US1654526A - Method of operating extruding presses - Google Patents

Description

Jan 3, 1928.

A. BROWN METHOD OF OPERATING EXTRUDING PRESS ES Filed April 4. 1924 2 sheets-Sheet 1 Jan. 3, 1928. 1,654,526

, A. B. BROWN METHOD OF OPERATING EXTRUDING PRESSES Filed April 4. 1924 2 sheets sheet 2 Patented Jan. 3, 1928.

UNITED STATES PATENT OFFICE.

ALFRED BRUCE ERoWN, OF CHICAGO, ILLINOIS, AssIGNoR To WEsTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0E NEW YORK.

METHOD OF OPERATING EXTRUDING PRESSES.

Application filed. April 4,

This invention relates to improvements in methods of operating extruding presses.

In general an extruding press'accommodating a large charge is more eflicient than a press accommodating a small charge. lVhen increasing the capacity of a press 1t 15 desirable to increase the length of the cyllnder and working stroke of the ram rather than the diameter because when a cyllnder bore has too great a diameter 1t 1s very diflicult to control the temperature-of the charge. Heretofore, the length of the working stroke of presses has been inpart limited because no means had been provided fonsecurmg the cap of the press in relationshlp to the hydraulic cylinder with sufficient rlgidlty and accuracy.

A prevalent way of anchoring the columns of the framework to the cap of the press and to the lugs of the hydraulic cylinder, has been either to thread the ends of the columns and anchor them to the cap and lugs by means of large nuts; or the columns are made with an integral bolt-head end and the bolt-head hooked over the corner of the cap by inserting the column in a U-sha'ped aperture in the corner of the cap, this same construction being employed in securing the lower ends of the columns to the cylinder. When employing the first mentioned means it'is very diflicult to obtain the same tension on each one of the columns due to movement between the nut and the bolt threads. The latter mentioned type is insufficiently rigid, and since the face of the bolt-head of the column is not seated throughout, foreign matter gradually seeps in at the unengaged side betwen the column and its seat, allowing corrosion and causingan unseating of the seated members. v

- A method employed in operating extruding presses has been to fill the cylinder of the press with a charge forinstance of molten lead, allow the lead to solidify and then to extrude the lead into the form required, for example, cable sheath.

In following this method of extrusion the' time required to fill the cylinderand cool the charge isfrequently as'long or longer than the actual time of extrusion and the press is inactive for one-half or more of the time. Also when employing this process it is necessary to exercise great care to obtain. uniform cooling of the metal charge which 1924. Serial N0. 704,149.

is essential to preserve the uniformity of the article formed, such as, in the case of lead alloy cable sheath, concentricity. Furthermore, during the time of refilling the extruding cylinder the small portion of metal which is immediately within the die,

may become marked with an annular ring known as a press mark and the region of this annular ring may constitute a weak spot in the article formed.

An object of this invention is to extrude matter in a substantially continuous manner and with reduced periods of inactivity of the extruding mechanism.

Other objects which are secured by this invention will be indicated hereinafter and will be particularly pointed out in the appended claims.

An extruding press may be made to accommodate a greater charge, for instance of lead, by increasing the length of the cylinder. In order to' preserve the rigidity of the press and minimize deflection which would result from an extra long ram and cylinder, the framework may be constructed as follows:

Columns are employed having a bolt-head construction, the bolt-head at either end-of the column being integral there-with. Apertures in the four corners of the cap andin the lugs on p the hydraulic cylinder are slightly larger than the bolt-head of the columns. Each column is extended through one of the four apertures in the cap and the aperture in one of the lugs on the hydraulic cylinder. Split sleeves having a fianged'portion are then placed around the ends of the columns, and the columns bearing the. split sleeves are drawn back through the apertures in the cap. and lugs until the flanged portion of the sleeves seat themselves on the outside faces of the cap and lugs. Split nuts are then inserted around threaded portions of the columns and thetwo sections of the split nuts'being held together by suitable means, the nuts are drawn up tightly against the inside face of the cap and lugs, so as to prevent an unseating of the column from its ground seat on theupper face of the cap and lower face of the lugs on the hydraulic cylinder.

An improved method of operating extruding presses which may be employed efliciently with a press having a long cylinder enter the cylinder.

and accommodating a larger supply of the material to be extruded is as follows:

The cylinder of a pressis entirely filled with a charge for instance, of molten lead. Time is allowed for the charge to solidify and then a portion only is extruded, part of the solid charge being allowed to remain in the unobstructed portion of the cylinder of the press. The ram is then withdrawn from the cylinder, the cylinder replenished with lead and then the part which had beenallowed to remain in the cylinder is extruded while the new charge is still unsolidified. By this. method one part of a' charge is being extruded, while the rest of the charge is cooling.

Referring now to the drawings in which like numerals are employed to designate similar members throughout the several views,

Figure 1 is a front elevation of a press showing .an improved framework;

Figure 2 is a detail showing a section along the line 2-2 of Figure 1;

Figure 3 is a detail showing a section along the line 3-3 of Figure 2, and

Figure 4 is across section along the line 4- 1 of Figure 1 and looking in the direction indicated by the arrows. Referring to the drawings, the invention is disclosed in an extruding press which comprises a hydraulic cylinder 10 and a ram 11, slidably mounted in the hydraulic cyl-, inder. Integralwith the cylinder 10 are apertured lugs 12, the function of. which will be described more in detail hereinafter. The ram 11 carries a die. block 13, and an extrud ng cylinder 16, said die block having an upper portion 14 and a lower portion 15, respectively. Means (not shown) is provided for raising the ram .11 carrying the cylinder 16 into a position wherein a plunger 17 may Continued upward movement of the ram 11 will cause the plunger 17 to displace any matter such as lead which may be containedin the cylinder The plunger 17 depends from a cap 18 whlch is secured in spaced relation with 'respect to the hydraulic cylinder 10 by means of four columns '19, opposite ends of which i are attached to the cap 18 and the lugs 12 by means of split flanged sleeves 20, splitnuts 21 and collars 22. The manner in which the split sleeve, split nut and collars are eminafter.

ployed will be Referring particularly to Figure 4,'spira1 borings 25 may be employed for introducing heating orcoolingmatter into the walls of the cylinder 16, the flow of matter through more fully explained here-.

in position in respect to the cylinder 16 by means of bolts 28 and nuts 29. Mounted Within the die block is a core-tube 30 (Figure 1) spaced and held in position by means of an adjusting nut 31 and a die ring 32 spaced and held in position by means of an adjusting nut 33.. Within the die block and in proximity to the core-tube 30 and the die ring 32 is a hollow chamber 35 termed a forming chamber. A press of the type pictured in the drawing may be employed for the purpose of covering a cable core 36 with lead 37 The ram 17 together with the cylinder 16 in order to function efficiently with the method of operating the press, hereinafter described, should be at least 36 inches long. Heretofore it has been considered inadvisable to employ a cylinder and ram of these dimensions, but by means of the im proved framework shown in the drawings acylinder and ram of this length may be made to function efliciently.

The four columns 19 are of exactly the same length measuring from the two inside faces ofthe column heads. Four apertures in the cap 18 and corresponding apertures in the lugs 12 are employed-with flanged sleeves 20, nuts 21 and collars 22 for anchoring the four columns to the cap 18 and cylinder 10. The flanged sleeves 20 are ground to fit snugly against the inner face of the head of the column 19 and the opposite face of said flange 20 is ground to fitsnugiy against the outside face of the cap 18 and lug 12. The sleeve portion of the flanged sleeve 20 is made to fit snugly between the upper section of the column 19 and the Walls of the apertures in the cap 18 and lugs 12.

There is consequently no play of the column in the apertures in the cap and lugs.

-The span of the several columns on ac count of the positive anchoring methodand spacing method may be made exactly the same and the cap 18 consequently may be positioned at exactly right angles to the axis of thehydraulic cylinder. Since-adjacent parts are ground to produce a perfect seat the possibility of foreign matter seeping in and unseating the column is very slight, particularly since engaged parts are at all tlmes held in a rigid position. It is possible also when this construction is used to employ shims for the purpose of compensating for irregularities.

The framework is assembled by first placing the collars 22 over theheads of the columns 19, inserting one head of each column 19 through an aperture in the cap 18, and the other end of each column through a corresponding aperture in the lugs 12 on the cylinder 10. One of the split sleeves .20 is then placed around each end of the column with the flanged portion'thereof adjacent to the column head, and the columns hear ing the flanged sleeves are then drawn back until the flanged portions of the split sleeves rest upon the outside face of the cap and lugs of the cylinder and the heads of each column rest on the faces of the flanges adjacent to them. The split nuts 21 are then placed in position on threaded portions of the columns 19. The. collars 22 are placed over the split nuts 21 and said split nuts bearing the collars 22 drawn up tightly against the inside faces of the cap 18 and lugs 12.

An efficient method of operating an extruding press of this type is as follows:

First, the cylinder 16 is filled with a molten charge, for instance of lead, up to the point A. Time is allowed for the charge to solidify and then abouthalf of the lead charge, down to the point B, is extruded. After extruding the lead down to the point B the press is returned to its original position and the cylinder replenished with a new supply of molten lead up to the point A. As soon as the lead charge has solidified sufliciently to prevent blowing out around the ram the lower part of the charge which was left in the cylinder during replenishing, is extruded.

In this manner the ten'lperature of the new charge is being decreased while the old charge which has already solidified is being extruded. By this means the time which has heretofore been lostwhile'waiting for an entire charge to solidify is partly saved.

In order to explain more in detail. the

manner in which the above described method maybe employed more efliciently than some methods heretofore used, a basis of comparison maybe established. A pressure often employed is 54,000 pounds per square inch and a common article which may be' type of cable sheath accommodates 732 pounds of lead. A press embodying an improved constructionsuch as described may have a 36 inch long 10 inch diameter ram and cylinder and will then accommodate about 1,100 pounds of lead. By employing the extruding press and the process described above, beneficial resultsare obtained wh ch Wlll be described according to the basls of comparison above set out. The

I temperature ofthe charge may be presumed to be the same in each case. r 1. Active efio'iency 0 the press By the active eificiency of a machine is meant the ratio of the actual output. to its theoretical greatestpossible output, i. e., its rate of output when functioning without a stop.

The rate of extrusion'of 2 outside diameter sheath weighing 4.805 lbs. per ft. is 27 ft. per minute, or about 130 lbs. per minute. This would represent theoretical perfect activity of the press employed.

Under a process heretofore employed, a press cylinder accommodating-732 pounds of lead was used. The time required for backing down and filling was 2.7 minutes; the time required for the charge to cool 6.5 minutes, and the extruding time 5.6 minutes, a total of 14.8 minutes for extruding 732 pounds of lead. The rate of extrusion thus averages about 49.5 lbs. per minute and this compared to the theoretical perfect activity output of 130 lbs. per minute gives an efficiency of about 38 0.

The process described above, using a 36 inch cylinder accommodating an 1,100 pound charge of lead for extrusion into 2% inch outside diameter sheath is as follows: To start operation the cylinder is entirely filled with molten lead alloy, and this charge is a then allowed to cool for 6 minutes, after which one-half the charge is extruded.

The cylinder is lowered and filled in two minutes, the new charge is allowed to cool for two minutes, and the lower half of the charge, 550 lbs, is extruded in 4.3 minutes. The actual time to extrude 550 lbs. of lead under this method is Minutes. To refill; 2 To cool 2 To extrude 4.3

Total 8.3

Since 550 lbs. of lead are extruded in 8.3

minutes, the actual lead extruded per minute is 66.3 pounds. Compared to the theoretical perfect activity output of 130 lbs. per minute, the efficiency of this new method is about 51%.

The ratio of increased output by the old.

2. Uniform temperature maintained at the die block.

When employing the old method of extruding lead alloy cable sheath, (referring to the attached drawings) the cylinder 16 was filled with molten lead up to the point A, and extruded into sheathdown to the point C. The ram 17 was then withdrawn and the cylinder 16 replenished. This method has a tendency to cause unequal cooling 'of the lead alloy in the die block, and may cause eccentricity in the sheath. This unequal cooling may be caused as folhws:

When lead alloy is extruded according to this method, the small charge of lead which remains in the 'die' block on refilling culatory system around the cylinder, and

no means can readily be provided for reheatmg the charge, once cooled. Gable extruded according to thisfmethod may have a tendency to show eccentric, form.

The reason why unequal cooling causes eccentric cable sheath is belleved to beas follows: Lead alloys are more plastic at high temperatures than at low temperatures. A more plastic mass bends more easily than a more viscous one. When the lead is colder it has a tendency to move in a straight line and compress at the lower section of the forming chamber 35, and bunches up at the lower section of the forming chamber. This causes a stress on the adjacent section of the core-tube causing it to flex so as to admit an undue thickness of lead at the lower side of the sheath. \Vhen the first part of the new charge reaches the die block it is more plastic than the lower part of the. charge and bunches up on the upper part of the sheath. As soon as all the old charge has been extruded, the sheath is perfectly concentric. In practice it is known that when the lead is cooled unequally, the cold part ofthe charge causes a heavy sheath on the bottom of the cable, and the hotter part of the charge tends to cause a heavy sheath on the top side of "the cable.

Inthe new .method above described, the lead. is extruded up to the point B, and the cylinder then refilled. Extrusion then takes place before the upper charge between A and Bhas entirely solidified.- The lead in the die block does not cool too greatly dur ing refilling because it has the mass of hot lead above it from which it receives heat by conduction. The last of the old charge if cooled too greatly is again reheated'bycoming in contact with the new charge near the point B. There is less bunch up in the forming chamber 35, and the sheath so extruded approaches perfect concentricity.

3. Quality of the: article at the press mar/b.

The cause of the so-called press mark is the annealing of an article, for instance this time the sheath is being annealed.

Tests seem to show that the annealing effect reaches its maximum in about 9.5, or that the weakness at the press mark in the old method almost reaches the maximum at the existing temperature.

According to the new method of extrudin above described, the time of refilling an cooling is 4 minutes. The annealing action is therefore decreased by more than half, and tests show that lead annealed 4 minutes has greater tensile strength and hardness than lead annealed 9.5, temperature being uniform in both cases.

This process is not limited to the extrusion of lead but may be employed in handling any matter which is extruded.

The improved framework above described is not limited to use inextruding presses, as it may be employed wherever a heavy strong framework is required.

What is claimed is:

1. A process for producing lead alloy cable sheath which consists in filling a cylinder of an extruding press with a charge of molten lead alloy, extruding part of said charge around a cable core, replenishing said cylinder with lead alloy and then beginning the extrusion of the remaining part of said charge around said cable core before the new charge has solidified.

2. A process for producing lead alloy cable sheath, which consists in filling the v cylinder of an extruding press with a charge alloy before the added half of the charge has solidified.

' 3. A method of extruding lead which consists in extruding part of a charge of solid lead from a container, allowing a portion of the charge to remain in the container, replenishing the container with liquid lead, and then extruding the remaining part of said charge, the part of the charge allowed to remain in the container being large enough so that if immediately after replenishing the container with liquid lead, the old charge be extruded at a normal, uniform rate, the. added liquid charge will have-solidified by the time all of the old charge has been extruded.

In witness whereof, I hereunto subscribe my name this 24 day of March, A. D. 1924.

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