Abstract:
A joint band assembly secures payload and drive sections of a torpedo together and subsequently separates them while the torpedo is making a run. A pair of essentially semicircular bands is arranged in a ring shape have radially inwardly extending lip portions that compressively engage circumferential rims radially outwardly extending from a separation section having first and second parts connected to the payload and drive sections. Adjacent ends of the semicircular bands are coupled together by electro-explosive devices (EEDs) that each has a tubular body portion containing an explosive charge adjacent an annular segment of the tubular body portion. The annular segment has reduced thickness as compared to thickness of the tubular body portion to assure its rupture and separation of the body portion and the interconnected bands. The serial arrangement of bands and EEDs assures separation in the event that one of the electro-explosive devices should fail to detonate, and safety wire and a bonding agent hold separated parts together after detonation to prevent scattering of fragments and possible damage to the payload or drive sections.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates generally to undersea vehicles. More particularly, this invention relates to a joint band assembly for securing and subsequently releasing a payload section from a driving section of a torpedo. 
     (2) Description of the Prior Art 
     Torpedoes and other undersea vehicles place various payloads at or near a distant target, and typically, torpedoes have a forward or payload section mounted on a propulsion, or drive section that may also contain guidance systems. Some tactical situations may require that the payload section separate from the drive section somewhere along the path of the torpedo&#39;s run, and the drive section continues onward to another area. 
     Current devices for separating these sections, particularly during a run, have not been fully effective. Some of the separation devices include so many components that reliability is compromised. Others have such amounts of explosive as to create hazards for personnel that handle them onboard prior to launch, and when some are detonated during deployment, parts of the devices, fragments and concussion may damage the payload and drive sections to prevent their proper operation. 
     Thus, in accordance with this inventive concept, a need has been recognized for a cost-effective, reliable joint band assembly for securing a payload section to a drive section of a torpedo and subsequently releasing the payload section from the drive section with fewer fragments, lower concussion, limited explosive byproducts, and lower associated hazards. 
     SUMMARY OF THE INVENTION 
     A first object of the invention is to provide an apparatus for securing and subsequently releasing a payload section from a drive section of an undersea vehicle. 
     Another object of the invention is to provide a joint band assembly for securing and subsequently releasing a payload section from a drive section while a torpedo is making a run. 
     Another object of the invention is to provide an assembly that reduces risk of damaging torpedo sections during separation of sections. 
     Another object of the invention is to provide an assembly having serially coupled electro-explosive devices that assure fail safe operation if one device fails during separation of sections. 
     Another object of the invention is to provide an assembly having a pair of serially coupled electro-explosive devices that reduce creation of metal fragments and explosive by-products during detonation. 
     Another object of the invention is to provide an assembly having a pair of nonfragmenting semicircular links to reduce hazards to propellers or control surfaces of a torpedo&#39;s drive section. 
     Another object of the invention is to provide an assembly having serially coupled electro-explosive devices containing explosive therein to reduce hazards from rapidly escaping gas created during detonation. 
     An object of the invention is to provide a cost effective joint band assembly for securing and subsequently releasing a payload section from a drive section of a torpedo that is lightweight, strong, and able to withstand the effects of corrosive marine environments. 
     The present invention provides a joint band assembly for securing and subsequently releasing a payload section from a drive section of a torpedo. A pair of essentially semicircular bands is arranged in a ring shape with adjacent ends being separated from each other. Each band has a pair of parallel lip portions inwardly extending to engage radially outwardly extending annular rims of two parts of a separation section that are respectively connected to the payload section and the drive section. The bands are coupled together at both of their adjacent ends by a separate electro-explosive device connected between the adjacent ends. Each device has a tubular body portion containing an explosive charge adjacent to an annular undercut segment of the tubular body portion. The annular segment has reduced thickness as compared to thickness of the tubular body portion to rupture when the explosive charge is detonated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein like reference numerals refer to like parts and wherein: 
     FIG. 1 schematically shows the joint band assembly of this invention securing adjacent portions of a separation section that are respectively connected to payload and drive sections of a torpedo; 
     FIG. 2 is a cross-sectional side view of joint band assembly generally taken along line  2 — 2  in FIG. 1; 
     FIG. 3 is a cross-sectional view of a semicircular band taken along line  3 — 3  in FIG. 2; 
     FIG. 4 is an enlarged cross-sectional side view of an electro-explosive device (EED) and bands taken along line  2 — 2  in FIG. 1; 
     FIG. 5 is a bottom view from inside the joint band assembly of an EED along line  5 — 5  in FIG. 2; and 
     FIG. 6 is a top view from outside the joint band assembly of an EED along line  6 — 6  in FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1,  2 , and  3 , joint band assembly  10  of this invention has found specific application in torpedo  12  to secure payload section  14  to drive section  16 . Payload section  14  can be various types of ordnance such as a mine or a sensor package that is to be transported to a remote location and released from drive section  16  while it continues on its run. Drive section  16  may also carry another ordnance or sensor package and has the necessary guidance and propulsion systems including control surfaces and counter rotating propellers or pump-jet propulsor at its aft end. 
     Torpedo  12  includes separation section  18  interposed between payload section  14  and drive section  16 . Payload section  14  and drive section  16  are sealed by watertight bulkheads, and the intermediate region between bulkheads is flooded. Separation section  18  may be made from high strength aluminum alloy and has a first part  20  connected to payload section  14  and a second part  22  connected to drive section  16 . First and second parts  20  and  22  have circumferential rims  24  and  26 , respectively, that contiguously abut when parts  20  and  22  are axially aligned and brought next to each other. Payload and drive sections  14  and  16  are connected to parts  20  and  22  by standard torpedo metal joint bands  14   a  and  16   a.  Bands  14   a  and  16   a  cover adjacent peripheral strips of the parts and sections and have attached bolts, washers and threaded inserts tightened to connect parts  20  and  22  of separation section  18  and sections  14  and  16  together. 
     Joint band assembly  10  of this invention thusly engages abutting circumferential rims  24  and  26  to secure payload section  14  to drive section  16  via separation section  18 . However, joint band assembly  10  of this invention also is capable of separating payload section  14  from drive section  16  while torpedo  12  is making a run in water. 
     Joint band assembly  10  includes two essentially semicircularly-shaped bands  30  serially connected in a ring shape by two electro-explosive devices (EEDS)  50  that function as frangible links. Semicircularly-shaped bands  30  are virtually identical, and EEDs  50  are virtually identical to secure payload and drive sections  14  and  16  together, and reliably release these sections without creating fragments that might hinder their subsequent performance. 
     Referring also to FIGS. 4,  5 , and  6 , each band  30  has lip portions  32  on opposite sides that inwardly extend to engage tapered circumferential rims  24  and  26  of first and second parts  20  and  22  of separation section  18 . Bands  30  may be fabricated from high strength aluminum alloy to exert a substantial compressive force radially inwardly on circumferential rims  24  and  26  when these bands are displaced as explained below. This compressive force on circumferential rims  24  and  26  is of such magnitude to hold them axially against each other and, consequently, secure payload and drive sections  14  and  16  together. Pocket  34  is machined in one end  30   a  of band  30 , and smooth bore  36  extends from pocket  34  to coaxially aligned larger bore, or rounded recess  38 . Other end  30   b  of band  30  has slots  44  machined in it between end portions  46  that are provided with aligned parts of traverse bore  48 . 
     Each EED  50  may be made from stainless steel or other strong and corrosion resistant material and is sized to fit within pocket  34  and keep space  34   a  between it and part  34   b  of band  30  next to pocket  34 . EED  50  has tubular body portion  52  provided with annular segment  54  of reduced thickness that acts as a separation line next to shoulder  52   a.  A shackle portion  56  is provided at one end and a threaded bore  60  is provided at the other end. Explosive charge cutter  62  is fitted into tubular body portion  52  adjacent annular segment  54 , and electrical lead  64  extends through feeder block  66  and under wire tie  68  to drive section  16 . Wire tie  68  holds all parts of electrical leads  64  and feeder block  66  on tubular body portion  52  before explosive charge  62  is detonated to avoid damage to leads during assembly and weapon handling. Fragments are eliminated in the self-contained EED avoiding possible damage to the payload and drive sections  14  and  16 . 
     Shackle portion  56  has two arms  58  provided with aligned parts of a lateral bore  70  to receive stainless steel pin  72 . Use of two arms  58  minimizes stress on pin  72 . Arms  58  fit into slots  44  in band  30  to align parts of traverse bore  48  (that is the same diameter as lateral bore  70 ) in end portions  46  of band  30  with lateral bore  70 . Pin  72  extends through aligned parts of lateral bore  70  and aligned parts of traverse bore  48  to connect this end of EED  50  to band  30 . Bonding agent  72   a  is applied to pin  72  and at least some aligned parts of traverse bore  48  to retain the pin  72  in the band  30  and permit free rotation of the EED shackle  56  about the pin  72 . 
     When explosive charge cutter  62  is detonated rupturing annular segment  54  and separating tubular body portion  52 , bonding agent  72   a  (after being cured) assures that pin  72 , shackle portion  56 , and the part of tubular body portion  52  that is attached to shackle portion  56  are retained on band  30 . This reduces the possibility of damage to payload and drive sections  14  and  16 . 
     Threaded bore  60  at the other end of EED  50  is sized and threaded to mate with threaded bolt  74  that slidably extends through smooth bore  36  in band  30 . Larger bore  38  in band  30  defines an annular bearing surface  40  about the mouth of smooth bore  36  in band  30  for head  76  of bolt  74 . 
     A spherical washer set  42  is provided adjacent annular bearing surface  40  and receives bolt  74 . Spherical washer set  42  has convex portion  42   a  that contacts head  76  as bolt  74  is tightened and concave portion  42   b  adjacent bearing surface  40 . The hole through portion  42   b  is larger than the hole through portion  42   a  so that portion  42   a  is free to rotate and be displaced relative to portion  42   b.  This relative rotational displacement prevents transfer of possibly destructive torsional or other uneven bending forces from head  76  to band  30  that may otherwise over stress the annular segment  54  and induce premature EED separation. Threaded bolt  74  can be rotated by an appropriate mating tool to engage threaded bore  60  and draw bands  30  toward each other to increase the compressive force exerted by lip portions  34  on rims  24  and  26  and preload annular segment  54 . 
     Semicircular bands  30  optionally can have a retaining aperture formed therein for mounting a lanyard. Lanyard joins bands  30  with payload section  14  or drive section  16  for keeping bands  30  and associated parts away from propellers and control surfaces of torpedo  12 . 
     Compressed steel or stainless steel spring  80  is retained on tubular body portion  52  between shoulder  52   a  at one end and stainless steel retaining ring  52   b  on shoulder  52   c.  Retaining ring  52   b  may be a high strength snap-ring type that securely engages an outer surface tubular body portion  52  and/or shoulder  52   c.  Retaining ring  52   b  may be used by itself to hold its end of spring  80  on tubular body portion  52  or may be used in conjunction with a washer to help bear the biasing force, or urging of spring  80 . Spring  80  spans the width of the separation line of annular segment  54  that is adjacent shoulder  52   a.  Spring  80  creates an additional force of about 100 pounds to help separate EED  50  when explosive charge  62  is detonated and separates, or ruptures tubular body portion  52  along rupturable annular segment  54 . 
     A safety wire  82  is tied to spring  80  and under one of the two local gaps in the bore of retaining ring  52   b  to avoid scattering of these parts and other debris and ensure that they remain with band  30  after detonation of explosive charge  62  and separation of tubular body portion  54 . The possibility of damage to payload and drive sections  14 ,  16  is thus reduced. Inspection port  84  in band  30  permits observation and checking of clearance between band  30  and the outside surface of retaining ring  52   b  or tubular body portion  52  of EED  50 . Such checking assures that EED  50  does not contact band  30  to such an extent that it becomes twisted, possibly jammed and/or breaks part  34   b  of band  30  after threaded bolt  74  is tightened. 
     The tensile load at one end of EED  50  is transferred from one end  30   a  of one band  30  through bolt  74  and distributed to spherical washer set  42  on annular bearing surface  40  to minimize bending moments on the separation zone of EED  50  adjacent annular segment  54 . The tensile load on the other end of EED  50  is transferred from the other end  30   b  of the other band  30 , through end portions  46 , through pin  72 , and to two arms  58  of shackle portion  56 . These loads are equally shared by arms  58  of the EED attached with bolt  74  to bearing surface  40  on one band  30  and end portions  46  in the other band  30 , so the possibility of jamming and over stressing is reduced. 
     Joint band assembly  10  provides a series arrangement of EEDs  50  and bands  30  to assure fail-safe operation if either EED  50  fails to detonate or otherwise not separate. Only two bands  30  are needed to span the circumference of torpedo  12  as compared to contemporary systems that have more band segment structures. Thus, pin  72  on a possibly failed EED  50  is able to pivot to open assembly  10  when the other EED  50  on the other side is initiated and thereby permit payload section  14  and drive section  16  to separate successfully. 
     Other than the insignificant amount of material that might possibly be created during rupturing of annular segment  54  of EED  50 , EED  50  is essentially nonfragmenting. Since explosive charge  62  is contained in EED  50 , rapidly escaping gas and noise are greatly reduced as compared to existing bolt cutter joint band systems using a four-segment joint band. 
     EEDs  50  are smaller and lighter than the explosive devices of the existing system and are potentially less expensive. Accordingly, bands  30  are not damaged by detonation so they can be retrieved and reused. EEDs  50  are coupled to larger and stronger bands  30  than those used in the existing system but do not require extra space between payload section  14  and drive section  16 . Only two EEDs  50  secure bands  30  as compared to eight bolts used in the existing system. EEDs  50  and bands  30  of this invention have at least the same structural integrity of standard joint rings and do not create fragments or other debris that might damage payload section  14  or the rest of torpedo  12 . 
     Because of the reliable design of joint band assembly  10 , EEDs  50  and pins  72  may be made from stainless steel so that assembled EEDs  50  may be stored in flooded torpedo tubes with minimal corrosion potential. This feature further distinguishes from the existing system that is plated steel and was intended to be stored in air prior to being deployed in seawater. 
     Having the teachings of this invention in mind, modifications and alternate embodiments of this invention may be fabricated. For examples, in accordance with this invention, joint band assemblies  10  could be fabricated from alternative materials, such as various aluminum and stainless steel alloys, composites, plating, welding, and coatings. These materials could be incorporated in joint band assembly  10  to minimize the thickness of bands  30  yet provide sufficient local end thickness to attach EEDs  50 . Designs could be modified to expedite mass production and further reduce costs even for more unique designs and specialized machining or multiple part band assemblies. 
     The disclosed components and their arrangements as disclosed herein all contribute to the novel features of this invention. This invention provides a reliable and cost-effective joint band assembly  10 . Therefore, joint band assembly  10 , as disclosed herein is not to be construed as limiting, but rather, is intended to be demonstrative of this inventive concept. 
     It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.