The above-mentioned types show only hand machines which have been in general use for a considerable period of time, but the last decade has shown a wonderful change in this branch of foundry practice; indeed so great is the advance that hardly a month passes that there does not appear some new featuer. The most important advancement, of course, was the adaptation of power, usually compressed air being resorted to, but more recently there has been quite a tendency to utilize electricity.
Fig. 101 shows compressed air applied to the squeezer type of molding machine. This machine is designed especially for use in molding light snap-flask work in large or small quantities, and the method of pattern fitting depends upon the Dumber of castings to be made from one pattern.
2. Left-hand stop for yoke.
3. Yoke handle.
4. Pressure gage 5. 1/4-inch air cock.
6. Eye bolt.
7. Left-hand strain bar.
8. Right-hand strain bar.
9. Right-hand yoke stop.
11. Knee-pad rod.
12. Air hose from knee valve to vibrator.
13. Air hose from knee valve to supply.
14. Hose guard.
15. Knee pad.
16. Knee starting valve.
17. Cylinder base.
19. Piston ring.
20. Counterbalance spring.
21. Adjustment block for spring seat.
22. Adjustment-block set screw.
24. Bracket for lower spring seat.
25. No- 5 snap oiler.
26. Trunnion shaft.
27. Pop throttle-valve lever.
28. Valve-lever stud.
29. Throttle-stop segment.
30. Valve sand guard.
31. Valve spring for exhaust.
32. Adjustable strain-bar stop.
33. Valve body.
34. L hose nipple.
35. Straight hose nipple.
36. Valve bracket.
37. Taper pins, trunnion to shaft.
38. Blow valve.
39. Blow-valve hose.
Attention is called to the fact that the production of the power squeezer exceeds that of the hand squeezer by 15 to 30 per cent. For description of various ways of mounting patterns, see Pattern-Making.
A power roll-over power-draft machine is shown in Fig. 103. This is designed to handle side floor work and has a straight draft of 8 inches and sufficient power to roll over ft weight of 1000 pounds. It will be noted that as in the hand rollover the patterns are mounted on wooden match plates, the small expense of which makes this style of machine very effective in jobbing shops where but few castings are made from a pattern at a time. In Fig. 104 is shown the latest type of this machine with the flask shown in position ready for bar ramming. Fig. 105 shows the mold partly rolled over; the mold rolled over and partly withdrawn is shown in Fig. 106. The view given in Fig. 107 shows the finished mold on one side and the pattern back in place.
Fig. 100. Roll-Over Molding Machine with Pattern Withdrawn Courtesy of Tabor Manufacturing Company, Philadelphia, Pennsylvania.
The working parts of the above machine are shown in Fig. 108, and are as follows:
1. Roll-over frame.
2. Air cylinder.
4. Wedge leveling device.
5. Adjustable support for leveling device.
6. Operating valve and lever.
The plunger is made hollow and acts as an oil tank into which air under pressure is admitted when the machine is to be operated. When air pressure is admitted to the plunger, the oil is forced through a port into the cylinder, causing the plunger to rise and by means of its link connections to roll over the mold which is deposited on the leveling device. After the flask has been unclamped air is again admitted to the plunger, causing the pattern to be drawn vertically the full draft of the machine, at which point the link connections cause the roll-over frame to return to its initial position ready to receive another flask.
Fig. 102. Elevation of Tabor Squeezer Showing Working Parts.
The jar or jolt-ramming machine is used for all classes of work from light work up to the largest floor work made in green sand, the limit being only the capacity of the machine itself, which varies from a few hundred pounds to many thousands of pounds. Large engine beds are a good example of the castings produced on the heavy-duty machines.
Patterns mounted on heavy wooden match plates are used in the manner hereafter described. The flask is first placed on the drag half of the pattern board, and the flask filled with sand. By the use of an upset, usually about 4 inches deep, it is possible to heap sufficient sand on the flask to insure its being filled after the ramming has taken place. The flask must be securely clamped to the pattern plate, when both may be listed by the traveling crane and placed on the table of the jarring machine, which in the heavy-duty machines is on the foundry-floor level; the working parts of the machine being below and resting on a rigid concrete foundation. Here, air under pressure is allowed to enter the cylinder, and, acting on the plunger, which in turn lifts the table usually about 4 inches, when the air is suddenly exhausted, allows the table to drop heavily on the anvil. The number of blows required to pack the sand must be determined by experience. The time required to ram the largest mold is but a small fraction of that consumed by hand-ramming.
Fig. 109 is an illustration of one of the simplest styles of this type of machine. Fig. 110 shows the working parts of the same machine.
A quite distinct style of jolt machine, called an electropneumatic jolt-ramming machine, is shown in Fig. 111, the unique feature being the motor-driven compressor without a clutch, spring, cam. or valve. A very little study of Fig. 112 should make clear its radical features.
Fig. 112. Section of krause Jolt Rammer Showing Transmission and unique Compressor.
Fig. 113 illustrates an automatic molding machine of the squeezer type. The operator places the flask and bottom board in position, then by simply pressing on the starting lever the filling of the flask with sand, the ramming and the drawing of the pattern is completely automatic and accomplished in about eight seconds or some six or seven hundred molds per day. This machine is best adapted to the production of small duplicate work such as small pipe fittings.
The very distinctive type of molding machine shown in Fig. 114 is known as the roller-ramming machine. It is best adapted to long work of comparatively thin cross-section, of which a cornice section would be a good example. This class of work could not be produced readily on any of the: