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US3302442A - Production of lead shielding bricks - Google Patents

Production of lead shielding bricks Download PDF

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Publication number
US3302442A
US3302442A US335911A US33591164A US3302442A US 3302442 A US3302442 A US 3302442A US 335911 A US335911 A US 335911A US 33591164 A US33591164 A US 33591164A US 3302442 A US3302442 A US 3302442A
Authority
US
United States
Prior art keywords
brick
lead
die
punch
bricks
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US335911A
Other languages
English (en)
Inventor
Broek Sidney E Van Den
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Graviner Manufacturing Co Ltd
Original Assignee
Graviner Manufacturing Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Graviner Manufacturing Co Ltd filed Critical Graviner Manufacturing Co Ltd
Application granted granted Critical
Publication of US3302442A publication Critical patent/US3302442A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B9/00—Presses specially adapted for particular purposes
    • B30B9/32—Presses specially adapted for particular purposes for consolidating scrap metal or for compacting used cars
    • B30B9/327—Presses specially adapted for particular purposes for consolidating scrap metal or for compacting used cars for briquetting scrap metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/02—Die forging; Trimming by making use of special dies ; Punching during forging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K5/00—Making tools or tool parts, e.g. pliers
    • B21K5/02—Making tools or tool parts, e.g. pliers drilling-tools or other for making or working on holes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/02—Dies; Inserts therefor; Mounting thereof; Moulds
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
    • G21F3/04—Bricks; Shields made up therefrom

Definitions

  • This invention relates to the manufacture of lead bricks, in particular lead shielding bricks which are used for providing shielding against nuclear radiation. Except where otherwise indicated, the word lead is used herein to include alloys of lead with small quantities of other metals, such as 4% of antimony.
  • Porosity in bricks caused by such voids and fissures either render the bricks unsuitable for shielding purposes or reduce their shielding value. If porosity is to be allowed for, the brick must be made larger than would be required in the case of a non-porous brick.
  • the disadvantages mentioned above may be substantially alleviated by the method of forming bricks according to the present invention.
  • the present invention provides a lead brick brought to a predetermined contour by pressing in the solid state.
  • the present invention also provides a method of forming such a brick, and apparatus for performing this method.
  • FIGURE 1 is a vertical section through a die for cold forming lead bricks.
  • FIGURE 2 is a section on the line IIII of FIG- URE 1.
  • FIGURE 3 is an isometric view of a typical lead brick which may be formed with the apparatus of FIGS. 1 and 2, and
  • FIGURE 4 is a vertical section through a female punch.
  • apparatus for cold forming lead bricks comprises a die 11 formed of hardened tool steel having a circular periphery and a die cavity 12 which matches the cross-section of the lead brick to be formed, this die cavity being of constant cross-section throughout its length.
  • the die is supported within a die support or bolster 13 which is bolted to the bed of a high pressure hydraulic press (not shown).
  • the upper and lower ends of the die cavity are closed by punches 14 and 15 whose longitudinal surfaces match the internal surface of the die cavity.
  • the operative faces 14a and 15a of the punches are profiled to the shape of the corresponding surfaces of the lead brick to be formed.
  • the lower punch has a male surface 1411 designed to form a corresponding female surface in the lower face of the brick whilst the upper punch has a female surface 15a designed to form a corresponding male surface on the upper face of the brick.
  • the upper punch can have the male surface and the lower punch the female surface. In fact, this arrangement is preferable since the female punch has a tendency to spread under the applied pressure and such spreading of a moving punch could result in binding of the punch with the walls of the die.
  • Spew gates are provided for allowing excess lead to be squeezed out of the die along one or more surfaces of at least one of said punches. These spew gates may be formed by grooves 14b in the lower punch 14. However, it is preferred to make the upper punch slightly undersize along at least two opposite sides thereof, preferably the sides adjacent the inclined working surfaces of the punch, so that the lead spew will take the form of thin sheets of lead which emerge from the die along said opposite sides of the upper punch.
  • FIGURE 3 This is a corner brick of relatively complex shape.
  • the more conventional shape of a brick is chevron shape, that is to say having a V section projection extending across the full width of one end of the brick and a V section recess extending across the full width of the opposite end of the brick.
  • a precast lead blank whose volume is in excess of the volume of the desired finished brick, is placed within the die and after insertion of the upper punch, a very high pressure is applied to the die by the press to cause the lead blank to be transformed into a fluid state in which it can flow into the shape of the finished brick, excess lead being squeezed out through the spew gates.
  • the lower punch has an enlarged head 14c and the upper punch an enlarged head 150 which define the limit of insertion of the punches into the die and therefore define the size of the finished brick.
  • the upper and lower punches are removed and a similarly shaped brick of slightly smaller cross-section is inserted in the die above the finished brick and the top punch replaced and pressed downward to expel the shaped brick from the bottom of the die.
  • the lower punch can be provided with a very long stem so that after pressing of a brick to shape, the upper punch is removed and the lower punch is raised to expel the brick upwardly. The only further operation required to produce a finished brick is the removal of lead flash.
  • the blank to be used for forming the brick preferably conforms very approximately to the internal shape of the die, this is not believed to be necessary and a blank of almost any shape may be placed in the die and pressed to form a shaped brick.
  • the internal surfaces of the die and of the punches are polished to provide a smooth or mirror finish, and substantially the same degree of finish will accordingly be imparted to the surfaces of the shaped brick.
  • the operation of pressing the brick out of the die will even further improve the surface finish on the surfaces of the brick contacted by the die. It is believed that such a high degree of surface finish is impossible to achieve by any of the existing lead shaping methods.
  • a blank of lead containing 4% antimony and weighing 28 pounds was placed in a die of 4 inches by 2 inches crosssection and 8 inches length.
  • the upper punch was smaller by one millimeter along two opposite sides than the cross-section of the die thus providing two spew gates each one millimeter in width along two opposite sides of the die.
  • the die was closed by inserting the upper punch after which pressure was applied and built up to 40 tons per square inch. At this pressure, the lead was transformed into the fluid state, the excess lead was pressed out of the die and simultaneously the pressure dropped to 35 tons per square inch.
  • the finished brick, after removal from the die was found to Weigh 26 pounds, and was found to have a density of 0.406 pound per cubic inch. This is in comparison with a density of 0.393 pound per cubic inch in the lead blank.
  • the density of the brick is made substantially greater than that of a cast brick, in other words, bricks may be formed with substantially zero porosity. Moreover, an increased degree of surface hardness is imparted thereto.
  • the densified brick is also a mechanically stronger brick.
  • a cast and machined brick fractured at 3.8 tons, whilst a densified brick produced in accordance with this invention did not fracture until the load was increased to 5.5 tons.
  • bricks having a number of different upper and lower surface profiles may be formed with the apparatus described.
  • a mirror image of the brick of FIGURE 3 may be formed.
  • other surface profiles may be obtained by providing interchangeable punches and/ or by providing inserts for filling certain of the cavities in the die.
  • the finished brick must have virtually the same composition. This is not necessarily so in the case of a cast brick which has been machined, since if a disproportionate quantity of lead or antimony exists in the surface of the brick, this being removed by machining, the finished brick will have a different composition.
  • Apparatus for the cold pressing of lead bricks which comprises a die whose internal cross-section is constant throughout its length and corresponds to the desired crosssection of a lead brick, an upper male punch having a V section projection at its inner end and a lower female punch having a V section recess therein at its inner end, said female punch comprising a base part having an inner end wall normal to the axis of the die and at least two auxiliary parts each of right-angled triangle section, each said auxiliary part resting on said inner end wall of said base part, and screws securing each said auxiliary part to said base part to permit sideways movement of the auxiliary part as pressure is applied thereto during the pressing operation, the male punch having at least one transverse dimension which is slightly less than the corresponding dimension of the die to form spew gates along opposite sides of the male punch to permit excess lead to be expelled from the die.
  • the method of cold pressing a lead brick which comprises defining a die cavity whose cross-section is constant throughout its length, closing the lower end of the die by two punch surfaces which are inclined to one another to define a V section recess, and a further flat surface forming the base of the V section, placing in said die a lead blank of random shape, closing the upper end of the die by punch surfaces which are inclined to one another to define a V section projection, the outer ends of said upper punch surfaces being spaced from the inner walls of the die to provide spew gates to permit the expulsion of excess lead from the die, moving said upper punch surfaces downwardly to compress the lead blank under a pressure in excess of 20 tons per square inch, and permitting the inclined surfaces of the lower punch to move laterally and at the same time slide on said further flat surface to maintain an unbroken surface closing the lower end of the die and, after the lead has flowed to the internal shape of the die cavity, removing the upper punch surfaces and raising the lower punch surfaces to expel the shaped brick from the die cavity.
  • the method of forming a lead brick for use in building shields against nuclear radiation which comprises pressing a lead blank in the cold state in a closed die betwen a male punch and a female punch, the cavity of said die being defined by wall surfaces shaped to the required configuration of the finished brick, said pressing being carried out at a pressure in excess of twenty tons per square inch, causing the lead to assume the fluid state and to flow to the shape of said die cavity, said pressure being carried out until the porosity of the brick being formed is substantially eliminated and until the density of the lead is increased substantially to the maximum value and thereafter removing the brick from the die.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
US335911A 1960-01-23 1964-01-06 Production of lead shielding bricks Expired - Lifetime US3302442A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2537/60A GB905727A (en) 1960-01-23 1960-01-23 Improvements in or relating to the production of lead bricks

Publications (1)

Publication Number Publication Date
US3302442A true US3302442A (en) 1967-02-07

Family

ID=9741314

Family Applications (1)

Application Number Title Priority Date Filing Date
US335911A Expired - Lifetime US3302442A (en) 1960-01-23 1964-01-06 Production of lead shielding bricks

Country Status (4)

Country Link
US (1) US3302442A (xx)
CH (1) CH365606A (xx)
GB (1) GB905727A (xx)
NL (1) NL260374A (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115228958A (zh) * 2022-07-14 2022-10-25 山东源硕祥辐射防护工程有限公司 一种冷压成型式铅砖生产方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US125376A (en) * 1872-04-09 Improvement in dies for pressing bullets
US163656A (en) * 1875-05-25 Improvement in devices for swaging bullets
US1190696A (en) * 1913-10-11 1916-07-11 Arthur Wilzin Means for shaping spoon-bowls and the like.
US1234654A (en) * 1916-06-23 1917-07-24 Arthur C Gaynor Dir for making bullets and similar articles.
US1702278A (en) * 1928-05-18 1929-02-19 Simons Abraham Method of making seamless containers
US3034178A (en) * 1959-07-27 1962-05-15 Metallurgie Francaise Method of manufacturing parts of thin form by fritting

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US125376A (en) * 1872-04-09 Improvement in dies for pressing bullets
US163656A (en) * 1875-05-25 Improvement in devices for swaging bullets
US1190696A (en) * 1913-10-11 1916-07-11 Arthur Wilzin Means for shaping spoon-bowls and the like.
US1234654A (en) * 1916-06-23 1917-07-24 Arthur C Gaynor Dir for making bullets and similar articles.
US1702278A (en) * 1928-05-18 1929-02-19 Simons Abraham Method of making seamless containers
US3034178A (en) * 1959-07-27 1962-05-15 Metallurgie Francaise Method of manufacturing parts of thin form by fritting

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115228958A (zh) * 2022-07-14 2022-10-25 山东源硕祥辐射防护工程有限公司 一种冷压成型式铅砖生产方法

Also Published As

Publication number Publication date
CH365606A (fr) 1962-11-15
GB905727A (en) 1962-09-12
NL260374A (xx)

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