US2916771A

US2916771A - Pressing tools particularly for the manufacture of large-area pressings

Info

Publication number: US2916771A
Application number: US547231A
Authority: US
Inventors: Lang Kurt; Ladewig Wilhelm; Hans Fritz; Reichelt Werner; Klauss Erich; Schadlich Alfred
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-11-16
Filing date: 1955-11-16
Publication date: 1959-12-15
Anticipated expiration: 1976-12-15

Description

Dec. 15, 1959 K. LANG ETAL 2,916,771

PRESSING TOOLS PARTICULARLY FOR THE MANUFACTURE OF LARGE-AREA PRESSINGS 3 Sheets-Sheet 1 Filed NOV. 16, 1955 3 Sheets-Sheet 2 LANG ET AL PRESSING TOOLS PARTICULARLY FOR THE MANUFACTURE OF LARGE-AREA PRESSINGS Dec. 15, 1959 Filed Nov. 16, 1955 United States PatentO lice PRESSING TOOLS PARTICULARLY FOR THE MAN UFACTURE OF LARGE-AREA PRESSINGS Kurt Lang, Wolfgang Barthel, Wilhelm Ladewig, Fritz Hans, and Werner Reichelt, Zwickau, Erich Klauss, Mose], near Zwickau, and Alfred Schiidlich, Zwickau, Germany The present invention relates to press molding machines, and more particularly to pressing tools forming part thereof which are capable of being heated and cooled for the manufacture of predominantly large-area pressings consisting preferably of synthetic materials.

It is known in the art to provide thick-walled steel tools for the pressing of large-area pressings. In these tools pressures of 250-400kilograms per square centimeter are applied, the material flowing only at such high pressures. However, thick-walled tools cannot be applied to pressings which are to be cooled after the pressing operation because the required cooling after each pressing takes too much time and thus is uneconomical.

It is an object of the present invention to provide a pressing tool adapted to press large-area parts to be cooled after the pressing operation.

It is another object of the present invention to equalize any differences, in the accumulation of the material in the body to be pressed. I

According to one embodiment of the present invention large-area pressings to be cooled after the pressing operation are manufactured by means of pressing tools in which a heat insulating layer is arranged on the base memberiof the lower portion of the tool, andfa shellshaped mold provided with'heating channels is arranged on the heat insulating layer whereas the upper part of the tool is provided with a rubber pad traversed prefer- 2,916,771 -Pa t ented Dec. 15, 1959 2, v a part of a pressing tool according to the present invention, r t

Fig. 7 is asectional part elevation on an enlarged scale of another embodiment of the present invention,

Fig. 8 is a sectional elevation of a further embodimentv of the present invention,

Fig. 9 is a sectionalelevation on an enlarged scale of part of the embodiment shown in Fig. 8,

Fig. 10 is a part section of still another embodiment of'the present invention,

Fig. 11 is a sectional elevation of a still further embodiment of the present invention,

Fig. '12 is a sectional elevation on an enlarged scale along the line AB shown in Fig. 13, t

Fig. 13 is a plan view of some parts shown in Fig. 12, and

Fig. 14 is a sectional elevation of part of a pressing tool incorporating the parts shown in Figs. 12 and 13.

Referring now to the drawings in detail and first to Fig. .1, a base member 3 is provided with a bowl shaped recess 1. An insulating layer 6 consisting of a material being a poor conductor of heat is arranged in the recess 1, the layer 6 being-rigidly connected to the base member 3 by suitable means 7. The heat insulating layer 6 is subdivided by separating fillets or bars 10 into square panels having dimensions of about 200 millimeters X 200 ably by heating tubes and being attached to the countermember or press ram by means of an interposed heat insulating layer.

The rubber pad is intended to equalize any diflierences in the accumulation of materials of'the preliminary body to be pressed, and any changes of the pressing 'gap caused by heat expansion ofithe material. Without this rubber pad it is impossible to press the preliminary material'in a perfectly uniform manner at low pressures amounting approximately to 40 kilograms per square centimeter. This holds particularly for parts to be subjected to a high degree of deformation.

The baseymember for the lower portion of the tool as well as for therubber pad consists perferably of cast iron, compact timber, steel'with magnesite, the material known under the trade name Igurit, concrete, or similar materials.

Other objects and advantages of the present invention will become apparent from the following detailed description thereof in connection with the accompanying drawings showing, byway offexample, some embodiments of a pressing tool according to the present invention. In the drawings p p Fig. 1 is a sectional elevation of part of a pressing tool for parts capable of an easy deformation,

Figs. 24 illustrate several embodiments of fastening means for a rubber pad forming part of the pressing tool shown in Fig. 1, e p t Fig. 5 is a sectional elevation onan enlarged scale of part of the pressing mold shown in Fig. 1,

Fig. 6 is a sectional elevation of a swage for making millimeters. A thin foil 19 consisting preferably of rolled lead is arranged on the insulating layer 6. 'A 'shellshaped mold 14 preferably consisting of neatly machined steel is provided on the lower side thereof with a plurality of heating channels 2. t

As shown in Fig. 5, the heating channels 2 are covered bytcover sheets 4co nsisting preferably of metal which are separated from each other by filling strips or hands 5 in order to obtain a smooth contact and sliding surface. Themetal sheets 4 and filling strips.5 are welded by welding joints 5:; to the shell-shaped mold 14, the upper side of which-corresponds to the shape of the article (not shown) to be pressed from a synthetic material by the pressing tool. I V p The prepressed material (not shown) is pressed into the shell-shaped mold 14 by means -of a rubber pad 11 consis'ting of a synthetic rubber of medium hardness, or a similar-heat resistant rubber mixture. The rubber pad 11 is surrounded by'a strong frame 12 "and vulcanized with the rim portion thereof to the latter. However, if desiredthe rubber pad 11 may'befastened to the frame 12 by screw bolts 16 cooperatingwith countermembers 17 such as nuts and sleeves 18 arranged on the screw "bolts 16 between the frame 12 and the countermember 17. This kind of connection facilitates and accelerates the exchange of the rubber pad 11.

A system of heating pipes 13is arranged in the rubber pad 11 near the" upper side thereof. An insulating layer 9 consisting of a material being a poor conductor of heat is arranged above therubber pad 11. A countermember or pressing ram 8 is arranged above the insulating'layer '9 which is subdivided by Z-shaped brackets 15 fastened by screw bolts such as 1511 to the pressing ram 8. I The 'Z-shaped parts 15 extend through the insulating layer 9 and form the cover of the recesses 13a provided in the rubber pad 11 accommodating the heating pipes 13. TheZ-shaped parts 15 carry the rubber pad 11 by means of parts such as stirrups 33 and anchoring members 32 vulcanized into the rubber pad 11. The insulating layer 9 is subdivided into small fields by partitions 10 similar to the insulating fillets or bars 10 arranged in the heat insulating layer 6. The" mold 14 is connected with the rim thereof by a connectingmember 20a arranged at the rim portion of the heat insulating layer 6, to a centering 3 member connected'to' the base member 3 by screws such as 20b.

The operation of this device is as follows:

If an article is to be pressed by the pressing tool described her'einabove the pr'e'ssingram 8, the" insulating layer 9 and the rubber pad 11 are lifted from the'position shown in} Fig. 1 by drivingmeans (not shown). A heating fluid such as steam is admitted to the heating channels 2 and pipes 13 so as to heat thoroughly the shell-shaped mold 14 and the rubber pad 11; After the same are sufficiently heated, the material to be pressed, preferably a synthetic materiahis inserted between the shell-shaped mold 14 and the rubber pad' 11. Then the movable parts of thepressing tool including the pressing ram 8, theinsulating layer 9, and the rubber pad 11 are lowered so that the'material to-be' pressed is caught between the shell-shaped mold 14 and the rubber pad 11, the'deformation' of the material being promoted and facilitated by the heattransferred to the mold 14 and the pad 11 by the heating fluid circulating in the channels 2 and the pipes 13; After'thematerial to be pressed, preferably a synthetic-material has been shaped, the heating. fluid circulatingiin'the channels 2 and the pipes 13 is replaced by a cooling agent which circulates through the channels 2 and the pipes 13 so that the pressed article is rapidly cooled andniay be removed from the pressing tool after lifting the

movable parts

8, 9, and 11' thereof. The pressed part is then removed and the pressing tool is ready for a further operation.

The shell-shaped mold 14 consists preferably of steel and is so thin, for instance 12-18 millimeters thick, that it may be manufactured from a flat steel plate which in the fiat condition thereof is machined and finished and provided with the heating channels 2. After performing these steps the plate is pressed in warm condition in a swage shown in cross-section in Fig. 6 andconsisting of a-lowerpart 63 and an upper part 64. In many cases the base member 3 shown in Fig. 1 may be formed so as to be usable as part of a swage for imparting to the mold'14 the final shape thereof.

The foil 19 consisting preferably of rolled lead facilitates any displacements of the mold 14-against the heat insulating layer 6.

Referring now to the modified embodiment shown in Fig. 7, a shell-shaped mold-714 is attached on the lower side thereof by a welding joint 70 to a relatively short threaded sleeve 71 into which the end 72 ofaholding screw 30 projectsthrough the base member 73 and the heat insulating layer 76. v

Referring now to Figs. 8 and 9 of the drawings showing' a mold for manufacturing highly deformed molded pieces, the mold' 814 is shaped as a part manufactured from a steel plate having a uniform thickness t. The mold 814'is' secured to an auxiliary'member 831 having a smooth and continuously curved lower side 809 enabling the auxiliary member 831' to yield to, and if desired, to slide on, the supporting or base member (not shown) under the influence of heat, particularly during the heating up stage. If the auxiliary member 831 consists of heat insulating material the heat insulating layer 6 shown in Fig. 1 may be omitted. The heat insulating member 831 is preferably subdivided 1nto square fieldsby fillets or bars 810. Onthe lower side of the mold- 814' are provided heating channels 811 which are limited by chutes 821 welded by welding material such as 812 to the lower side of the smooth mold 814. Ifd'esired, the mold 814 may be held inposition by screws such' as 816 arranged in a boring of the auxiliary member 831 and engaging a countermember as nuts 815 provided on the lower side of the mold 8 Referring now to Fig. 10 of the drawings the mold 1014' is' formed as a cast piece provided with heating channels 1002' arranged in the" mold' 1014.

Referring now to Fig. 11 of the'drawings a pressing tool is shown for pressing parts having unilaterally raised left and right hand edges. The base member 1103 is provided in the center thereof with an expansion joint 1124. The left part 1114 and the right part 1114a of the mold are provided, respectively, with

portions

1116 and 1116a having a reduced thickness and being connected by a holding ledge 1123 secured in position by meansof a screw bolt 1125 extending through the expansion joint 1124. A metal sheet 1122 covers the holding ledge 1123, the sheet 1122 joining to each other the parts lil l'and 1114a of the mold 1114. A heat insulating layer 1106 is subdivided by separating fillets or bars 1110 into square panels-similar to those shown in the embodiment shown in Fig. 1.

Referring now' to Pig's. 12-14 of the drawings, a mold is shown intended for the manufacture of large-dimen sionedmoldedpieceshaving upright edges which either extend overthe wholecircumference of the molded piece or are provided-on two'opposite parts thereof; As shown in Figs. 12 and 14 the mold consists of two parts 1214 and 1214a'similar to those shown in Fig. 11. The expansion joint 1224 arranged between

the'two halves

1214 and 1214a of the mold is covered by a metal strip 1229 welded to one of the halves, for instance 1214 by a welding seam1230. Between the free edge of the metal strip 1229 and the other half, say 1214a,-of the mold a groove 1226 is formed which has a width changeable according to the heat expansion of the metal strip 1229, the synthetic material (not shown) during the pressing step filling the groove 1226. On the lower side of the

halves

1214 and 1214a of the mold are provided

fingers

1227, 1228 covering the lower end of the expansion joint 1224 and welded, respectively, by welding joints or

seams

1225, 1232 to the parts of themold. As will be seen from Fig. 13 the

fingers

1227, 1228 are welded alternately to the parts 1214 and 121%; of the mold, the finger 1228 beingwelded by the welding seam 1232 to the part 1214, The part 1214 of the mold is separated by a gap 1234 from a centering member 1204 held by screws 1205 on the base member 1203 and holding the insulating layer 1206 in position, the insulating layer 1206 supporting the part 1214 of the mold. The. right part 1214a is provided with a-cen'tering member 1236 held in position on the base'member 1203 by a screw 1238'.

Although the present invention has been described hereinabove with reference to the embodiments of a pressing tool shown in" the drawings it'should'be understood that the present invention" is' in no way limited to the embodiments shown in the'drawings and that various modifications thereof, changes, and substitutions of equivalents will be apparent to" those skilled in the art, the embodiments of a pressing tool described'-hereinabove being only to be understood as examples of the present invention.

We claim:

1. A'molding tool adapted topress-mold synthetic material of relatively large area comprising, a rigid base; a heat insulating layer anchored to said base; and a mold liner of relatively hard, heat conducting material nested on said insulating layer, said insulating layer being Iinterposed between said base and said liner andthereby substantially insulates the former from the latter, said liner having an exposed surface adapted to receive material to be'molded and also having at least one channel for carrying fluid for varying the temperature of said liner, said liner being slidable supported and loosely arranged on said insulating layer for relative displacement therebetween to accommodate relative thermal expansion and contraction, and a rolled lead foil interposed between said insulating layer and said liner to facilitate relative displacement between said liner and said insulating layer.

2. A moldingtool adapted to press-mold synthetic material of relativelylarge area comprising, a'rigid base; a

heat insulating layer anchored to said base; and a mold liner of relatively hard, heat conducting material nested on said insulating layer, said insulating layer being interposed between said base and said liner and thereby substantially insulates the former from the latter, said liner having an exposed surface adapted to receive material to be molded and also having at least one channel for carrying fluid for varying the temperature of said liner, said liner being slidable supported and loosely arranged on said insulating layer for relative displacement therebetween to accommodate relative thermal expansion and contraction, the rim of said liner is slidingly supported with respect to said heat insulating layer.

3. A molding tool adapted to press-mold synthetic material of relatively large area comprising, a rigid base; a heat insulating layer anchored to said base; and a mold liner of relatively hard, heat conducting material nested on said insulating layer, said insulating layer being interposed between said base and said liner and thereby substantially insulates the former from the latter, said liner having an exposed surface adapted to receive material to be molded and also having at least one channel for carrying fluid for varying the temperature of said liner, said liner being slidable supported and loosely arranged on said insulating layer for relative displacement therebetween to accommodate relative thermal expansion and contraction, said liner has a plurality of .channels open towards said insulating layer, further comprising, cover sheet means arranged on the open sides of said channels, and filler strips arranged between said cover sheet means, said filler strips and said cover sheet means forming a smooth contact surface slidingly engaging said insulating layer.

4. A molding tool as claimed in claim 2 further comprising, stops secured to said base member, said stops being positioned to limit the relative displacement between said liner and said insulating layer.

5. A molding tool adapted to press-mold synthetic material of relatively large area comprising, a rigid base; a heat insulating layer anchored to said base; and a mold liner of relatively hard, heat conducting material nested on said insulating layer, said insulating layer being interposed between said base and said liner and thereby substantially insulates the former from the latter, said liner having an exposed surface adapted to receive material to be molded and also having at least one channel for carrying fluid for varying, the temperature of said liner, said liner being slidable supported and loosely arranged on said insulating layer for relative displacement therebetween to accommodate relative thermal expansion and contraction, said liner comprises to two adjacent sections defining an expansion joint therebetween.

6. A molding tool as claimed in claim 5, and a metal strip welded to the rim of one of said first and second liner sections and extending to overlap the expansion joint between said first and second liner sections.

7. A molding tool as claimed in claim 5, and fingershaped members securing the edges of said first and second liner sections in position along the expansion joint.

8. A molding tool as claimed in claim 7, said fingershaped members being secured alternately to the lower sides of said first and second liner sections so as to engage the edges thereof along the expansion joint.

9. A molding tool adapted to press-mold synthetic material of relatively large area comprising, a rigid base, a heat insulating layer anchored to said base, and a mold liner of relatively hard, heat conducting material nested on said insulating layer, said insulating layer being interposed between said base and said liner and thereby substantially insulates the former from the latter, said liner having an exposed surface adapted to receive material to be molded and also having at least one channel for carrying fluid for varying the temperature of said liner, said liner being slidable supported and loosely arranged on said insulating layer for relative displacement therebetween to accommodate relative thermal expansion and contraction, a countermember, a heat insulating layer anchored to said countermember, and a die member of elastic material, said material being uniformly solid throughout its body, said die member being vulcanized to said last-mentioned insulating layer and having a deformable surface turned toward the exposed surface of said liner, said last-mentioned insulating layer being interposed between said countermember and said die member, said deformable surface being urged into contact with the material to be molded upon said countermember and base member being forced together under pressure, and said die member being provided with channels for carrying a fluid for changing the temperature of said die member, and a frame enclosing said die member, screw means supported in said frame, nut means arranged for cooperation with said screw means, said nut means consisting of a vulcanizable material embedded in said die member and hollow distance pieces arranged between said frame and said nut means, said screw means extending through said hollow distance pieces.

References Cited in the file of this patent UNITED STATES PATENTS 1,389,905 Scavini Sept. 6, 1921 1,481,743 Roberts Jan. 22, 1924 1,527,206 Marquette Feb. 24, 1925 2,092,880 Hunter et a1. Sept. 14, 1937 2,311,561 Miller Feb. 16, 1943 2,368,327 Rose Jan. 30, 1945 2,458,864 Lindsay Ian. 11, 1949 2,478,165 Collins Aug. 2, 1949 2,627,628 Pare Feb. 10, 1953 2,714,226 Axelrad Aug. 2, 1955