Automated cure press closure system and method

Abstract

 An automated shimming device (70, 72) and method for use with a form and cure press is shown. The shimming device (70, 72) is composed of a plurality of contiguous wedge sets. The wedge sets are disposed between two dc servo drive (113, 119) and linear activator (115, 123) assemblies. One servo drive (113) is an UP drive which urges all lower wedges (85) laterally which in turn force the upper wedges (71) to travel vertically along inclined planes which slide along corresponding inclined planes on the lower wedges. A similar downward motion is performed by a DOWN drive (119). The wedge sets form a bottom surface to close the gap between the lower pressing bar (66) and an upper curing mold (36) of a form and cure press assembly. The wedges assure desired dimensional tolerances in the materials (47, 49) being cured and formed.

Description

[0001] This invention relates generally to pressure curing of wound coils. More particularly, the invention relates to an adjustable closure system for closing a cure press which obviates the need for manufacturing and placing separate shimming members in the press.

[0002] Hydraulic-pneumatic presses with heated dies are used to form and cure coils such as superconducting coils. The coils must be formed to prescribed configurations with sufficient accuracy to provide the required performance characteristics. Superconducting coils have recently become very important for use in building magnets for particle accelerators and the like. Extensive development of such coils has occurred in order that such magnets can be used in industry. Forming and curing of acceptable coils has been generally difficult due to the requirement of high accuracy of coil dimensions.

[0003] An apparatus and process for forming and curing such coils is disclosed in commonly-owned U.S. Application Serial No. 07/360,192, filed June 1, 1989, entitled "Apparatus and Process for Making a Superconducting Magnet for Particle Accelerators." The equipment used includes a fifty-five foot curing mold which has an arc-shaped internal mold area which is suspended above a pressing assembly. A winding mandrel is mounted on a pressing plate between two upstanding shoulders which form pressing bars. Coil material is loaded between an end of each pressing bar and a keystone-shaped member mounted on an alignment shaft extending from the upper platen of the press. The pressing plate moves upwards thus moving the winding mandrel and the pressing bars with the coil material loaded above the pressing bars towards the mold until the coil material and pressing bars are received in mating relationship with the inner arc-shaped area of the cure mold. Thus, the mold contacts with the outer surface of the coil material. An alignment shaft is typically provided to assure proper placing of the coil material in the mold.

[0004] After alignment takes place, the pressing plate continues to advance forward until the winding mandrel is fully loaded into the form and cure press. With a pneumatic pressure assembly, a hydraulically powered seating cylinder lifts the mandrel-pressing bar-coil subassembly and firmly seats it into the upper platen of the curing mold.

[0005] A shimming process is then performed to close a gap which is created between the bottom of the cure mold and the pressing plate. Conventionally, the shimming process has been performed manually. This involves raising the system temperature to about 90°C and a fixed pressure is applied to the coils. As this temperature and pressure are held, operators measure the critical distance between the lower pressing plate and the mold. A mean gap is then calculated. The mean gap dimension is inserted into an equation and a suitable shim dimension is calculated. The shims are used in the press between the bottom of the mold and the pressing plate to assure that the cured coil will be of proper dimension given variations in coil material.

[0006] Once the proper dimension is determined, in the conventional process, the shim material is cut. The shims are typically composed of a spring steel shim stock. The entire form and cure press is about fifty feet long, therefore, many separate shorter strips of shimming material are cut and affixed to one another with KAPTON tape of about 1 mil in thickness to create a fifty foot shim. Such a shim must be made for each side of the press. Once the shims are constructed, several operators are required to carry the long strip to the form and cure press and to load it between the press bed and the mold. Thereafter, the temperature is increased to 150°C and the pressure is raised to 15,000 psi on the coil. The pressing plate bottoms against the shim and holds the dimensions as desired. The temperature is held for about one hour. A cool down process is then commenced and the entire process is reversed.

[0007] The process of manually cutting and constructing the shims and placing the shims in the mold requires intensive manual labor. The entire forming and curing process must be placed on hold while the shims are being made. The preparation of the shims can take several hours. New shims must be made each time a set of coils is produced. Further, the manual process has risk and can result in inconsistent quality.

[0008] There is a need, therefore, for an automated shimming mechanism which results in shorter press cycles, and greater consistency and quality of coils produced.

[0009] These and other needs are satisfied by the present invention which comprises an automated shimming device driven by dc servo drives which are controlled by a microcomputer. The shimming device comprises a series of hardened tool steel wedge members placed between the full length of the upper cure mold and the lower pressing plate. Two such shimming devices are required, one for each side of the press. The wedge members are provided in contiguous sets of two wedges comprising an upper wedge and a lower wedge. The upper and lower wedges have corresponding inclined planes which slidingly engage one another. When a lower wedge member is moved laterally, the corresponding upper wedge member slides along the inclined plane of the lower member and moves vertically, resulting in an overall upward or downward motion of the upper wedge member. The wedge members also urge contiguous wedge members to move in the same direction. In this way, the entire assembly is moved upwards or downwards. A slot and pin arrangement is provided on the upper wedge members to restrict motion of the upper wedge member to vertical motion. The wedge sets are permanently located between the lower press plate and each side of the mold portion which extends downwards to the press plate. During the form and cure process the wedge sets can be moved upwards a sufficient distance to close the gap between the upper and lower mating members of the press. More particularly, the flat upper surfaces of the contiguous upper wedges form the shim which adjusts the gap and thereby restricts closure of the press in any manner desired in a particular application.

[0010] The lower wedges for each side of the press are constantly in compression between two dc servo drives which are placed at either end of the line of wedge sets. One servo drive commands an associated linear activator to extend its drive arm thereby moving the endmost lower wedge member laterally away from the servo drive and towards the other lower wedge members. This in turn causes each lower wedge member to communicate this motion to the next lower wedge member and the entire assembly moves a given distance in a particular direction. The other servo drive member can command a second linear activator to move the endmost wedge at the opposite end a predetermined distance in the opposite direction. One of the servo drives associated with the lower wedge members is the UP drive and the other servo drive is the DOWN drive.

[0011] A microcomputer is suitably programmed and calibrated to command the servo drives to appropriately adjust the shimming device to close the gap entirely. Then, based on the distance travelled, an optimum setting is calculated by the computer and the DOWN drive is commanded to retract the shimming wedges back a given distance. Typically, the shim gap changes from cycle to cycle. Thus, the settings will vary from cycle to cycle and this is to assure consistency in results as explained above. The form and cure process thereafter continues with this shimming process having taken only a matter of seconds.

[0012] A full understanding of the invention can be gained from the following description of the preferred embodiment when read in conjunction with the accompanying drawings in which:

[0013] Figure 1 is a front elevation of the prior art form and cure press assembly.

[0014] Figure 2 is a front elevation of the form and cure press including the shimming device of the present invention.

[0015] Figure 3 is an isometric drawing of the automated shimming device of the present invention shown between the cure mold and the pressing plate.

[0016] Figure 4 is a schematic cross section of a wedge set of the shimming device of the present invention.

[0017] Figure 5 is a schematic elevation of one line of wedge sets and servo drive members of the shimming device of the present invention.

[0018] Figure 6 is a partial elevation of one end of the wedge sets and one of the servo drives of the present invention.

[0019] Figure 7 is a flow chart of the microcomputer control system of the present invention.

[0020] For convenience of disclosure, the present invention is described in the context of a form and cure press for making superconducting coils, however, it should be understood that the device and method of the present invention have many other applications in forming and curing materials other than superconducting coils.

[0021] Referring now to Figure 1, a conventional form and cure press will be described in further detail. The upper press structure, generally designated as 24, has alignment shaft 25 enclosed therein. Alignment shaft 25 passes through an opening in cure mold 26. A keystone-shaped member 27 is affixed at the end of alignment shaft 25. Lower pressing plate 28 supports winding mandrel 29 and pressing bars 30 and 31. Between pressing bar 30 and one side of keystone-shaped member 27 is one coil arc 32. A second coil arc 33 is placed between pressing bar 31 and the opposite side of keystone-shaped member 27. When the form and cure press is in the press position a small gap 34 exists between one side of the base of cure mold 26 and pressing plate 28; a second gap 35 exists between the opposite side of the base of cure mold 26 and pressing plate 28. The manual shimming process described above is used to close gaps 34 and 35. Instead of the labor intensive shimming process described above, the device of the present invention can be used to close gaps 34 and 35.

[0022] Referring now to Figure 2, the shimming device of the present invention will be described in further detail. Curing mold 36 has a generally arc-shaped inner curing area 37. The overall width of the curing mold 36, designated by reference character 38, is about 10 inches in a typical form and cure press used to manufacture superconducting coils. The height of cure mold 36, designated by reference character 39, is typically about 7.25 inches. The cure mold 36 forms the upper mating structure of the form and cure press.

[0023] The lower mating structure is comprised of winding mandrel 41 which has attached thereto a set of upstanding pressing bars 43 and 45. An arc of coil material 47 and an arc of coil material 49 are loaded into the assembly above pressing bars 43 and 45, respectively. The coil arcs 47 and 49 are held in place and compressed at ends 51 and 53, respectively, by keystone-shaped member 55. The lower end 57 of coil arc 47 is acted upon and compressed by pressing bar 43. The lower end 59 of coil arc 49 is acted upon and compressed by pressing bar 45.

[0024] A shimming device 65 is placed between the base of cure mold 36 and pressing plate 66. A second shimming device 67 is placed between the opposite side of the base of cure mold 36 and pressing plate 66. The shimming devices 65 and 67 act directly on the base of cure mold 36, however, the position of the mold 36 relates to the amount of compression and pressure applied to the coil material during the curing process and in turn the amount of thermal expansion allowed between, for example, coil arc 47 and pressing bar 43 during the form and cure process.

[0025] The wedge sets of the shimming device of the present invention are shown in assembled form in Figure 3. The upper structure of the form and cure press is generally designated as 68. Upper structure 68 controls cure mold 36. The lower structure of the form and cure press is generally designated by reference character 69. Lower structure 69 supports and controls the movement of pressing plate 66. A first set of wedge members 70, described in further detail below, are assembled on to one side of press plate 66 between press plate 66 and cure mold 36. another set of wedge members 72 are placed between an opposite side of cure mold 36 and press plate 66.

[0026] The wedge sets of the shimming device of the present invention will be discussed in further detail with reference to Figure 4. Upper wedge member 71 has a flat upper surface 73, a wide end 75 and a narrow end 77. Narrow end 77 contacts contiguous upper wedge member 79 at its wide end 81. Upper wedge member 71 has a lower surface 83 which is an inclined plane.

[0027] Lower wedge 85 has a flat bottom 87 which is supported by a base plate 89 on the lower press plate of the form and cure press. Base plate 89 is preferably comprised of tool steel which rests on a thermal barrier 90 which may be a fiber glass insulating material. Lower wedge member 85 also has wide end 91 which abuts contiguous lower wedge member 93. The upper surface 95 of lower wedge member 85 is an inclined plane which slidingly engages inclined plane surface 83 of upper wedge member 71. In the preferred embodiment, the slope of inclined plane surface 83 is 10 to 1 meaning that ten increments of motion by lower wedge member 85 in the horizontal direction will result in one increment of distance travelled in the vertical direction by upper wedge member 71.

[0028] The dimensions of the wedges of the exemplary embodiment based upon a typical system containing sixty wedge sets for each side of the cure mold, are a length (designated by reference character 97) of about 25.4 cm (10 in), a height at wide end 75 (designated by reference character 99) of about 4.32 cm (1.70 in), and a height at the narrow end 77 of about 1.78 (0.7 in). The width, (not visible in Figure 3) is designated by reference character 101 in Figure 2 and it is about 6.27 cm (2.47 in). As will be understood from these dimensions the wedge sets are very narrow yet they must withstand a large amount of pressure.

[0029] The wedges are preferably mounted in a slot-and-pin fashion. Referring still to Figure 4, a vertical slot 103 is located generally towards wide end 75 of upper wedge 71. Pin 105 is contained within slot 103. Pin 105 restricts horizontal motion of wedge 71 and also serves to facilitate smooth vertical motion of the wedge 71. Pin 105 is received into side members 108 and 110 (Figure 2), and held there by any suitable means such as by a true arc snap ring.

[0030] Lower wedge 85 preferably has horizontal slot 107 containing pin 109 (Figure 4). This slot and pin arrangement primarily serves to lock lower wedge member 85 in proper alignment with other lower wedge members while facilitating the desired horizontal motion. Pin 109 is received into a suitable opening in side members 111 and 112 shown in Figure 2.

[0031] Referring to Figures 5 and 6, the drive mechanism for moving the wedge sets will be described. In a typical system, a dc servo drive 113, preferably having a ball-and-moving-screw type linear activator 115 associated therewith, is disposed generally at one end 117 of the system (Figure 5). In the exemplary embodiment drive 113 is the UP drive. The DOWN drive 119 is located at the other end 121 of the system. DOWN drive 119 also has linear activator 123 associated therewith.

[0032] Linear activator 115 which is associated with UP drive 113 has drive arm 125 which may be a moving screw which acts on lower wedge 127. Lower wedge 127 has drive bar 129 which is engaged by drive arm 125 when arm 125 is extended upon command by the servo drive 113. When an up motion is desired, drive 113 communicates with linear activator 115 to extend drive arm 125 to thereby move lower wedge 127 laterally towards the next contiguous wedge 130 which in turn moves the next wedge and each wedge in the system follows. The inclined planes of the lower wedges slide along the inclined planes of the upper wedges and this causes an overall upward motion in the entire assembly of wedge sets. In the meantime, the drive arm 131 of DOWN drive 119 retracts back as the wedges move toward it to allow the motion initiated by UP drive 113.

[0033] Similarly, a downward motion of the entire assembly is effected when DOWN drive 119 commands linear activator 123 to move its drive arm 131 towards lower wedge 133. Lower wedge 133 may have a drive bar 135 formed thereon which is acted upon by drive arm 131 to urge lower wedge 133 and, thus, contiguous lower wedge 137, in a lateral direction opposite to the direction referred to above. Each lower wedge similarly communicates motion to the next contiguous wedge member. The inclined planes of the lower wedge members move towards the left in Figure 5. As a result the corresponding inclined planes of the upper wedges which are restrained from any horizontal motion by associated pin and slot arrangements, slidingly move downwards resulting in an overall lowering of the wedge assembly. On detection of this motion in the opposite direction, UP drive 113 releases the drive arm 125 such that lateral motion in the DOWN direction is allowed.

[0034] Referring now to Figure 6, a linear activator 141 is driven by servo drive 139. Rotary motion is communicated from servo drive 139 about pin 143 of linear activator 141. This rotary motion is then translated by linear activator 141 into linear motion which is then transmitted by drive arm 145 to narrow end 146 of wedge 147.

[0035] The initial rotary motion is controlled by a microcomputer 148 (Figure 5) suitably programmed in a manner which will be understood with reference to the flow chart of Figure 7. It is initially determined, as shown in block 151, whether the appropriate point in the form and cure process has been reached. This is typically when the coil material is loaded into the system and the lower mating tool comprising the winding mandrel and pressing bars are brought in contact with the arc-shaped coil winding in the interior of the mold (Figure 2). The temperature and pressure are then raised to the desired levels and this is confirmed in step 153. The motion of the overall press as well as the temperature and pressure is controlled by the main control system of the overall assembly. If these conditions are met, the UP drive is commanded by the microcomputer to move as indicated by step 155. The wedge sets are moved into contact with the cure mold as indicated by step 157.

[0036] When contact is detected by an associated position sensor or other suitable device which will be readily understood by those skilled in the art, then the UP drive is commanded to cease upward motion as indicated in step 159. The distance travelled by the wedges to arrive at the point of contact is then calculated as in step 161. This calculated distance is entered into the computer 148 which is programmed to calculate the final shim setting using a predeterminal formula as shown in step 163. An optimum shim setting based upon this calculation is retrieved as indicated by step 165. The predetermined formula relates to coil material used, desired tolerances, temperatures, pressures and other operating conditions as would be understood by one skilled in the art. As indicated by step 167, the DOWN drive is then commanded to retract the wedge sets back to the appropriate setting as determined from the historical data. This process takes about 30 seconds. The main control system of the form and cure process then continues, and the temperature is increased to typically about 150°C and the pressure is increased to about 15,000 psi on the coil arc. These parameters are held for a desired time interval. A cool down routine is then performed and the coil arcs are thereafter removed from the press.

[0037] In accordance with the method of the present invention, the press mold 36 (Figure 2) is raised. The coil material 47, 49 is loaded between keystone-shaped member 55 and pressing bars 43 and 45, respectively. The mandrel 41 is then raised into contact with the upper curing mold 36. The entire pressing assembly is heated to an initial temperature of 90°C and the press tonnage is increased to an initial pressure which is preferably about 1,500 psi on the coil arc. The wedging systems 65 and 67 are then activated and the UP drive 113 (Figure 5) acts on the lower wedge member 127 to raise the upper wedges into contact with the base of the cure mold 36. The computer verifies the distance traveled by the wedge sets. An optimum shim setting is then calculated. The wedge systems are then drawn back a given distance to conform to the computer generated optimum distance. This setting is maintained and the temperature is raised to a predetermined curing temperature of about 150°C. Press tonnage is raised to about 15,000 psi. These conditions are held for a time period adequate for curing to take place. A cool down cycle is then performed. The wedging systems are retracted and the press is thereafter opened and the coil material is then removed.

[0038] It should be appreciated that the present invention provides an automated shimming system which conveniently and expeditiously assures that dimensional tolerances are consistently achieved in the manufacture of superconducting coils. The method and apparatus represents a savings of hours in process time. Additionally, labor costs are saved.

Claims

1. An adjustable cure press closure assembly characterized by movable shim means (70, 72) comprised of a plurality of contiguous sets of wedge members (71, 85), each said set (71, 85) being composed of an upper wedge member (71) and a lower wedge member (85), said upper wedge member (71) having an inclined plane bottom surface (83) which slidingly engages a corresponding inclined plane top surface (95) of said lower wedge member (85), and motion of a first wedge member results in motion of a next contiguous first wedge member and the inclined plane of each said first wedge member slidingly engages the inclined plane of a second wedge member of that set whereby an overall upward or downward adjustment of said cure press closure assembly is achieved and said movable shim means also having means restricting said second wedge members to vertical motion.

2. The adjustable cure press closure assembly of Claim 1 further characterized by means for driving (113, 119) said movable shim means having means for urging (125) said first wedge member in a first horizontal direction, and a second means (131) for urging an opposite first wedge member in an opposite horizontal direction.

3. The adjustable cure press closure assembly of Claim 2 wherein means restricting said second lower wedge members to vertical motion comprises a vertically extending slot in each said second wedge member and a substantially rigid pin engaged in each said slot (103, 105).

4. The adjustable cure press closure assembly of Claim 2, further characterized by a microcomputer (148) operatively associated with said drive means (113, 119) programmed to control said upward and downward motion of said movable shim means (70, 72) by controlling activation of said means for urging (125) said first wedge members in said first horizontal direction and said opposite horizontal direction.

5. The adjustable cure press closure assembly of Claim 4 wherein said microcomputer (148) is also programmed to determine an optimum position for said movable shim means.

6. The adjustable cure press closure assembly of Claim 2 wherein said means for driving (113, 119) said movable shim means comprises an UP drive means (113) having a servo drive means (113) positioned at one end of said movable shim means with a linear activator arm (115, 125) operatively associated with a first wedge member (127) at said one end of said movable shim means which urges said first wedge member (127) in a horizontal direction which in turn causes each of said first wedge members to impart motion to its next contiguous wedge member, whereby an overall upward motion of said closure assembly is achieved and a DOWN drive means (119) having a servo drive means (119) positioned at an opposite end of said movable shim means with a linear activator arm (123, 131) operatively associated with an opposite first wedge member (133) at said opposite end of said movable shim means which urges said opposite first wedge member in an opposite horizontal direction which in turn causes each of said opposite first wedge members (133) to impart motion to its next contiguous wedge member (137), whereby an overall downward motion of said closure assembly is achieved.

7. The adjustable cure press closure assembly of Claim 6 wherein said first wedge members (85) are the lower wedge members of the movable shim means (70, 72), and the second wedge members are the upper wedge members (71) of the movable shim means (70, 72).

8. An adjustable cure press closure assembly for a pressure form and curing press for producing coil arcs (47, 49), said pressure form and curing press having a cure mold (36) having a semi-circular cross section (37) for contacting coil material (47, 49), a mating mandrel (41) received between two up-acting elongated pressing bars (43, 45) mounted on an up acting press plate (66) which initiates motion of said mating mandrel (41) and pressing bars (43, 45) towards said mold (36) to press said coil material (47, 49) into said mold (36) at a predetermined pressure, and a cure press closure assembly being characterized by movable shim means (65, 67) composed of a first line of contiguous wedge sets (70) placed between said up-acting press plate (66) and one side of a base of said cure mold (36), a second line of contiguous wedge sets (72) placed between said upacting press plate (66) and the opposite side of said base of said mold (36), each said wedge set being composed of a lower wedge member (85) having an inclined plane top surface, said inclined plane top surface (95) of said lower wedge member (85) slidingly engaging an inclined plane (83) of an upper wedge member (71) such that horizontal motion of said lower wedge member (85) results in vertical motion of said upper wedge member (71), and said contiguous wedge sets being positioned in line with one another such that horizontal motion of each lower wedge member (85) imparts horizontal motion to its next contiguous lower wedge member (85) whereby an overall upward or downward motion of that line of said contiguous wedge sets of said movable shim means (70, 72) is achieved; servo drive means associated with each said line of contiguous wedge members, each said servo drive means (113) comprising a first servo drive member (113) having a linear activator arm (125) operatively associated with a lower wedge member (127) at one end of said line of contiguous wedge members and a second servo drive member (119) having a linear activator arm (131) operatively associated with a lower wedge member (133) at the other end of said line of contiguous wedge members, whereby motion of said linear activator arm (125) of said first servo drive member (113) results in overall upward motion of said line of contiguous wedge members and motion of said linear activator arm (131) of said second servo drive member (119) results in overall downward motion of said line of contiguous wedge members; and means to control said servo drive means.

9. The adjustable cure press closure assembly of Claim 8 wherein said means to control said servo drive means is a microcomputer (148) programmed to command said linear activator arms (125) of said first servo drive members (113) of each said servo drive means to urge said wedge sets upwards in contact with the base of said cure mold (36), and to calculate said distance travelled by said upward motion, and to command said linear activator arm (125) of said servo drive means to urge said wedge sets out of said contact and to retrieve stored information related to said calculated distance travelled, and to readjust said upward motion of said wedge sets according to a predetermined stored value based upon said information retrieved.

10. A method of forming and curing a superconducting coil, said method characterized by the steps of:
   providing a press mold (36) having a semi-cylindrical internal mold shape (37) to form coil arcs (47, 49), and an upwardly acting press plate (66), and an automated shimming device (70, 72), and an associated microcomputer (148), preparing said press mold (36) to predetermined initial conditions, raising said shimming device (70, 72) from an initial starting position to close a gap between said press mold (36) and said press plate (66), measuring the distance travelled when said shimming device is raised to close said gap, calculating a final closure position of said shimming device based upon a predetermined formula, retracting said shimming device (70, 72) from said initial starting position to a final closure position, placing said cure mold (36) at predetermined curing conditions, and forming and curing said coils (47, 49) in said mold.

11. The method of Claim 10 including preparing said press mold (36) by loading coil material (47, 49) into said mold and raising mold temperature to an initial temperature of about 90°C, and raising pressure of said mold to about 1,500 psi, on said coil arcs.

12. The method of Claim 11 including placing said cure mold (36) at predetermined curing conditions by raising said mold temperature to a curing temperature of about 150°C, raising press pressure to about 15,000 psi holding said final closure position of said shimming device (70, 72) for a predetermined time interval, performing a predetermined cool-down cycle, retracting said shimming device and unloading said coil material.

Drawing