 12 into acceptable levels of flatness. The plate part 12 is then complete and is produced with enhanced performance characteristics and economics over the conventional powdered metal or metal cast transmission system components.

It is possible to produce a part that has the required flatness without the subsequent machining or grinding operation. One method would be the incorporation of what is known as a stippling operation. In this operation, an additional station of the progressive tool is provided which comprises a punch and die. The die is a hard flat piece of tool steel. The punch is machined in way that a matrix of rows and columns of spikes are produced. These spikes are machined with heights of at least 1/10^th of the steel strips material thickness and not more that ⅓^rd. The spikes enter the steel strips surface and begin a plastic deformation of the metal. Due to the fact that the other side of the metal is in firm contact with a very flat hard die surface the metal is forced to match that flat surface profile producing a level of flatness that is difficult to achieve by other methods. In the particular application of the vehicle transmission component described here, the deformation caused by the spiked punch was deemed unacceptable. However in other components of the vehicle transmission system with different flatness requirements the technique may be employed.

In other embodiments, such as those described in prior sections, the part may be produced by the movement of the part through the press by way of transfer arms or to other presses by way of human or mechanized locomotion. The use of these systems and their design will be obvious to those skilled in the art of metal forming after reading the description of the progressive tool.

The details with regards to punch and die, shape, size, geometry, clearance and surface treatments will be known to those skilled in the art of tool and die making and are specific to each parts dimension, geometry and material properties.

While the embodiments of the present invention have been described with a degree of particularity, it is intended that the disclosed embodiments would include all modifications and alterations which are known to those skilled in the art from the disclosed design and which fall within the spirit and scope of the appended claims.

Claims

1. A vehicle transmission system component having a generally circular plate-like body having a circumference portion and a central opening spaced from the circumference portion,

five tabs extend from said circumference portion toward said central opening being formed by cut outs within web portions formed within said body,

said web portions interconnect said circumference portion of the body with a portion of the body having said central opening,

said central opening being provided within a first plane of the body and the circumference portion of the plate being provided within a second plane of the body, with said second plane being spaced from the first plane, and

said tabs extending within the second plane and said cut outs and web portions extending intermediate the first and second planes.

2. A method for manufacturing a vehicle transmission system component comprising the steps of:

providing an elongate metal strip of raw material to a progressive tool;

at a tool station, cutting a central opening within said metal strip;

moving said strip to a tool station and cutting out certain unnecessary portions of said metal strip to provide a component having an external shape with a substantially circular body, said body having a circumference portion, cut out sections forming at least three tabs, and web portions extending intermediate said tabs and interconnecting said circumference portion and said body portion supporting said central opening;

moving said strip to a tool station for forming said body portion supporting said central opening to a first plane and said circumference portion to a second plane spaced from said first plane, with said web portions have a predetermined desired radius; and

moving said strip to a tool station for cutting the component free from the metal strip.