US3461709A - Hot press insulating system - Google Patents

Description

Aug. 19, 1969 H. E. MCMILLEN 3.461,!09

HOT I PRESS INSULATING SYSTEM Filed June 2, 1967 5 Sheets-Sheet l FIG. 1.

4 /50 I30. A I06 lNl/ENTOR HARRY E. MCM/LLEN Aug. 19, 1969 H. E. MCMILLEN HOT PRESS INSULATING SYSTEM 5 Sheets-Sheet 2 Filed June 2. 1967 5 mi m; VMW WW4 HAZE/5, Mean, RUSSELL & KER/v 8- 19, 1959 H. E. MCMILLEN 3,461,709

HOT PRESS INSULATING SYSTEM Filed June 2, 1967 5 Sheets-Sheet 5 HARRY 5. Ma M/LLE/V 5y 11/5 ATTORNEYS HARP/5, Macy, Russzu 6% KERN Aug. 19, 1969 I H. E. MCMILLEN now PRESS INSULATING SYSTEM Filed June 2, 1967 5 Sheets-Sheet 4 7 f INVEAJTOR 64 HARRY E MCM/LLEA/ 5y H/S ATTORNEYS HAE'Q/57 K/EcH, R0555 & Ksezv United States Patent 3,461,709 HOT PRESS INSULATING SYSTEM Harry E. McMillen, Rolling Hills, Calif., assignor to Murdock, Inc., Compton, Calif., a corporation of California Filed June 2, 1967, Ser. No. 643,100 Int. Cl. B21d 37/16 U.S. Cl. 72-342 13 Claims ABSTRACT OF THE DISCLOSURE An insulating system for the heated interplaten working zone of a hot press comprising: heat shields respectively extending along the open sides of the working zone; refractory layers engaging the surfaces of the platens opposite the working surfaces thereof; and insulating members respectively extending along the edges of the platens. Some of the heat shields are movable to inoperative positions to permit access to the working zone. Each refractory layer comprises a plurality of separate refractory blocks bolted to the corresponding platen in such a way as to permit relative expansion and contraction of the platen and the refractory blocks.

Background of invention The present invention relates in general to a hot forming or sizing and stress relieving press and, more particularly, to a hydraulic press having heated upper and lower platens defining therebetween a heated working zone in which forming or sizing and stress relieving operations may be performed utilizing suitable dies mounted on the platens. The invention is particularly applicable to a hot press for forming or sizing and stress relieving parts made of metals, such as titanium, requiring high temperatures, e.g., temperatures ranging as high as 2000 F. or more.

Operating temperatures of the foregoing magnitude within the working zone have created numerous problems in prior hot presses for performing forming or sizing and stress relieving operations of the nature in question. For example, excessive heat losses from the working zone have been a severe problem, both from the standpoint of reduced operating efficiency of the machine and from the standpoint of the comfort and safety of the operator or operators thereof. Considering another problem, prior hot presses of the type under discussion are provided with large refractory layers behind the platens, i.e., above the upper platen and below the lower platen, to reduce heat losses from the working zone and to protect other components of the machine from excessive heat. Cracking of such large refractory layers due to differential thermal expansion and contraction of the refractory layers and the platens has been a serious problem. Furthermore, such large refractory layers are difficult and expensive to replace when cracking or decomposing occurs.

Summary and objects of invention With the foregoing as background, a general object of the invention is to provide a hot forming or sizing and stress relieving press which eliminates problems such as those hereinbefore discussed.

More particularly, a primary object of the invention is to minimize heat losses from the open sides of the interplaten working zone through the use of peripheral heat insulating means extending around the sides of and enclosing the working zone. A related object is to provide a peripheral heat insulating means comprising heat shields which extend along the respective sides of the Working zone and at least some of which are retractable into inoperative positions to provide for access to the working 3,461,709 Patented Aug. 19, 1969 zone. Such heat shields, in conjunction with other heat insulation to be discussed, render the: working zone, in effect, an enclosed furnace for more efficient operation and for greater comfort and safety for personnel.

Another object in the foregoing connection is to pivotally suspend certain of the retractable heat shields on arms extending radially from shafts adapted to be pivoted through predetermined angles to move the corresponding heat shields between their operative and inoperative or retracted positions.

Still another object of the invention is to provide a hot press having platen-edge insulating means respectively extending along the edges of the platens for minimizing heat losses by radiation from the platen edges.

An important object of the invention is to provide a platen-refractory assembly wherein the refractory layer behind the platen comprises a plurality of separate refractory blocks connected to the platen in such a manner as to permit relative thermal expansion and contraction of the platen and the refractory blocks while permitting removal and replacement of individual blocks whenever required because of cracking, decomposing, or the like. With this construction, whenever a portion of the refractory layer is defective for any reason, the situation can be remedied readily by simply replacing the corresponding refractory block or blocks, instead of a single, large refractory layer. Not only is it less expensive to replace a single block, or a limited number of blocks, but such relatively small blocks are much easier to handle, in removing and installing them, than a single, large refractory layer.

Another object is to connect the refractory blocks to the platen by means of bolts disposed in openings in either the blocks or the platen, and preferably in the latter, which are laterally enlarged substantially along lines radiating from the center of the platen. With this construction, the platen can expand and contract, relative to the refractory blocks, along lines radiating from the center of the platen, as the platen temperature increases and decreases, without imposing undue stresses on the refractory blocks. Whenever replacement of a particular refractory block, or a limited number of such blocks, is necessary, this can be accomplished readily by unbolting same and substituting a replacement or replacements.

Still another object of the invention is to provide a platen assembly comprising compression springs encircling the bolts mentioned for yieldably biasing the platen and the refractory blocks together.

The hereinbefore outlined combination of peripheral heat insulating means along the open sides of the working zone, platen-edge insulating means extending along the edges of the platens, and individually replaceable refractory blocks behind the platens, creates within the heated interplaten working zone a furnace-like environment having minimum heat losses. Not only does this make for more eflicient operation of the hot press of the invention, but it greatly increases the safety and comfort of personnel operating same, which are important features of the invention.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be apparent to those skilled in the hot press art in the light of this disclosure, may be achieved with the exemplary embodiment of the invention described in detail hereinafter and illustrated in the accompanying drawings.

Description of drawings In the drawings:

FIG. 1 is an elevational view of a hot forming or sizing and stress relieving press which embodies the invention;

FIG. 2 is a view, partially in section and partially in 3 elevation, taken as indicated by the arrowed line 22 of FIG. 1;

FIG. 3 is an enlarged, fragmentary elevational view taken as indicated by the arrowed line 33 of FIG. 1;

FIG. 4 is an enlarged sectional view taken as indicated by the arrowed line 4-4 of FIG. 3;

FIGS. 5 and 6 are enlarged views respectively taken as indicated by the arrowed lines 55 and 6-6 of FIG. 2 and respectively taken as indicated by the arrowed lines 5-5 and 66 of FIG. 7;

FIG. 7 is an enlarged, fragmentary sectional view taken as indicated by the arrowed line 77 of FIG. 6;

FIG. 8 is a fragmentary elevational view taken as indicated by the arrowed line 8--8 of FIG. 5;

FIG. 9 is an enlarged, fragmentary sectional view taken as indicated by the arrowed line 9-9 of FIG. 2;

FIGS. 10 and 11 are enlarged views respectively taken as indicated by the arrowed lines 1010 and 1111 of FIG. 2 and respectively taken as indicated by the arrowed lines 10-10 and 1111 of FIG. 12;

FIG. 12 is an enlarged, fragmentary sectional view taken as indicated by the arrowed line 12-12 of FIG. 11; and

FIG. 13 is a fragmentary elevational view taken as indicated by the arrowed line 13-13 of FIG. 10.

Detailed description of invention Referring initially to FIGS. 1 and 2 of the drawings, the hot forming or sizing and stress relieving press of the invention is designated generally by the numeral and, in the particular construction illustrated, includes a C-frame 22 the upper and lower arms of which respectively carry upper and lower platen assemblies 24 and 26 defining therebetween a heated interplaten working zone 28. As is conventional, the upper platen assembly 24 is vertically movable by means of a hydraulic cylinder 30 to open and close the hot press 20.

The lower platen assembly 26 is horizontally movable inwardly and outwardly, between a retracted, operative position, shown in FIG. 2, and an extended, inoperative position, not shown, by means of a hydraulic cylinder 32. When the lower platen assembly is in its retracted position, it rests on pads 34 on the lower arm of the C-frame 22, such pads resisting the downward force applied to the lower platen assembly by the hydraulic cylinder 30 when the press 20 is closed. The lower platen assembly 26 runs inwardly and outwardly between its extended and retracted positions on fixed and vertically movable rollers 36 and 38 carried by the lower arm of the Gimme 22. The vertically movable rollers 38 are mounted on eccentrics 40 which are pivotable to move these rollers upwardly into engagement with the lower platen assembly 26 to lift it clear of the pads 34 when it is desired to run the lower platen assembly in or out. The eccentrics 40 are operated by a hydraulic cylinder 42 through a suitable interconnecting linkage 44. The reason for making the lower platen assembly 26 movable outwardly or forwardly into an extended position is to facilitate mounting tooling, i.e., a die or dies, on the lower platen assembly.

The upper and lower platen assemblies 24 and 26 respectively include upper and lower platens 46 and 48 having working surfaces 50 and 52 which are suitably machined to accommodate the desired dies. For example, the working surface 50 of the upper platen 46 is provided with machine T -slots 54, FIG. 10, for mounting on the upper platen a die or dies matching a die or dies on the lower platen when mating dies are required. The working surface 52 of the lower platen 48 is provided with keyways 56, FIG. 5, in which the desired lower die or dies may be mounted to assure positive alignment of mating dies carried by the upper and lower platens.

In addition to being capable of forming or sizing vertically, the hot press 20 is also capable of forming or sizing horizontally by means of suitable mating dies movable along the keyways 56. The necessary horizontal forming forces are developed with a clamping action which will now be described in connection with FIGS. 1 and 2 of the drawings.

As best shown in FIG. 2, the lower platen assembly 26 carries a plurality of, e.g., four, pairs of horizontally spaced clamps 58 and 60 respectively engageable with mating dies guided by the keyways 56. The clamps 60 are individually actuated by horizontal hydraulic cylinders 62 carried by the lower platen assembly 26 so that different forming pressures can be applied to different sets of dies simultaneously. The clamps 58 and 60 of each pair are independently vertically adjustable for proper alignment with the dies of the set disposed therebetween. To achieve this, the horizontal clamps 58 are carried by and are independently vertically adjustable by vertical hydraulic cylinders 64 mounted on the lower platen assembly 26. Correspondingly, the horizontal hydraulic cylinders 62 for actuating the horizontal clamps 60 are carried by and are independently vertically adjustable by means of vertical hydraulic cylinders 66 carried by the lower platen assembly. With this arrangement, as will be apparent, the vertical positions of the various horizontal clamps 58 and 60 may be adjusted independently as required for proper alignment with the respective dies of the set or sets in use at any particular time.

The upper and lower platens 46 and 48 are preferably electrically heated by means of resistance heating elements 68 and 70, respectively shown in FIGS. 12 and 7, disposed in transverse bores 72 and 74 extending through the respective platens 46 and 48 in parallelism with the respective working surfaces 50 and 52 thereof. As respectively shown in FIGS. 13 and 8, the bores 72 and 74 for the respective heating elements 68 and 70 are uniformly spaced apart except in areas where bolts to be described hereinafter are required.

As shown in FIG. 1, the upper and lower platen assemblies 24 and 26 include ducts 76 and 78 respectively extending along corresponding edges of the platens 46 and 48. The heating elements 68 and 70 are provided with terminals, not shown, respectively located in the ducts 76 and 78. In operation, air is constantly circulated through the ducts 76 and 78 as protection against burning out of the heating elements.

With the foregoing general description of the hot press 20 as background, the insulating system of the invention for minimizing heat losses from the heated interplaten working zone 28 will now be described. For convenience, the refractory layers behind the upper and lower platens 46 and 48 will be considered first. Thereafter, the insulating means for the platen edges and for the open sides of the working zone 28 will be described.

Turning to FIGS. 5 to 7 of the drawings, the lower platen 48 is shown as formed in two symmetrical halves 80, FIG. 5, seated on a refractory layer 82, FIG. 6, formed of a plurality, shown as nine, separate refractory blocks 84 slightly spaced apart. With the particular arrangement of refractory blocks 84 illustrated, the middle row of blocks is common to both lower-platen halves 80.

As shown in FIG. 7, the refractory blocks 84 rest on a base plate 86 forming part of the lower platen assembly 26, and are secured to the base plate by bolts 88. In the particular construction lilustrated, there is one bolt 88 for each refractory block 84 and it is located at the center of such block.

The lower-platen halves and the refractory blocks 84 are interconnected in,a manner permitting relative expansion and contraction of the platen halves and the refractory blocks in directions parallel to the lower-platen working surface 52. Also, accommodations for relative expansion and contraction in directions perpendicular to the working surface 52 are provided.

Considering how the foregoing is accomplished, bolts 90 having their heads recessed into countersunk openings 92 in the lower-platen halves 80 extend downwardly through such platen'halves and through the refractory blocks 84 and the base plate 86. Lock nuts 94 are threaded on the lower ends of the bolts 90 and support washers 96 which serve as seats for compression coil springs 98 encircling the lower ends of the bolts 90 and bearing against the lower side of the base plate 86. With this construction, the springs 98 bias the lower-platen halves 80 downwardly against the refractory blocks 84, and, at the same time, they permit upward expansion due to heatmg.

As will be clear from FIGS. 5 and 6, there are two of the bolts 90 through each refractory block 84. One bolt 90 of the pair of bolts extending through each refractory block 84 in the middle row extends through one of the lower-platen halves 80, and the other extends through the other lower-platen half.

As will be clear from FIG. 5 of the drawings, the openings 92 in each lower-platen half 80 for the corresponding bolts 90 are laterally enlarged substantially along lines radiating from the center of the corresponding lower-platen half. (One bolt 90 through each lower-platen half 80 is located at the center thereof. As shown in FIG. 5, the corresponding bolt opening 92 is not laterally enlarged.) With this construction, the lower-platen halves 80 can expand and contract along substantially radial lines parallel to the lower-platen working surface 52, such expansion and contraction being relative to the refractory blocks 84.

As will be apparent from the foregoing discussion, transmission of stresses resulting from expansion and contraction of the lower-platen halves 80 to the refractory blocks 84 is minimized to minimize any possibility of cracking the refractory blocks. In the event that cracking of a particular refractory block does occur for any reason, or in the event of decomposition of a particular refractory block due to the effects of heat after prolonged use, such a block can be replaced readily, after removing the lowerplaten halves 80, without any necessity for replacing any refractory blocks in satisfactory condition. This is not true of prior single-piece refractory layers.

Referring to FIGS. to 12 of the drawings, the upper platen assembly 24 has a construction which is essentially the same as that just described in connection with the lower platen assembly 26. Consequently, it will be discussed only briefly. The upper platen 46 is formed in two symmetrical halves 100 seated against a refractory layer 102 composed of closely-spaced refractory blocks 104 suspended from a base plate 106 by bolts 108. Longer bolts 110 having their heads recessed into countersunk openings 112 in the upper-platen halves 102 extend upwardly through the refractory blocks 104 and the base plate 106 and have lock nuts 114 threaded onto their upper ends. The upper-platen halves 100 are biased upwardly against the refractory blocks 104 by compression coil springs 118 seated against the upper surface of the base plate 106 and against washers 116 in engagement with the lock nuts 114. The openings 112 in each upperplaten half 100 are laterally enlarged substantially along lines radiating from the center of such platen half. This permits unrestricted radial expansion and contraction of each platen half 100 relative to its center to minimize stress transmission to the refractory blocks 104. (In this case, there is no bolt 110 at the exact center of each upper-platen half 100. Consequently, all of the bolt openings 112 are laterally enlarged.)

As previously pointed out, the heat insulating system of the invention includes platen-edge heat insulating members respectively extending along the outer edges of the upper and lower platens 46 and 48 to minimize heat losses by radiation from the platen edges. (Exceptions are the platen edges covered by the ducts 76 and 78, which themselves act as platen-edge heat insulating members.) One such platen-edge heat insulating member is shown in FIG. 9 of the drawings in conjunction with a corresponding edge of the lower platen 48 and is designated generally by the numeral 120. It will be noted that the insulating member 120 covers not only the corresponding edge of the lower platen 48, but also covers the corresponding edges of the refractory layer 82 and the base plate 86. The insulating member 120 is removably secured in place in any suitable manner, not shown, and may be of any suitable construction. It is shown as comprising a fibrous heat insulating material 122 confined in a suitable housing 124.

Turning now to a consideration of the previouslymentioned peripheral heat insulating means for minimizing heat losses from the open sides of the heated platen Working zone 28, such means comprises, as best shown in FIGS. 1 and 2 of the drawings, a rear heat shield 126 for the rear of the working zone, a front heat shield 128 for the front thereof, and side heat shields 130 for the sides thereof.

In the particular construction illustrated, the rear heat shield 126 is made in four sections each carried by a frame 132 movable upwardly and downwardly with one of the horizontal clamp cylinders 62. (The frames 132 also carry rearwardly-extending horizontal heat shields 134 above the respective horizontal clamping cylinders 62 and vertical hydraulic cylinders 66 to protect same from heat from the upper platen 46 when the lower platen assembly 26 is moved forwardly into its extended position for a tool change.) As will be apparent, when the press 20 is closed, the rear heat shield 126 is in close proximity to the rear edges of the upper and lower platens 46 and 48 to minimize heat losses from the rear side of the interplaten working zone 28.

Similarly, when the press 20 is closed, the front and side heat shields 128 and 130 are located in close proximity to the front and side edges of the upper and lower platens 46 and 48 to minimize heat losses from the front and sides of the interplaten working zone 28. These heat shields are movable upwardly from their operative, heat insulating, positions into inoperative, retracted positions for access to the lower platen 48 and/ or the working zone 28 in general. More particularly, the front heat shield 128 is movable upwardly into its retracted position to clear any die or dies on the lower platen 48 when the lower platen assembly 26 is rolled forwardly for a tool change. The sideheat shields 130 are movable upwardly into their retracted positions for access to the interplaten working zone 28' to permit insertion of a part or parts to be formed or sized and stress relieved, and to permit removal of such parts after the desired operation has been completed.

The front heat shield 128 is suspended from cables 136 which are trained around pulleys 138 140 and 142 on the upper arm of the C-frame 22 and which have counterweights 144 attached to their ends. Whenever it is desired to roll the lower platen assembly 26 forwardly, the counterweighted front heat shield 1258 is elevated into its retracted position in any suitable manner, not shown. If desired, a suitable actuating means, not shown, may be provided for this purpose.

Each side heat shield 130 is provided at its upper edge with upstanding brackets 146 connected by pivots 148 to arms 150 carried by and extending radially from a pivotable shaft 152 parallel to the corresponding side heat shield and mounted in bearings 154 on the upper platen assembly 24. With this construction, each side heat shield 130 is pivotally suspended from the corresponding arms 150. As shown in FIG. 1 of the drawings, by pivoting the shafts 152 in directions and through angles such that the arms 150 are swung from downwardly-extending vertical positions into upwardly-andoutwardly extending positions, the corresponding side heat shields 130 are moved upwardly and outwardly from their operative positions to their retracted positions, remaining vertical as this occurs due to the pivotally suspended mountings thereof on the arms 150. Preferably,

suitable stops 156 engageable by the arms 150 are provided to limit the retracted positions of the side heat shields 130'.

The shafts 152 may be pivoted in various ways to displace the side heat shields 130 between their operative and retracted positions. As best shown in FIG. 3, the actuating means for each shaft 152 preferably comprises a double-acting hydraulic cylinder 158 the piston rod of which is connected to the corresponding shaft 152 by suitable gearing, not shown, within a gear box 160.

Each of the side heat shields 130 preferably has the construction shown in cross section in FIG. 4 of the drawings. Referring thereto, the heat shield 130 shown includes an angle-section frame 162 defining the edges of the shield and the periphery of the external surface thereof. The internal surface is defined by a screen 164 secured to the frame 162, as by bolts 166. Between the internal and external surfaces of the heat shield 130 are an inner layer N8 of fibrous insulation and an outer layer 170 of insulating board. Examples of suitable materials for the inner and outer layers 168 and 170 are Kaowool and Marinite, respectively.

With such insulating materials for the inner and outer layers 168 and 170, the temperature within the heated working zone 28 may be of the order of 2000 F., yet the outer surfaces of the heat shields 130 are cool enough to touch. The rear and front heat shields 126 and 128 may have similar constructions.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims which follow.

I claim as my invention:

1. In a hot press, the combination of (a) upper and lower platen assemblies respectively including upper and lower platens, said upper platen assembly being movable upwardly and downwardly away from and toward said lower platen assembly;

(b) means for heating at least one of said platens to provide a heated working zone therebetween;

(c) peripheral heat insulating means extending around the sides of and enclosing said working zone for minimizing heat loss therefrom;

((1) said peripheral heat insulating means including at least one movable heat shield on one side of said working zone; and

(e) means mounting said movable heat shield on said upper platen assembly for movement relative thereto between an operative position wherein it blocks heat loss from said working zone, and an inoperative position wherein it provides for access to said working zone from said one side thereof.

2. A hot press according to claim 1 wherein said peripheral heat insulating means includes another movable heat shield on the opposite side of said working zone from the first movable heat shield mentioned, said hot press including another mounting means mounting said other movable heat shield on said upper platen assembly for movement relative thereto between an operative position wherein it blocks heat loss from said opposite side of said working zone and an inoperative position wherein it provides for access to said working zone from said opposite side thereof.

3. A hot press as set forth in claim 2 wherein said mounting means respectively mount said movable heat shields for movement between their operative and inoperative positions in directions generally perpendicular to said platens.

4. A hot press as defined in claim 3 wherein each of said mounting means includes a pivotable shaft carried by said upper platen assembly and parallel to the corresponding side of said working zone and having arms pivotally connected to an upper edge of the corresponding one of said heat shields.

5. A hot press as set forth in claim 4 including actuating means connected to each of said shafts for pivoting same to move the corresponding one of said heat shields between its operative and inoperative positions.

6. A hot press according to claim 1 including two refractory layers respectively positioned adjacent the surfaces of said platens opposite the surfaces thereof which bound said working zone.

7. A hot press as defined in claim 6 including platenedge heat insulating means respectively extending along the edges of said platens for minimizing heat losses from said platen edges.

8. In a platen assembly for a hot press, or the like, the combination of:

(a) a platen having a working surface;

(b) means for heating said platen;

(c) a refractory layer adjacent and engaging the surface of said platen opposite said working surface thereof and comprising a plurality of separate refractory blocks; and

(d) means permitting a relative expansion and contraction of said platen and said refractory layer, in directions parallel to said working surface, for connecting said platen and said refractory layer together.

9. A platen assembly according to claim 8 wherein said connecting means includes a plurality of bolts extending through said platen and said refractory layer and disposed in openings in one of them at least some of which are laterally enlarged.

10. A platen assembly as defined in claim 9 wherein said laterally enlarged openings are laterally enlarged substantially along lines radiating from the center of said platen.

11. A platen assembly according to claim 10 wherein said laterally enlarged openings are formed in said platen.

12. A platen assembly according to claim 11 including means comprising compression springs encircling said bolts for yieldably biasing said platen and said refractory layer together.

13. In a hot press, the combination of:

(a) upper and lower platen assembly respectively including upper and lower platens, said upper platen assembly being movable upwardly and downwardly away from and toward said lower platen assembly;

(b) said lower platen assembly being movable horizontally relative to said upper platen assembly between a retracted, operative position in register with said upper platen assembly and an extended, inoperative position out of register therewith;

(c) horizontally opposed clamping means carried by said lower platen assembly on opposite side thereof;

(d) actuating means for said clamping means respectively connected thereto;

(e) one of said actuating means being in register with said upper platen assembly when said lower platen assembly is in its extended position;

(f) means for heating at least one of said platens to provide a heated working zone therebetween when sail lower platen assembly is in its retracted position; an

(g) heat insulating means carried by said lower platen assembly for protecting said one actuating means from heat from said upper platen when said lower platen assembly is in its extended position.

References Cited UNITED STATES PATENTS 2,944,500 7/1960 Raynes 72-342 3,015,292 1/1962 Bridwell 72342 3,025,905 3/1962 Haerr 72342 3,350,913 11/1967 Bergholdt, et al. 72-342 CHARLES W. LANHAM, Primary Examiner LOWELL A. LARSON, Assistant Examiner

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