This invention relates to the art of manufacturing parts using sheet metal blanks and forming dies and more particularly to new and improved constructions and techniques for the superplastic forming of metal parts with rapid and trouble free extraction of formed parts from forming dies.
Prior to the present invention, various types of forming equipment and processes have been developed for quantity production improvements to shape blanks of metallic materials into a wide range of items. Among such equipment and processes are super and quick plastic forming dies and processes in which a ductile sheet of superplastic metal alloy is heated and stretched onto the forming surfaces of heated dies to produce high-quality, light-weight parts such as panels for automotive vehicles. Often such sheets are quite large so that trunk lids, engine hoods or other large panels can be formed in one piece. Examples of such processes and equipment are found in U.S. Pat. No. 5,974,847 issued Nov. 2, 1999 to Sanders et al for Superplastic Forming Process and U.S. Pat. No. 5,819, 572 issued Oct. 13, 1998 to P. E Krajewski for Lubricating System For Hot Forming, both assigned to the assignee of this invention and both hereby incorporated by reference.
In the patent to Sanders et al. a blank sheet of metal alloy is heated to a superplastic forming temperature and is pulled over and around a forming insert in a die set. Subsequently using differential gas pressure, the sheet is further stretched into conformity with a forming surface of the insert so that thinning of the formed part is minimized. In the patent to Krajewski, dry lubricant is applied to a metallic sheet which is subsequently heated to predetermined forming temperatures and formed into a part in superplastic forming die equipment. The lubricant initially provides improved forming of the part and subsequently improved release of the formed part from the forming die.
Formed part removal is further addressed in copending patent application Ser. No. 09/837,597 filed Apr. 19, 2001 by R. Kleeber et al for Panel Extraction Assist for Super and Quick Plastic Forming Equipment assigned to the assignee of this invention and hereby incorporated by reference. In the above-identified application, forming pressures used for making superplastic parts in hot forming dies are further employed for improved ejection of the part from the forming die.
While the above identified patents and patent application constructions provide improvements in super and quick plastic forming they often do not attain new and higher standards for the production of such formed parts with minimized part rejection from part distortion resulting from part ejection forces. More particularly with some equipment, difficulties have been experienced in quantity production in accurately positioning the blanks or sheets onto the forming die and then subsequently removing the formed part or panel without distortion or other damage from release or ejection forces.
The employment of guide pins and cooperating guide pin slots for the forming die and blank sheet respectively to precisely position the blank sheet on the forming die has only met with limited success in view of the fact that the material of the blank expands or otherwise distorts during the forming process and grips onto the guide and positioning pin. This gripping inhibits removal of the formed panel from the die. Often the formed panel is distorted to such an extent by the part ejection forces moving the part from the pin and the associated forming die that the panel has to scrapped and recycled.
In contrast the prior art, the present invention is drawn to new and improved methods and constructions that provides improved blank positioning on the forming die and improved formed parts. This invention importantly meets higher standards for ejection and removal of high quality formed parts from hot super plastic and quick plastic forming dies particularly while in the press and operating at elevated temperatures. More particularly, the invention is directed to the quick and effective removal of super plastically formed parts from hot forming dies without part damage.
The present invention specifically alleviates blank guidance and formed part removal problems by providing a new and improved guide pin slot configurations that have adequate in-plane stiffness for blank locating purposes. The configurations further provides discrete offal or waste areas in the part responsive to removal forces particularly those angled to the plane of the part to allow limited and controlled bending of such predetermined and specific waste areas of the part to enhance part removal from the forming die.
This invention provides a new and improved positioning and guide slot arrangement in a blank of formable sheet material such as aluminum alloy which is engineered to cooperate with an upstanding blank locating and positioning guide pin of a forming die that augments removal of a formed part from the die. When the formed part is being ejected a guide pin slot in a sacrificial or waste part of the formed member is frictionally engaged by the surface of the pin that effects the bending of the waste part that turns away from the guide pin and effects enlargement of the pin guide slot to enhance release of the formed part from the forming die and the guide pin thereof.
It is a feature, object and advantage of this invention to provide a new and improved guide pin slot arrangement in a blank of sheet metal to be formed into a part of predetermined shape that allows the controlled deformation of specific waste areas of the part containing the slot arrangement on removal from the guide pin of the forming die. In this invention side walls in the waste area defining the guide pin slot can physically contact the guide pin as the formed part is being removed from the die to cause the waste portion to bend along a predetermined bend line so that the guide pin is clear of the part to thereby augment part removal without part distortion or other damage.
Another feature object and advantage of this invention is to provide new and improved blank positioning and guide pin slot arrangement in a blank of sheet material used in superplastic forming that augments removal of a part formed from the blank on a forming die having a guide pin that cooperates with the guide pin slot to accurately position the blank on the forming die.
Another feature object and advantage of the present invention is to provide a new and improved guide pin slot arrangement in a blank to be superplastically formed that prevents the gripping of the formed part onto a guide pin carried by the forming equipment to allow the formed part to be easily removed from the equipment by part extraction forces.
In a preferred form of the invention a centralized guide pin receiving slot is bounded on either side by edge slots that extend from predetermined positions in the periphery of the blank to predetermined terminal points to thereby establish specific bend lines or hinges in the blank that easily bend under load when the part is removed from a forming die to enlarge the pin slot to augment removal of the part from the guide pin and the associated die.
These and other objects, advantages and features of the invention will become more apparent from the following detailed description of one preferred embodiment of the invention and drawing in which:
a is a plan view of a portion to the sheet metal blank of
b is a plan view similar to the view of
Turning now in greater detail to the drawing,
The ram plate 16 is cycled by hydraulic cylinders 22 from the illustrated open position shown in
As best shown in
The lower tool or forming die 14 extends upwardly from support by the face of the bolster plate 12 and has a rectilinear peripheral wall terminating in a flattened end face 36 for support of the alloy sheet 24 when loaded thereon. The lower tool further comprises a thick main forming body profiled to form the desired configuration of the part being produced. As best shown in
The guide pin 40 is further designed to be operatively received in a guide and positioning slot arrangement 46 formed in the sheet 24 in an area which is to be subsequently removed or concealed in the final use of the formed part. More particularly the guide and positioning slot arrangement has a main channel 48 which is generally rectilinear and is in part defined by opposing straight sides 50 spaced at a width which is slightly greater than the diameter of the cylindrical guide pin 40. The main channel of the guide pin slot arrangement extends through the peripheral edge 34 of the blank and defines an open gate 52 for receiving the guide pin so that the sides can contact and guide the sheet onto the forming die. The main channel further extends to a terminal inboard edge or end 56 that may be horizontal or curved to fit the periphery of the pin to make an effective stop for the upstanding pin 46 so that the blank being guided by the slot is positioned at a predetermined location on the forming die with precision to augment the forming of an acceptable formed part.
The inboard end of the slot communicates with left and right side branches 58 and 60 that extend at predetermined angles from direct communication with the end of the guide pin channel. The overall shape of the main channel and the mirror-imaged side branches may define an Y shaped configuration although other configurations, such as a T-shape could be used. These branches cooperate with left and right side boundary slots 62, 64 generally parallel to and offset to either side of the main channel 48. The boundary slots, the pin channel, and its branches cooperate to define left and right side offal or waste parts 66,68 of the blank. More particularly these portions are further defined by left and right side live hinges or bend lines 70,72. The hinges 70,72 are generally linear, intentionally weakened bend lines which extend from respective ends of the side branches to the associated ends or terminal points of the left and right side boundary slots 62 and 64 to allow controlled bending of the waste parts or offal 66,68 away from the guide pin and thereby augment removal of the formed panel or part from the forming die without bending of the formed areas of the parts or other damage.
In operation of a preferred embodiment, a robot 80 or other suitable loading unit turns and lowers an operating arm 82 thereof to pick up a top sheet or blank 24 from a stacked supply 84 of blanks. The arm 82 of the robot moves forwardly from the elevated position illustrated in
The ram plate then moves downwardly so that the upper tool establishes operative sealing engagement with the heated blank seated on the die. Appropriate forming pressure is then fed into the forming chamber of the upper tool for part forming. The part is superplastically formed as is known in this art and the upper tool is subsequently raised to expose the formed part on the die. The arm 88 of a second robot 90 or other suitable unloading tool is moved into the opened forming equipment to pick up the hot formed part 28 that has a facsimile of the profile of the forming tool 14.
As the part is picked up by the robot arm 88 or otherwise ejected from the forming either die either or both sacrificial parts or offal 66,68 of the formed part may be bent downwardly. This may occur because of frictional contact of the pin 40 with either or both sides 50,50 of the guide pin channel as the formed part is moved off of the forming die. Part flow arrow B diagrammatically illustrates the unencumbered removal of a finished part from the forming die. For example, the waste part or offal 68 shown in
The waste part 68 is accordingly displaced by direct contact with the guide and positioning pin as the formed part 28 is moved off of the forming die by part ejection forces. This turning movement of the waste part significantly enlarges the guide pin —main slot clearance such as diagrammatically illustrated at 94 in
In contrast,
In any event, such deformation is substantially obviated with the new guide pin slot arrangement of this invention so that large numbers of identically formed parts can be successfully made with no adverse part deformation or bending and with minimized part rejection.
While the bend lines 72 are shown as being angled from the horizontal in
While some preferred methods and mechanisms have been disclosed to illustrate this invention, other methods and mechanisms embracing this invention will now be apparent to those skilled in the art. Accordingly, the scope of the invention is to be considered limited only by the following claims.
Number | Name | Date | Kind |
---|---|---|---|
2975818 | Rippe | Mar 1961 | A |
3854359 | Tagami | Dec 1974 | A |
5259230 | Beyers | Nov 1993 | A |
5604044 | McCabe et al. | Feb 1997 | A |
5819572 | Krajewski | Oct 1998 | A |
5974847 | Saunders et al. | Nov 1999 | A |
6085571 | Brinas et al. | Jul 2000 | A |
20020152783 | Kleber et al. | Oct 2002 | A1 |
Number | Date | Country | |
---|---|---|---|
20040050128 A1 | Mar 2004 | US |