US2675581A

US2675581A - Apparatus for producing insulated resistor shells

Info

Publication number: US2675581A
Application number: US241595A
Authority: US
Inventors: William M Payne
Original assignee: Speer Carbon Co
Current assignee: Speer Carbon Co
Priority date: 1951-08-13
Filing date: 1951-08-13
Publication date: 1954-04-20
Anticipated expiration: 1971-04-20

Description

April 20, 1954 w. M. PAYNE APPARATUS FOR PRODUCING INSULATED RESISTOR SHELLS Filed Aug. 13, 1951 2 Sheets-Sheet l l a I II.

R m m m WILL/AM M. PAYNE ATTORNEYS.

2 Sheets-Sheet FIG. 30

u v 3 6 I F INVENTOR. WILL/AM M. PAYNE ATTORNEYS Ap 1954 w. M. PAYNE APPARATUS FOR PRODUCING INSULATED RESISTOR SHELLS Filed Aug. 13, 1951 FIG. 3B

FIG. 35.

Patented Apr. 20, 1954 2,655,581 APPARATUS ms.monueifiemsemrss" LLS Meet ii searsmear;-=' 4 Clairfii (CL 18;?

This: mvemen' relatesi to apparatus "fqrj rd diicing insulated shells "for molded re ister I Asi' described in I-Ie'rri cl "arid" Veley Patent 2,454,508; dated November 23," 1948; insulated molded resistors may be formed by a step-by steplpi'o'cedure which involves first'the formation of a' shell by compactingpf insulatin moldiing powder followedi bytpr'ov'iding in said" shellu'e sistor'leads and resistance material in the forn i of a compacted powder having suitable conue ivity W1 in PaLiQ T Th Q 16 o me assemblies thus provided are baked to produce the final insulated resistors. As pointed out' in, said patent, the resistors-may be provided in large numbers in I a single sequence of operations bythe use of multiple cavitymolding' devices as illustrated in said patent. v

The general object of the present invention is; the provision of mechanism for producing the insulating shells in the form of'preforms of com pacted molding powder, theshells being located in the cavities of a plate for the subsequent formation of the complete resistors.

Heretofore such shells have been formed through the use of various elements bymanual operations, the elements being suitably located relatively to each other by spacers-or 'the like" with pressure applied at proper times 'bynieans In accordance with'-- the of a suitable press. present invention, a press is provided which has movable elements carrying various elei'nent'sin'' volved in the shell formation with the"pr'ovision of various pressure cylinders for securing proper movements and for properly positioning 'theele ments in the various -stagesof shell formationj' The present invention leads not only tohigh" speed formation of the shells but a'high' degree of uniformity which is'of 'importance'in securing uniformity of the final resistance values."

The general objects of the invention just indicated as well as'other objects particularly re-' lating to details of construction'and operationwill become apparent from the'following description read in conjunction with the accompanyingdrawings, in which: v

Figure l is an elevationgpartly broken away and partly in section showing ,a preferred forrn Figs: 3A 1 to 3G: inclusive; are

indicated at j4 whicn'at their up er endsfsu'ppo'rt nsuring operation tithe press? 'rhenie el her 8 ma of ope ngs; and in "particular when mall 'wam age resis'toi' shells arei fprfodu'ced' may con sequently" lea-dfto the simultaneous of a 'quift'e large umber of'shells. Extending I2 connected 'at' their-"upper 'jen'ds' 'by' a mem er l4." slidineon'th'e osts" l2 there is apl'aten; "5 which is arrangedto be raised and lowered throue h connection to 'th'e plunger [8 movable in ahydraulically operatedbylinde'r 2 0'1 A bra'cket" 22 carried by the platen pe na ts a'series of l s 2 1', 'one'f or' each of'the cavities nimaeew ID and adap s 42 1 m; e ts jthe Pant s. 9 slidab'le on posts 12 is a secondplaten'ze in' the form o f a yoke which is arrangedto,'be raised and lowered ibylplunge rs 28 actuated hydraue lic'cylinders 30, bracket members is a filler plate 3| provided with cylindrical openings oi the same diameter as-the cavities ll] 1andi'aligned therewith. As will appear hereafterthisfillerplate 3i is provided 'for thepurpose'of receiving'and retaining" powder which "is displaced upwardly by plungers entering" the cavities I05 The downward movement of platen 26 with respect'to the yoke 6 is limited by'space'r'members 32in the-form "ofmetahblocks *which" provide adowernlost positionjlof fillefplateSl substantially in contact with the uppe'r'surface of the member '8.' Adjustable stop member's'iifcarried by the plateri 'I 6 limit the'do'wnward movement of plat'en"l6 with respect 'toplat'en 2e"'and,con-

seduently, with respect-to yoke"6;' Thus there" as secured adfinite'lowermost' position of the" tubes 24 within the upper ends of the cavities" Ill.

Anothrplaten 36 is sl'idably mounted'on the posts I'andfis arranged'to bemov'ed upwardly and downwardly by the plunger 38 which'enters the hydraulic cylinder 40. As will appear hereafter ,mo ments (of th'i'sfplaten are controlled by a h aulic servo mechanisms for "securiifg' c'cu are. v 3' fP Qihi memb w f the ions of this member are critical forthe p H g 1 the press "comprises a "base 2 to which aresecured' four upright posts y be' provided with any desired number formation Securedtofthis fplaten by side ports through upright rods 42 a plate 44 on which is secured a plate 46 carrying tubular plungers 48 which are arranged to enter the cavities l6.

Another platen 56 is mounted to slide on the posts 42 and is arranged to have upward and downward movements imparted thereto by plungers 52 operated from hydraulic cylinders 54. A plate 56 carried by platen 50 mounts upright pins 58 which are arranged during operation to pass through the tubes 48 and cavities [6 into the upper tubes 24. Adjustable stop members 69 are provided to adjust the limit of approach of platen 50 to platen 36. It may be here noted that whereas the other hydraulic cylinders are fixed to fixed parts of the press, the cylinders '54 are carried by the platen 36.

The servo mechanism for controlling the platen I 36 is illustrated particularly in Figure 2. This comprises a servo valve indicated at 62 which is of known type rovided with a pair of slide valves in the form of concentric cylindrical members arranged to receive oil under pressure and deliver it to the cylinder 46. The respective valve mem bers are secured to externally projecting

rods

64 and 66, the former being provided with a roller 68 engageable by the cam"!!! of a cam lever H pivoted at 72 and subject to manual positioning.

The lever ll is provided with a latch 74 which cooperates with

notches

16 and 18 in adjustably positionable members to provide in particular two definitely located positions of the lever and hence of plunger 64. In addition lever H may be moved to an extreme position which, as will appear, corresponds to full withdrawal'of the platen 36.

The rod 66 is connected through a link 86 to an arm 82 carried by a shaft 84 which is provided with a second horizontally extending arm 86 connected by link 88 to a pin 96 carried by the platen 3S.

' The servo mechanism thus provided insures a definite position of the platen 36 for each adjusted position of the cam lever 1| The position of the platen may thus be determined to a very high degree of accuracy, the platen being moved with great force by hydraulic pressure to the various desired positions. v

The platen 36 alone need be positioned with accuracy independently of any stop members associated therewith. The other platens are merely moved between extreme positions determined on the one hand by limits of movements of their plungers and on the other hand by the stop members such as 32, 34 and 60. There is of course provided a high pressure oil supply of conventional type which is not illustrated.

The sequential operations of the various elements may be best described with reference to the successive Figures 3A to 3G, inclusive, which show the relative positions of the parts in particular association with the cavity member 8. In these figures, only one cavity 18 and the parts associated therewith are illustrated, but it will be understood that simultaneously with the events I occurring in connection with one cavity similar events occur in connection with all of the other cavities to produce simultaneously a large number of shells. v

Referring first to Figure 3A, the platen 36 is raised to its uppermost position defined by the stop member 16. As will appear hereafter this is its compression position in which the upper ends of the tubular plungers 48 are located well within the lower ends of the cavities !6. At this same time the platen 56 is in its lowermost position defined relative to the platen 36 by the stop members 60, the pins 58 thenbeing located sub:

4 stantially in coincidence with the upper ends of the tubular plungers 48. At this time the platens l B and 26 are both raised to clear the upper surface of the mold member 8.

With the parts thus positioned the operator will pour on the upper surface of plate 8 the molding powder which is distributed about by a scraper so that the powder will fill each of the cavities l0 flush with the upper surface of mold plate 8 as indicated at P in Figure 3A. Excess powder is then brushed off. Inasmuch as the tubular plungers 48 and pins 58 then occupy a definite position in the cavities, it will be evident that a definite amount of powder in relatively loose condition will thus be located in each cavity.

Through the operation of a suitable control valve (not shown) the platen 26 is then moved downwardly to a. position limited by the stop members 32 with the result that the filler plate 3| is positioned substantially in contact with the upper surface of the mold plate 8. The result is the condition indicated in Figure 3B in which the openings in the filler plate 31 align with and serve to form upper continuations of the cavities H).

The lever 1| is now moved to position the latch 14 in notch 18 resulting in a slight downward movement of platen 36 which is followed by platen 5D. The result is that the tubular plungers 48 and pins 58 are correspondingly lowered to the position illustrated in Figure 3C.

The next operation involves the manipulation of a valve (not shown) serving to move upwardly the platen 50 to carry the pins 58 to the position illustrated in Figure 3D in which each pin is projected upwardly through its corresponding cavity In and into or through the corresponding opening in the filler plate 3!. The purpose of the provision of the filler plate will now be evident, sufiicient of the powder being displaced by the pin from each cavity to enter the corresponding opening in the filler plate. The filler plate prevents overflow as indicated in Figure 3D.

The next event is illustrated in Figure 3E. Platen I6 is lowered by manipulation of a valve (not shown) to bring the tubular plungers 24 downwardly through the openings in the filler plate and into the upper ends of the cavities ll). The extent of movement is limited by the stops 34. A partial compression of the molding powder then takes place locating the powder as indicated at P in Figure 3E. However, the motion thus provided is not sufficient to insure accurate final compression of the molding powder and consequently in the next step of operation the lever II is returned so that latch 74 enters notch 16 producing an upward movement of platen 36 which will position the tubular plungers 48 in the same position as illustrated in Figure 3A. The result is the condition illustrated in Figure 3F in which the powder is now fully and accurately compressed to provide the preformed shell indicated at S.

In the next operation the various movable elements are withdrawn to the position illus trated in Figure 3G, the pins 53 being first pulled downwardly by lowering movement imparted to platen 50 which is moved to its lowermost position with respect to platen 36 as determined by stops 60. This serves to pull the pins from the preforms without disturbing their positions. The platen 36 is then fully withdrawn by movement of lever H to its'extreme forward position and'platens I6 and 26 are raised to the original that the mold plate 8 is freed to be horizontally removed from the press, for replacement by an empty plate.

The plate 8 containing the shell preforms is then subjected to further operations as described in detail in said Herrick and Veley patent, there being located in the shells the resistance powder and headed leads, the entire assembly being compressed with final ejection of the resistor assemblies thus resulting. These assemblies are then subject to baking to form the final resistors.

While a preferred sequence of operations has been described it will be evident that variations in the steps may be used to achieve the same general ends. For example, the filling plate 3! may be omitted in the event that it is desired to use a molding plate 8 of such thickness compared to the ultimate lengths of the shells that the lower tubular plungers and pins may be saidciently withdrawn after initial filling of the cavities that when the pins are projected upwardly there will be sufficient cavity space to prevent overflow of the powder from the upper ends of the cavities. It will also be evident that with the application of sufficient pressure from the plungers 2d the final compression may be achieved at the stage indicated in Figure 3E.

The apparatus described is flexible and adjust ments may be readily made to provide resistor shells of various lengths and diameters. stops 34 and 60 may be adjusted and the stop members 32 may be replaced by others of different size. Furthermore the members '16 and 18 which determine positions of the levers "H may be adjusted to secure the desired limits of motion.

It will be understood that the invention is susceptible to variations such as indicated and, accordingly, is not to be construed as limited except as required by the following claims.

What is claimed is:

1. Apparatus for the formation of shell preforms for molded insulated resistors comprising a fixed member for holding a plate having a plurality of upright cylindrical cavities therein, a pair of platens movable relatively to said fixed member and supporting upper and lower tubular plungers arranged to enter said cavities, a third platen movable relatively to said fixed member and supporting pins arranged to enter said tubular plungers and said cavities, a fourth platen movable relatively to said fixed member and sup porting a plate having openings adapted to provide upward continuations of said cavities, and means for effecting relative movements of said platens with respect to each other and said fixed member.

2. Apparatus for the formation of shell preforms for molded insulated resistors comprising a fixed member for holding a plate having a plurality of upright cylindrical cavities therein, a pair of platens movable relatively to said fixed member and supporting upper and lower tubular The plungers arranged to enter said cavities, a third platen movable relatively to said fixed member and supporting pins arranged to enter said tubular plungers and said cavities, a fourth platen movable relatively to said fixed member and supporting a plate having openings adapted to provide upward continuations of said cavities, and means for effecting relative movements of said platens with respect to each other and said fixed member, the means for moving said third platen being carried by the platen supporting the lower tubular plungers.

3. Apparatus for the formation of shell preforms for molded insulated resistors comprising a member having a plurality of upright cylindrical cavities therein, means providing an accurately predetermined depth of said cavities while a charge of molding powder is supplied thereto, means for increasing the depth of said cavities after the powder charge is supplied thereto, means raising a centrally disposed pin upwardly through said cavities and the powder therein, and means for compressing the powder within the cavities and surrounding the pins.

4. Apparatus for the formation of shell preforms for molded insulated resistors comprising a fixed member for holding a plate having a plurality of upright cylindrical cavities therein, a first platen movable relatively to said fixed member and supporting upper tubular plungers, a second platen movable relatively to said fixed member and supporting lower tubular plungers, said upper and lower tubular plungers being arranged to enter said cavities, a third platen movable relatively to said fixed member and supporting pins arranged to enter said tubular plungers and said cavities, a fourth platen movable relatively to said fixed member and supporting a plate having openings adapted to provide upward continuations of said cavities, means for effecting relative movements of said platens with respect to each other and said fixed member, means for limiting the approach of said first platen to said fourth platen, means for limiting the approach of said second platen in its upward travel to said fixed member, for limiting the downward travel of said second platen and for establishing an intermediate position of said second platen between the limits of its upward and downward travel, and means for limiting the upward and downward travel of said third platen with respect to said second platen.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 813,209 Holmes Feb. 20, 1906 1,143,034 Brown June 15, 1915 1,839,056 Short Dec. 29, 1931 1,904,864 Jongedyk Apr. 18, 1933 2,127,994 Davis et al Aug. 23, 1938 2,398,227 Hubbert Apr. 9, 1946