Foundry moulding machines and pattern equipment ...

Front matter

Class

Book.

r\

Introduction

TOURING the past years marvelous advances have been made in the amount of production obtained from the daily efforts of man, This is true not only in the industrial establishments, but is true in practically all walks of life, and especially does this fact stand forth in our home life, transportation, trucking, farming, merchandising, and in the industrial arts ; it is evident in the steel mills, machine shop, pattern shop, and in some few foundries, especially those foundries engaged in the manufacture of automobile castings. The increased production that is obtainable in these and many other lines of daily activities, has been brought about by the utilization and application of scientific knowledge, engineering principles and mechanical appliances.

This is a mechanical age. The hard, drudging, physical effort is being taken out of labor. Labor is now, in nearly all instances, being performed by the pulling of a lever, or the pressing of a button. The farm life is easy; plowing is performed by power, the wheelbarrow has become a truck, the Japanese jinrikisha an automobile, the hammer and chisel is replaced by a lathe and planer ; but to the foundry in general these contrasts will not apply, as the moulding, in some plants, is still being performed in the same manner as it has been for centuries past. The mould is still made in the old-style wood flask, hand-rammed by the same old laborious method, and very little accomplished at the day's close. Instead of being fresh and vigorous, the man is all tired out, the production small, and in many cases the castings defective.

A new day is upon us. It is here ; we cannot change it ; regardless of our individual attitude, it is here to stay ; we cannot even delay its workings ; we must launch out into the current of modern activities or the current will strand us upon the reef. Our individual effort will be judged by the amount of work produced. There will be no place for the man who is willing to work through a hard, long, day of drudgery in order to perform his daily work, but instead he who can produce as his day's work maximum production with a minimum of effort will be the one who stands the highest.

The manufacturer today is not desirous of obtaining a maximum production by means of exacting hard hours of labor, but instead, in the great majority of industries, the maximum production is obtained by mechanical means with minimum labor.

The foundry has been one of the last to adopt mechanical means of saving hard, drudging, labor, and the very fact of its being late in starting is perhaps the reason for the rapid development that has been made.

A further progress will have been made when more attention has been given by engineers to detail casting design in order to meet the foundry's requirements as to moulding methods, and by the manufacturer when ordering or having made the patterns that are to be used by the foundry.

It is with a view to stimulating co-operation between foundrymen, manufacturers, and engineers that this book is written. Their working together will be the means of producing the world's ever increasing casting supply in an easier and better way. The author, believing that pictures are of great value in the presentation of ideas, has endeavored, by a very liberal use of engravings, to illustrate the method of mounting patterns, and the making of moulds by machine power.

A Study in Contrasts

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A Study in Contrasts

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Contents

CHAPTER PAGE

I. The Theory of Jolt-Ramming. . . .' 1-7

Imperfections of hand rammed moulds 1

CHAPTER I Theory of Jolt-Ramming

Every foundryman is familiar with the skill required in producing- a hand-rammed mould for the pouring of a casting. The mould, to be poured successfully, must be rammed in such a manner as will prevent swells, scabs, blowholes, etc. When such a performance is undertaken by hand-ramming, trouble is experienced in securing a mould with a surface upon which the metal is to lay, that. is of uniform hardness and without the adjacent hard and soft spots, which, when the metal is poured, cause the gases to flow to the soft spots instead of entering the surface of the sand without flowing.

It is obvious that the moulder with his small tamp could not, without exceptional skill, produce a surface of even strength and texture and without initial strains in the body of the sand. The pouring of the hot metal against the sand releases the strains caused by uneven ramming by taking away the binding elements, allowing the sand to flow until it becomes of uniform hardness, sufficient to withstand the pressure of the metal. This movement of the sand is the cause of the rough, uneven surfaces that are usually seen on the castings produced by hand-rammed moulds.

In contrast with the above described hand method, the iron will lie properly and the gases enter the sand uniformly in the mould that is produced by jolt-ramming on a machine.

Jolt-ramming is accomplished by the lifting of the table, pattern, flask and sand a short distance and then allowing them to drop and contact with an anvil which stops and reverses the table, pattern and flask, but allows the sand to continue onward in its descending course, producing a slipping action between the flask and sand, also producing a pressure on the sand lying nearest the pattern and pattern-plate. By a repeated number of machine blows the sand is caused to flow to the bottom of the mould and pack into the flask corners and around the pattern in a uni-

Fig. 1

Fig. 2

Fig. 3

form manner ; the jolting action of the machine causes the grains of sand to flow in the direction of least resistance, and therefore the mould is packed in an even and uniform manner and without setting up strains between the different sections.

The development of the jolt-ramming method of moulding has produced a machine that will jolt-ram a mould complete in from 5 to 30 seconds of time, operating with a strpke of 1" to 2" in length, and at a rate of 150 to 250 strokes per minute. It

Theory of Jolt-Ramming is well to point out the fact that after the mould has been properly rammed either by hand or the machine, it is many times spoiled or damaged by the moulder attempting to draw the pattern from the sand by hand; distortion of the mould takes place by rapping the pattern ; this also destroys the life of the pattern,

Fig. 4

Fig. 5

which of necessity must be made of a light and fragile material. Since the saving in time effected by means of jolt-ramming is perhaps not more than 20 to> 25 per cent of the whole, it is advisable that more time be saved by having a machine that not only jolts but also rolls over the mould, and draws the pattern from the sand. These operations are being performed by machine power in from 10 to 30 seconds of time, producing a mould that has not been distorted or broken, and leaving the patterns undamaged by rapping.

It has been found that to produce a machine that will jolt-ram a mould in the manner described in the preceding paragraphs there should be no pause in the upward action of the stroke, but, on the contrary, the upward action of the stroke should start rapidly and at the instant of table contact with the anvil, in order to prevent the moving parts from coming to rest at the end of the slight rebound stroke, due to impact only. If this impact rebound is allowed to expend itself before the table again starts on its upward stroke by means of the power, the pressure on the sand is then released and instead of pressure, the sand itself rebounds and retards or destroys the packing action. Machines that do not make use of this pressure require a longer time in which to pack the sand, and indicator cards taken from such a machine would

Fig. 6

be as shown in Figures 1 and 2, in which the extreme width of Figure 1 represents the pressure required to lift the table with equipment, and the extreme width of the shaded portion of Figure 2 represents the pressure at the time of contact. Since the indicator diagram Figure 2 shows that the pressure in the cylinder at the time of contact is only one-half of the amount required to lift the load, it is obvious that the moving parts will rebound and that, without sufficient pressure in the cylinder, the parts will, when the force of the rebound is spent, settle back again until sufficient air is admitted to the cylinder to obtain the pressure required to again lift the load.

The indicator cards shown in Figures 3-4 are taken from a machine having a balanced piston type valve, so constructed as to

Theory of Jolt-Ramming close the exhaust after the air from the previous stroke has been exhausted, also admitting- line air to the cylinder before the falling load has contacted with the anvil, resulting in the moving parts being rapidly reversed after contacting, and the sand pressure in the mould maintained during part of the upward stroke.

The width of the shaded portion of Figure 3 represents the air pressure required to lift the load ; the width of the shaded portion of Figure 4 represents the pressure developed by the downward movement of the piston acting upon the air, at atmospheric pressure in the cylinder, after the exhaust is closed, and

Fig. 7

^t~m

^r^r rr

Fig. 8

also upon the admitted compressed air ; the resulting pressure is from 10 to 20% higher than the pressure required to lift the load, and takes place at a point in the stroke just before contact is made and, therefore, does not appreciably lessen the speed of the falling parts but does, however, cushion the blow so that the force of the blow is not transmitted to the base and foundation, the contact being necessary to cause the reversal of the moving parts, which is sufficient to properly ram the sand; nor is there the heavy strain set up in the falling parts as would otherwise be the case if the whole load were allowed to fall with the full force of gravity. The action obtained in the moving parts is rapid, and at the time of contact with the anvil they are resiliently reversed in their direction of travel, while the sand, being loose, continues its pressure downward without rebounding and becoming again loose in the flask.

Figures 6, 7 and 8 show a manner in which machines are tested to determine the quality of the packing action, also uniformity of stroke and valve action.

The diagram shown in Figure 6 represents a reading made by the testing of a jolt-moulding machine to ascertain the relation of the falling parts and their load, to the relation of the valve action. This style of test is also used in ascertaining the effect of compression in retarding the inertia of the falling parts.

The diagram appearing in Figure 7 represents the packing qualities of the machine and is also used to determine the uniformity of stroke.

Figure 8 discloses an irregularity of action and indicates existing trouble, which, when overcome, should produce a diagram similar to that shown in Figure 7.

Testing diagrams, such as referred to above, are a decided benefit in producing duplicate machines. Experience has shown that the stroke which produces good packing results with one grade of sand does not always produce equal results when using a different grade, and, likewise, any decided variation in pattern and flask equipment requires an alteration of stroke to produce the same results in the same length of time.

Theory of Jolt-Ramming

BOTTOM PLATE

RAM UP RUNNER CORE

Fig. 9. Plan and Sections of a Well Designed Mould, explaining the terms used in the following Chapters.

Fig. 10. A Large Roll-Over Jolt-Moulding Machine, with Foundations cut away to show the construction underneath the foundry floor.

Chapter II

In this chapter is shown a varied line of large castings that can be advantageously made on a Roll-Over Jolt-Moulding Machine, ranging in capacity from 3,000 pounds to 12,000 pounds, with a table length of 72 to 150 inches.

The machine shown on the opposite page has a table length of 106 inches and a lifting capacity of 7,000 pounds.

The operations performed are jolting, rolling over the flask, lowering the mould on a receiving table, and drawing the pattern. These operations are accomplished by the use of compressed air at a pressure of 80 pounds per square inch.

The pattern draw on a machine of this type should be positive and extremely accurate. In some instances manufacturers require a micrometer test from each machine before shipment; the variation being held to less than .0005" per inch of travel. Lubrication is of the utmost importance, and the jolting valve and piston should be equipped with a forced-feed oiling system or some other means of supplying sufficient lubrication. Wherever possible, all working parts should be encased to prevent the entrance of sand, grit, etc.

It must be understood that the machine method of producing moulds does not eliminate any of the various operations that are ordinarily necessary for the producing of the same moulds by hand or floor moulding. The moulding machine, therefore, can only be considered a means of reducing the amount of time and labor formerly necessary to perform the same series of operations. For the purpose of illustration, the attention of the reader is directed to the views on page 12 and likewise to the production table on the opposite page. From the figures in the production table, it becomes evident that nearly 50% of the time occupied in making the drag, without the aid of a moulding machine, was used in the ramming operation.

The operations required for the producing of a drag- or cope mould on the machine shown on page 12 and the means by which those operations are performed are as follows :

It is assumed that the pattern has been secured to the table of the machine and the flask placed in its proper position and clamped to the pattern-plate. Sand is riddled into the flask to a depth sufficient to cover the face side of the pattern ; the flask is then filled with sand directly from the sand supply ; the sand conveying system shown in Figure 11 provides an easy and economical means of performing this operation (altho not a necessity and rarely used except in Specialty Foundries). After the flask is filled, the operator in charge of the machine opens a valve, admitting compressed air to the jolt cylinder thru the jolt valve; the jolt piston rises and falls, carrying with it the table on which the pattern and flask are mounted ; the mould is jolted or jarred at the rate of 100 to 160 blows per minute. (20 to 80 blows are used per mould, the number of blows necessary being dependent on the depth of the flask and density desired.) After being jolted, the flask is "butted off" and then "struck off" and the bottom plate securely fastened to the flask; iron "C" clamps (which are tightened by means of wedges driven between the clamp and the bottom plate) have been found to be excellent for this purpose. The ramming is now complete and the mould ready for rolling over.

The operator then opens an air valve, admitting compressed air to the roll-over cyclinder, which raises the table on which the pattern is mounted and, in its upward travel, rolls over the mould. The table is securely locked in this position and a car known as a "run-out car," provided with devices that level the mould, is run into the space underneath the mould ; the mould is then lowered upon the car by allowing the air in the cylinder to escape; when lowered, the leveling devices are adjusted to any unevenness of the bottom plate, after which the clamps, securing the flask to the pattern, are removed.

The vibrators, which are devices similar to pneumatic hammers, and are secured to the table upon which the pattern is mounted, are set in operation and impart a vibratory action to

Roll-Over Jolt-Moulding Machine for Large Mouids 11

the pattern serving- to loosen the pattern in the sand. This action does not perceptibly enlarge the impression of the pattern in the mould. With the vibrators in operation, the valve admitting the air to the roll-over or draw cylinder is again opened and the pattern drawn from the mould, the speed with which the pattern is drawn being perfectly controlled by the operator. The mould, now resting on the car, is next run out from beneath the pattern ; the roll-over table, on which the pattern is mounted, is unlocked and tilted slightly, after which the compressed air is released from the roll-over cylinder, and the roll-over table, with the pattern, returns to the jolting position, ready for another empty flask for making the next mould.

In order to more clearly set forth the advantages to be gained by the use of the Jolt-Moulding methods, a tabulation has been made showing the machine best adapted for producing the cope and the drag, also the production that can be obtained by the use of the two different styles of Jolt-Moulding Machines. The tabulation shows clearly that the greatest production is accomplished by the machine that produces mechanically all the operations required to make the mould.

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Fig. 11. Tunnel Segment Mould — Lower or Drag Half— Made on a Roll-Over Jolt Machine. In the view shown above, the machine is rolling over the mould after it has been jolted and bottom board clamped.

After the rolling-over operation is completed, the mould is lowered on the run-out car, shown in the rear, clamps removed and pattern drawn from the mould.

The lower view shows the completed lower half or drag mould before the core is set.

In the background can be seen the enormous production obtained, a performance which extended over a period of two years, resulting in a large saving over the hand-rammed method.

Fig. 12. Tunnel Segment Mould — Upper half or Cope — Made on a 42"x97" plain jolt-moulding machine.

Fig. 13. Tunnel Segment Casting weighing 1500 pounds, used in making tunnel linings for the New York subway system.

Quan.

Cope— 42"x97" Plain Tolt .. .

100%

Drag— 42"xl06" R. 0. Jolt

! 6

*141

670%

With sand conveying system.

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1,3 p^am |

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Fig. 14. Railway Truck Frame Steel Casting — Weight 470 pounds. The

standardization of railway equipment has resulted in large quantity production of the various castings.

The production figures given below are based on using two machines of the Roll-Over Jolt type — one for the lower or drag half and the other for the upper or cope half of the mould.

With sand conveying system.

No.

Men

IS

*40

166%

Cope-^2"xl06" R. O. Jolt

Drag— 42"xl06" R. 0. Jolt

'.'. 7

*120

470%

The shipbuilding industry has not attained the quantity production shown on the preceding pages, yet a very great saving can be made by the use of moulding machinery on smaller quantity production as is shown in the following tabulations.

The production figures given below are based on making the cope and drag moulds on the same machine.

Fig. 15. Marine Engine Cylinder Head— Weight 2400 pounds.

Cope— 60"x92" R. O. Jolt.

Drag— 60"x92" R. O. Jolt.

Quan. %

Hours Moulds Increase

9 1

9 2 100%

9 3 200%

^t

Fig. 16

Marine Engine Column — Weight 4000 pounds.

Where the quantity of castings required from one pattern is not sufficient for continuous production, or even for a full day's production, any number of different patterns can be used during the day. The changing of the pattern on the Roll-Over Jolt-Moulding Machine requires only a few minutes of time.

The production figures given below are based on making the cope and drag moulds on the same machine.

Quart.

Moulds

100%

Cope— 66"xl50" R. 0. Jolt

Drag— 66"xlS0" R. 0. Jolt

! 4

400%

A large number of machine tool castings are adaptable for machine moulding, particularly on the Roll-Over Jolt type of machine.

In some instances, where a casting does not readily lend itself to machine moulding, a slight change can be made in the design without impairing its utility or strength, thereby making it possible to mould on machines.

A

1 109"

1 i

_

B

Fig. 17

Planer Housing Casting — Weight 5000 pounds.

The production figures given below are based on making the cope and drag moulds on the same machine.

Quan.

'.'.'.'.'.'. 4

100%

Cope— 66"xlS0" R. 0. Jolt.

Drag— 66"xl50" R. 0. Jolt.

'.'.'.'. '. '. 4

400%

Milling Machine Column. Weight of Casting — 700 pounds.

A 45"x72" Roll-Over Jolt- Moulding Machine made both the upper or cope half and lower or drag half of the mould for producing this casting.

The production figures given below are based on making the cope and drag moulds on the same machine.

KJ

Fig. 18

Ouan.

100%

Drag— 4S"x72" R. 0. Jolt

'.'. 4

250%

A Milling Machine Base Casting made on a Roll-Over Jolt-Moulding Machine having an over-all flask capacity of 45" in width by 72" in length. This machine is capable of jolting and rolling over half moulds up to 4,000 pounds in weight.

Fig. 19 Weight of Casting— 1040 pounds.

The production figures given below are based on making the cope and drag moulds on the same machine.

Quan.

100%

Cope— 45"x72" R. O. Jolt

Drag— 4S"x72" R. O. Jolt

'.'. 3

350%

Fig. 20

Milling Machine Table Casting — Weight 500 pounds.

A 4S"x72" Roll-Over Jolt-Moulding Machine made the moulds for producing this casting. Its simplicity in design makes possible a large production by hand moulding, yet a very large increase has been obtained by machine moulding, as noted in the following tabulation.

The production figures given below are based on making the cope and drag moulds on the same machine.

Cope^l2"x60" Plain Jolt. .

Drag— 42"x60" Plain Jolt..

!"!.'!! 3

64%

'.'.'.'.'.'.'. 3

190%

Fig. 21. A 34"x64" Roll-Over Jolt-Moulding Machine, having a lifting capacity of 2,000 pounds.