US3748893A

US3748893A - Method and apparatus for detecting defective shells

Info

Publication number: US3748893A
Application number: US00148528A
Authority: US
Inventors: M Spillane
Original assignee: Atlas Chemical Industries Inc
Current assignee: Zeneca Inc
Priority date: 1971-06-30
Filing date: 1971-06-01
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31
Also published as: AU4399772A; AU462129B2

Abstract

A method and apparatus for detecting defective shells. A friction seal is placed in the open end of the shell and the shell is held on the seal while a limited quantity of gas is supplied to the inside of the shell at a pressure great enough to force the shell off the seal. The shell is then ceased to be held on the seal and will be forced off by the gas pressure if the gas has not escaped through a hole or the shell is not deformed. Many shells may be tested at the same time.

Description

Elnited States Patent Spillane 1451 July 31, 1973 [54] METHOD AND APPARATUS FOR 527,989 4/l930 Germany 73/37 DETECTING DEFECTIVE SHELLS Primary Examiner-Richard C. Queisser [75] Inventor. Matthew L. Spillane, Tamaqua, Pa. Assistant Examiner DeniS E. Co" [73] Assignee: Atlas Chemical Industries, Iuc., Attorney-Kenneth E. Mulford and Roger R. Horton Wilmington, Del. 22 Filed: June 1, 1971 [57] ABSTRACT A method and apparatus for detecting defective shells.

[2]] Appl' 148528 A friction sea] is placed in the open end of the shell and the shell is held on the seal while a limited quantity of [52] U.S. Cl. 73/49.2 gas is supplied to the inside of the shell at a pressure [51] Int. Cl. G0lm 3/02 great enough to force the shell off the seal. The shell is [58] Field of Search 73/9, 37, 49.2, 49.3 then ceased to be held on the seal and will be forced off by the gas pressure if the gas has not escaped through [56] References Cited a hole or the shell is not deformed. Many shells may be FOREIGN PATENTS OR APPLICATIONS 12/1915 Germany 73/37 tested at the same time.

10 Claims, 4 Drawing Figures PATENIEDJULSI I975 SHEET 1 UP 4 INVENTOR Matthew L. Spillane p- Bvrflw fi M ATTORNEY PATENIED JUL 3 1 M5 3 148 8 93 SHEET 2 BF 4 INVENTOR Mafthew L. Spillane ATTORNEY PATENIED FIG. 3

SOURCE v Bfiw gginz INVENTOR Matthew L. Spillane ATTORNEY PAIENTEB JUL3 1 I973 SHEEI 0F 4 INVENTOR Matthew L. Spillane BY ATTORNEY METHOD AND APPARATUSFORDETECTING DEFECTIVE SHELLS Shells used for making blasting caps must be free of defects such as holes, cracks, or deformities (e.g., outof-roundness) which would allow moisture to enter desensitizing them. The defects can also let explosive material spill out of the cap during assembly, leaving the cap less powerful and causing a dangerous situation on the assembly line. Until now, shells were not systematically tested for defects as no fast, inexpensive method of accurately testing large numbers of shells was available. Rather, a sampling of finished caps was placed in water at 150/ lbs/sq. in. and then shot. If too many failed, the entire lot had to be discarded. That method was, of course, wasteful of good caps as well as the materials that were used to fill the defective shells.

I have invented an apparatus and method for detecting defects in shells before they are filled. My method and apparatus can rapidly, accurately, inexpensively, and simultaneously test large numbers of shells. Holes so small that they cannot be seen with the naked eye are readily detectable with this invention. Also, a hole in a shell usually produces a whistle as the shell is being tested which immediately attracts the operators attention to the defective shell.

Each shell is provided with a friction seal in its open end. The shell is held on the friction seal while a limited quantity of gas is admitted into the inside of the shell at a pressure sufficient to force the shell ofi the seal were it not being held on the seal. After a short interval, the gas pressure is allowed to push the shell off the seal. If the shell is not defective, it will be pushed off; but, if it has a hole or crack in it, the gas will have escaped through the hole or crack and the shell will remain stuck to the friction seal where it can be removed and discarded by hand or by a machine. The shell will also remain stuck to the friction seal if it is deformed at the mouth so that there is a very tight fit between the shell and the friction seal.

The accompanying drawings illustrate certain presently preferred embodiments of this invention.

FIG. 1 is a front view partially in section of the apparatus of this invention.

FIG. 2 is a front view partially in section of the nipple and parts surrounding it as shown in FIG. 1.

FIG. 3 is a schematic drawing of the pneumatic system for the apparatus of FIG. 1.

FIG. 4 is an electrical diagram for the apparatus of FIGS. 1 and 2.

In FIG. 1, a main support 1 made up of many structural members, supports an air cylinder 2 which can be activated to raise or lower bed 3. To bed 3 are fixed arms 4 which ride against tracks 5. Bed 3 holds a tray 6 in which may be placed shells such as shell 7 arranged in a pattern of 7 rows of 14 shells alternating with 8 rows of 13 shells or other suitable pattern. Stops 8 and 9 are also fixed to bed 3, stop 8 being directly below limit switch 10. Upper support 11 is attached to main support 1. The upper support holds an air chamber (shown in FIG. 2) which supplies air to nipples such as nipple 12 arranged in a pattern of 7 rows of 14 nipples alternating with 8 rows of 13 nipples corresponding to the positions of the shells. Also shown in FIG. 1 are the positions of the emergency reverse button 13, the air pressure gauge 14 which shows the pressure in the air chamber, the control box 15, and a start switch l6.

In FIG. 2,

walls

17 and 18 form an air chamber 19. Nipple 12 is mounted on wall 18. A check valve 20 which permits air to flow only in a downward direction is mounted on chamber wall 18 above the nipple and air passage 21 leads from air chamber 19 through check valve 20, chamber wall 18, and nipple l2. Nipple 12 is provided with a four-lobed ring seal 22 held in recess 23. A side air passage 24 leads from air passage 21 to the inside rim of four-lobed ring seal 22. Air prssure against the inside rim of seal 22 causes it to expand outwardly, giving an excellent sealing effect in spite of small variations in the diameter of shell 7.

In FIG. 3, a source of air pressure at about lbs/sq. in. is supplied to on-off valve 25 which is connected to check valve 26 and air cleaner 27 by lines 78. Air cleaner 27 is connected to a dryer 28 which, in turn, is connected to spring-biased solenoid valve 29 which is controlled by solenoid 30. Air from this valve goes to chamber 19 (FIG. 2). Check valve 26 is connected to a second air cleaner 31, then to an on-off valve 32 and, by way of lines 33, to

solenoid valves

34 and 35; solenoid valve 34 is controlled'by

solenoids

36 and 37. Air from solenoid valve 34 goes to solenoid valves 35 and 38 by way of

lines

39 and 40 and controls these valves as will hereinafter be explained. Air from valve 35 goes to cylinder 47 and air from valve 38 goes to cylinder 42. These cylinders contain oil 43 which can flow through speed control valves 44 and 45 into cylinder 2. This cylinder contains a piston 46 which is connected by shaft 47 to bed 3 (FIG. 1). Oil is used because it gives a smoother movement than air.

The operation of the apparatus of FIGS. 1, 2, and 3 will now be described in conjunction with the description of FIG. 4.

A tray of shells to be tested is placed as shown in FIG.. 1. In FIG. 3,

valves

25 and 32 are turned to the ON position as shown. In FIG. 4, a source of electricity is provided to hot line A and 2-pole switch 48 is turned to the ON POSITION. Using an electrical convention, the contacts move up or down according to the position of the asterisk on the same side of the switch as the position to which the switch is turned. A current flows through line 49 operating dryer 28.

The operator then selects the mode of operation. There are three modes the manual mode, the dwell up mode, and the automatic mode.

In the manual mode the operator can only raise and lower the bed; this mode will be described first. Twopole mode switch 50 is set to MAN," the contacts moving to the upper position. Current now flows through

lines

51 and 52 to start switch 16, and through line 53 to a second start switch 54 (Two start switches are used so that the operator must keep both hands away from the moving portions of the apparatus). The current continues through line 55 through mode switch 50, through

lines

56 and 57 to solenoid 36. This solenoid causes solenoid valve 34 (FIG. 3) to remain as shown which lets air flow from lines 39 to valves 38 and 35. Valve 38 permits air in the top of cylinder 43 to be exhausted and valve 35 lets air flow from line 33 into the top of cylinder 41 which keeps piston 46 as shown holding bed 3 in the position shown in FIG. 1. The circuit to solenoid 36 is completed to ground by way of

lines

58 and 59.

The operator then presses switch 16 with one hand and switch 54 with the other hand. These switches are spring-biased to the position shown in FIG. 4.

Current now flows from line 52 through switch 16, line 60, switch 54, and line 61 to solenoid 37 to

lines

62 and 59. Solenoid 37 in FIG. 3 moves valve 34 so that air flows through lines 40 moving valves 35 and 38 so that air in cylinder 41 exhausts through valve 35 and air in line 33, by way of valve 38, forces oil into the bottom of cylinder 3 causing bed 3 (FIG. 1) to move so that the tray and shells will be in the position shown in FIG. 2, ready for testing. Releasing switches 16 and 54 returns bed 3 to the position of FIG. 1.

In the Dwell Up mode, the contacts of mode switch 50 remain as shown. When the operator presses

switches

16 and 54, bed 3 will rise as before, but releasing switches 16, 54, or both will not cause the bed to lower since mode switch 50 is open. The Manual and Dwell Up modes are used primarily for servicing the machine.

In the Automatic mode, the contacts in mode switch 50 move to the lower position. When the operator closes

switches

16 and 54, bed 3 rises as before. When the bed reaches its uppermost position so that the nipples have entered the shells and testing may proceed, stop 8 (FIG. 1) closes limit switch 9 (FIGS. 1 and 3). Current then flows through line 51, mode switch 50, line 63, limit switch 9, and line 64 to normally-closed switch 65 to solenoid 30 to line 59. Solenoid 30 is immediately activated and lets air flow through valve 29 from dryer 28 (FIG. 3) to air chamber 19 (FIG. 2) and, by way of air passages 21, all of the shells.

When limit switch 9 was closed, current also flowed from line 64 to

timers

66 and 67 to

lines

68 and 69, respectively, to line 59. Timer 66 opens switch 65 after the pressure in the line from dryer 28 and the pressure in the non-defective shells have had enough time to equalize (about 2 seconds). When switch 65 is opened, valve 29 returns to the position shown in FIG. 3 which exhausts air chamber 19. The pressure in the nondefective shells remains high due to check valves 20 but the air in defective shells quickly leaks out the holes and cracks and the pressure in these shells drops to atmospheric pressure. After a sufficient amount of time has passed to permit leakage through the defective shells (about 4 seconds), timer 67 closes switch 70 permitting current to flow to solenoid 36 which lowers bed 3. Air pressure in the non-defective shells forces the shells off seal 22 (FIG. 2) and they remain in the tray as it is lowered. Friction between the defective shells and seal 22 holds the defective shells on seal 22 as the tray is lowered. These shells are then pulled OE and discarded.

Closing emergency reverse switch 13 permits current to flow through

lines

71, 72, and 57 to solenoid 36 which lowers bed 3 in the event of an emergency.

It should be noted that it is also within the scope of this invention to lower the nipples instead of raising the tray.

I claim:

1. An apparatus for detecting a hole in a shell sealed at one end and open at the other comprising:

1. sealing means for sealing the open end of said shell by projecting into said open end of said shell to form a friction engagement therewith and the frictional force being sufficient to support the weight of said shell, said sealing means having a gas passage therethrough;

2. means for temporarily holding said shell and said sealing means in sealed relationship; and

3. a source of gas to said gas passage, said source being of a limited quantity, the pressure of said gas being great enough to overcome said friction and force a shell without a hole therethrough off said sealing means.

2. An apparatus according to claim 1 wherein said gas pressure is air pressure.

3. An apparatus according to claim 1 wherein a oneway valve permits gas to move through said gas passage only in the direction of said shell.

4. An apparatus according to claim 1 wherein said gas is supplied to said shell through a nipple and said means for temporarily holding said shell and said sealing means in sealed relationship is an air cylinder which moves said shell relative to said nipple until said nipple has entered said shell.

5. An apparatus according to claim 4 wherein said sealing means is a four-lobed ring seal in a recess in said nipple.

6. An apparatus according to claim 5 wherein a side passage communicates from said gas passage to the inner side of said four-lobed ring seal.

7. An apparatus for detecting holes in shells comprismg:

a. a tray for holding said shells in a vertical position;

b. nipples, each having a gas passage therethrough and each being positioned directly above a shell;

c. means for moving said tray relative to said nipples;

d. sealing means for friction sealing each nipple to the shell it projects into and the frictional force being sufficient to support the weight of said shell; and

e. means for supplying a limited quantity of gas to each gas passage at a pressure sufficient to overcome said friction and force a shell without a hole therethrough off said sealing means.

8. An apparatus according to claim 7 wherein a check valve is provided in each gas passage.

9. An apparatus according to claim 7 wherein said sealing means is a four-lobed ring seal in a recess in said nipple and a side passage communicates from said gas passage to the inner side of said four-lobed ring seal.

10. A method of detecting a hole in a shell sealed at one end and open at the other comprising:

a. inserting a friction seal having a gas passage therethrough into the open end of said shell;

b. holding said shell on said friction seal;

c. supplying a limited quantity of gas through said gas passage to the inside of said shell at a pressure greater than the pressure needed to force said shell off said friction seal;

d. waiting a sufficient amount to permit enough of said gas to pass through said hole to reduce the pressure of said gas below the pressure needed to force said shell off said friction seal; and

e. ceasing holding said shell on said friction seal.

it 1 i i

Claims

1. An apparatus for detecting a hole in a shell sealed at one end and open at the other comprising: 1. sealing means for sealing the open end of said shell by projecting into said open end of said shell to form a friction engagement therewith and the frictional force being sufficient to support the weight of said shell, said sealing means having a gas passage therethrough; 2. means for temporarily holding said shell and said sealing means in sealed relationship; and 3. a source of gas to said gas passage, said source being of a limited quantity, the pressure of said gas being great enough to overcome said friction and force a shell without a hole therethrough off said sealing means.

2. An apparatus according to claim 1 wherein said gas pressure is air pressure.

3. An apparatus according to claim 1 wherein a one-way valve permits gas to move through said gas passage only in the direction of said shell.

7. An apparatus for detecting holes in shells comprising: a. a tray for holding said shells in a vertical position; b. nipples, each having a gas passage therethrough and each being positioned directly above a shell; c. means for moving said tray relative to said nipples; d. sealing means for friction sealing each nipple to the shell it projects into and the frictional force being sufficient to support the weight of said shell; and e. means for supplying a limited quantity of gas to each gas passage at a pressure sufficient to overcome said friction and force a shell without a hole therethrough off said sealing means.

10. A method of detecting a hole in a shell sealed at one end and open at the other comprising: a. inserting a friction seal having a gas passage therethrough into the open end of said shell; b. holding said shell on said friction seal; c. supplying a limited quantity of gas through said gas passage to the inside of said shell at a pressure greater than the pressure needed to force said shell off said friction seal; d. waiting a sufficient amount to permit enough of said gas to pass through said hole to reduce the pressure of said gas below the pressure needed to force said shell off said friction seal; and e. ceasing holding said shell on said friction seal.