US1514167A - Method of assembling tubes and liners in gun manufacture - Google Patents

Description

i iim a a l 3,1416? R. c. MORGAN ET'AL METHOD OF ASSEMBLING TUBES AND LINERS IN GUN MANUFACTURE Filed Jan. 11, 1922 Patented Nov. l, l fl l.

i s'r REES C. MORGAN AND JOHN F. PELLY, 0F BETHLEHEM, PENNSYLVANIA, ASSIGNORS TO BETHLEHEM. STEEL COMPANY, OF BETHLEHEM, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

METHOD OF ASSEMBLING- TUBES AND LINERS IN GUN IEANUFACTURE.

Application filed January 11,1922. Serial No. 528,573.

To all whom it may concern:

Be it known that we, Runs C. MORGAN and J orrn F. PELLY, citizens of the United States, and residing at Bethlehem, Lehigh County, State of Pennsylvania, respectively, have invented certain new and useful Improvements in Methods of Assembling Tubes and Liners in Gun Manufacture, o which the following is a specification.

This invention relates to methods of assembling liners and tubes of guns of large caliber.

It is a practically universal practice in gun manufacture to provide the liner with one or more forwardly facing annular shoulders which are designed to abut against corresponding rearwardly facing annular shoulders formed on the inside of the tube. These shoulders are intended to prevent the liner from creeping toward the muzzle of the gun in service, due to the mandrelling-out ef fect of the projectiles passing through the bore at high speeds, and to the eifect of the powder pressure. In the shrinkage method of assembling the tube and liner the latter is usually placed in a vertical position and either cooled internally by water jets or kept at ordinary room or shop temperature, while the tube is heated and expanded so that the diameter of its bore is greater than the outer diameter of the liner, after which the tube is lowered over the liner and cooled, when it frictionally grips the liner with great force, in a well known manner. It is essential that the one or more shoulders of the liner be seated against the corresponding shoulders of the tube when the assembly is complete, otherwise the liner will creep forward in service, which is objectionable for a number of reasons.

Heretofore it has been very diificult to assemble the tube and liner in such manner that the corresponding shoulder or shoulders are properly seated, largely due to the fact that the hot tube on being dropped around the cool liner causes the latter to expand and contact with the tube at a number of points along its length, and very often toward the muzzle end of the gun, before contact is made at the breech end. Also, as the muzzle end of a tube is of less thickness it cools more quickly and tends to grip the liner first. As the tube contracts longitudinally, as well as-diametrically upon coolin is obvious that if it has first gripped the liner in front of a shoulder, that as it contracts longitudlnally the shoulder of the tube will recede from the shoulder of the liner, to cause an undesirable gap between the shoulders. If the tube were to first grip the liner in rear of the forwardly facing shoulder of the latter, obviously the shoulders would be drawn together as the tube cools, but this practically never takes place because of the relatively great thickness of the tube at the breech end where it may comprise several concentric cylinders, as compared with its thickness at the muzzle, the heavier breech end being much slower in cooling.

Furthermore, as a direct result of the frictional gripping of tube and liner at-a number of points as the tube cools, the liner is forceably longitudinally contracted by the heavier cooling and longitudinally contracting tube and the resulting gun has a liner which is not only under an initial longitudinal compressive stress, which is very undesirable, but in which the fconr pression, or the actual shortening of the diameter of the bore of the liner may Vary widely from the theoretical compression desired.

It is the object of thepresent invention to provide a method of assembling tubes and liners by shrinkage whereby the corresponding shoulders of tube and liner are firmly and positively seated and longitudinal shortening of the liner prevented so that the liner of the resulting gun is not under initial longitudinal compression; and in which the actual compression realized closely approXi mates the desired theoretical compression.

The method will be described below, and an apparatus for carrying it out is illustrated in the accompanying drawings in which;

Figure 1 is a longitudinal sectional View through an assembled tube and liner, showing the apparatus in operative position; and Figure '2 is an enlarged partial section through a portion of the apparatus. i

In application, Serial No. 528,575, filed January 11, 1922, is described and claimed an apparatus for holding a liner againstlongitudinal contraction as itis assembled with a tube, and in Figure 1 of the drawings of the present application we have illusessentially a steel shaft 10 which extends.

through the bore of the linenbeing held centrally therein by annular spacing members .11. Th'e'upper end of this bar 10 has connectedthereto a'plug 12, which has screwthreaded engagement with the muzzle end of the liner itself,and the-breech end of the bar 10 is connected or secured to a power device preferably hydraulic, indicated at 13. Swinging arms '14 having hooked ends 15 arealsovsecured to the power mechanism 13, which is adapted when actuated, to effect relative movement between the bar 10 and the arms 14:, drawing the tube rearwardly and moving the liner forwardly. Because of the engaging annular shoulders of the tube and liner, indicated at 16, the liner is held against longitudinal contraction between the offset 16 and itsmuzzle end, thereby insuring, when the assembly has been completed, a gun in which the liner is "under no initial longitudinal compression.

In order to insure that "the tube and liner shall first engage at the breech or first r shoulder of each, means is provided "for 'he'atingthe liner at this section sulfrciently 'to cause an expansion thereof to such an extent "thatitwilliwithout fafil be the first section "to engage the corresponding section of the tube as the latter graduallycontracts while cooling. "It is not necessary to heat the liner to "a high temperature 'to bring about "thisre'sult, and we therefore preferablyemploy hot water or steam as a heatingmedium. "On the shaft 10 are positioned rings .19 and'QO, clearly illustrated [in section in Figure 2, these rings being provided with packing strips. The uppermost packing stripsfare designed to permit a slight leakage offluid around them and the .plug '12 is providedwitha vent '12 to 'allowthe escape of air. Conduits are formed .in the rear portion ofthe column 10 for the passage of fluid, a steam or hot water inlet conduit being indicated at'21 and an outlet conduit at 22. To the outer ends ofthese conduits may be connected flexible fluid conduits for conducting the heated fluid. to the conduit 21,.and away from the outlet of the conduit 22. By these means steam or hot water may beeontinually circulated :in the annular space around shaft 10; and between :the rings 19mm 20, thereby heating this section of the liner and causing itsexpansion in the desired manner.

In carrying out the method the plug 12 is first screwed "into prepared threads in the muzzle end of the liner and the liner placed .around vertical shaft 10,being-supported only at its anuzzleend. The heated tube is then lowered into position over the liner, with its entire weight resting on the shoulders of the liner. Steam is then introduced into the annular space between rings 19 and 20 and the flow of steam is kept up until the liner has been heated sufliciently to give asufficient diametrical expansion to insure that the expanded section will be the first section to contact with thecooling and contracting tube. Leakage of steam around the upper rings 20 causes the heating and expanding of a section of the liner above this ring and, due to the rising steam, this e2;- pansion slowly progresses upwardly. 'VVhen the steam has been shut off the hydraulic power mechanism is operated to exert an upi ward force at the muzzle of the liner and a downward force on the tube to positively prevent the longitudinal contraction .of the tube or to slightly stretch the same, if found desirable. Preferably the power is applied in stages, being increased from time to time during the cooling of the tube.

The heat from the internal heating plant and the heat passing to the liner by conduction after it 'has engaged the hot tube is gradually transmitted in both directions along the liner, causing-the successive expansionof sections and gradual gripping of liner and tube throughout their lengths. flhegradualheating of the liner also causes its'gradual extension in both directions. As a iresult'of this method or assembling the shoulders of the tube and .liner are not only correctly seated but longitudinal compres- SIVB stresses in the liner of the finished gun are practically avoided.

"Th apparatus may be modified in various ways as "will be obvious to those skilled in the art. It is simple, inexpensive to construct and, operate and thoroughly 'effi- 'cient, being effective in causing the liner and tube togripgprimarily at any section selected and'thereby enabling the operator in the shrink pit to be assured that in the assembling operation the various shoulders of the tube and 'liner are properly seated and that objectionable longitudinal compressive stresses will not bepresent.

Having thus described the invention "what we claim as new and desire to secure 'by Letters Patent is:

1. 'The method of assembling a tube and linerby shrinking,consisting in expanding the tube by heat, placing the tube over the liner, .and expanding a section of the liner by heat.

2. The method of assembling a tube which diminishes in thickness from one end to the other and a liner by shrinking, consisting in expanding the tube by heat, in

3. A method of assembling the tube and liner of a built-up gun having cooperating shoulders near the breech end, consisting in expanding the tube by heat, in placing the tube around the liner, and in expanding a section of the liner at, or in the region of, the shoulders While the tube is cooling.

a. A method of assembling a tube and liner, said tube being thicker at one end than at the other, consisting in expanding the tube by heat, in placing the tube around the liner, and in expanding a section of the liner in the vicinity of the thick end of the tube while the latter is cooling.

5. A method of assembling a tube and liner, said tube being thicker at one end than at the other, consisting in expanding the tube by heat, in placing the tube around the liner, and in expanding a section of the liner in the vicinity of the thick end of the tube by applying heat internally of the liner while at the same time allowing the tube to cool.

, 6. A method of assembling a tube and liner having shoulders to be seated consisting in expanding by heat thetube along its entire length, placing the expanded tube over the liner, expanding a limited section of the liner by applying steam to the interior of said section of the liner, and cooling the tube to cause it to shrink and grip the liner, throughout the length thereof, but first at the previously expanded section of the liner.

7. A method of assembling a tube and a liner having shoulders to be seated, consisting in expanding the tube by heat throughout its length, in placing the expanded tube over the liner with the shoulders in contact, in expanding the liner diametrically at the region of a shoulder thereof near one end to secure contact of the tube and liner first at that region while at the same time allowing the tube to cool.

8. A method of assembling the tube and the liner of a built-up gun, the tube having a plurality of interior shoulders facing the breech end and the liner having a plurality of shoulders facing the muzzle end, in expanding the tube by heat throughout its length, in placing the tube over the liner with at least the shoulder near the breech end in contact with the corresponding liner shoulder, and in expanding a section of the liner in the vicinity of the shoulders nearest the breech end to secure contact of the liner with the tube first in that region and then in progressively expanding the liner by heat to secure progressive contact thereof with the tube from said region toward the muzzle end while at the sametinie allowing the tube to cool.

9. The method of assembling a tube and liner, consisting in expanding the tube by heat, placing the tube over the liner, expanding a section of the liner by heat, stretching or elongating said liner and shrinking the tube on the liner while the latter is in an extended condition.

10. The method of assembling built-up guns, consisting in heating and expanding a tube, placing the tube over a liner, expanding a section of the liner by heat, shrinking said tube upon the liner, and

positively preventing longitudinal contraction of said liner.

In testimony whereof we hereunto affix our signatures.

REES o. MORGAN. 5 JOHN F. PELLY.

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