US 2336026 A
Description (OCR text may contain errors)
Dec. 7, 1943.
R. MILLENAAR 2,336,026
X-RAY GRID AND THE LIKE Original Filed Feb. 8. 1938 INVENTOR. [fie/Men ML LEN/141g.
Patented Dec. 7, 1943 X-RAY GRID AND THE LIKE Richard Millenaar, Oak Park, Ill., assignor to The Richardson Company, Lockland, Ohio, a
corporation of Ohio Original application February 8, 1938, Serial No. 189,422. Divided and this application May 23,
1940, Serial No. 336.812
This application is a division of my application Serial No. 189,422, filed February 8, 1938, for Method and apparatus for the manufacture of X-ray grids and kindred devices.
I shall describe my invention in connection with the manufacture of what are known as X-ray grids, it being understood that the preferred method and apparatus are those set forth in the copending application and are applicable to the manufacture of other articles presenting the same or similar problems.
In the taking of X-ray photographs, as is well known, an X-ray tube is located upon one side of the body to be photographed and the sensitized photographic film is located upon the other. The rays sent out by the X-ray tube travel as from a point source, and give on the photographic plate what may be termed a shadow image. While X-ray photographs have been made in this way with satisfaction for a large are caused to impinge upon the grid in a direction very nearly parallel to the plane of the said layers therein. X-ray grids have heretofore been manufactured of alternate thin laminations of lead foil or the like, and laminations of paper, the said laminations, on edge, being interposed between cover sheets of Celluloid or similar composition. Such grids, usually of foreign manufacture, have so far as is known been assembled by hand in a very laborious fashion, and are very costly.
The fundamental object of my invention is the provision of a means and method for the manufacture of X-ray grids or of similar products which are inexpensive and rapid while giving accurate and satisfactory results. The problem,
in a sense, is one of the machine manufacture of structures of this class; and ancillary objects of my invention will'be apparent in the ensuing discussion where the various problems are'set forth.
By way of example, it is possible to assemble laminae of lead foil and the like, and laminae of paper or other fabric, saturated in an incompletely cured synthetic resin (e. g. a resin varnish consisting of the incompletely polymerized resin dissolved in a solvent such as water or alcohol). Before assembling, the saturated laminae are dried. In this way a block can be built up in which the layers are accurately formed and accurately spaced. If it were possible to shave this block into layers transversely of the planes of the laminae, theoretically quite excellent X-ray grids could be formed and there would be no essential limitation on their size. Such blocks can easily be produced, but it has not been found possible by any means or procedure of which I am aware to shave these blocks into grids. In any procedure by which the block is cut into layers, the relatively soft foil occurring between other laminae is mashed and distorted, and is peened over the edges of adjacent laminae so as to give a structure in which the grid form is interrupted and non-uniform. Attempts to make X-ray grids in this fashion have, therefore, uniformly failed.
In the practice of my invention I preferably produce X-ray grids or like articles by the rapid machine production and assembly of the individual laminae, which are positioned between protective covering sheets in ways which I shall hereinafter set forth. Fundamental objects of my invention are the production of a new type of X-ray grid, which is excellent in uniformity and performance, and is much cheaper in cost. Moreover it is an object of my invention to provide an X-ray grid of such construction that it may readily and cheaply be formed by machinery as distinguished from hand labor.
The several objects of my invention I accomplish by that method and in that structure and arrangement of parts of which I shall now set forth a particular exemplary embodiment. Reference is now made to the drawing wherein:
The single figure is an enlarged side elevation of an X-ray grid produced on my machine.
For the laminae, I first make composite sheets by taking one or two layers of paper or the like, saturated in synthetic resin, a layer of lead foil and one or two additional layers of saturated stock, the lead foil being preferably sandwiched between the other layers. This composite sheet is pressed and cured in the ordinary way for laminated resinous products. The laminae for the X-ray grid are preferably formed by a diecutting operation of such nature that the die simultaneously cuts both longitudinal edges of the laminations. The laminations cut in this way may be assembled as desired, or may be pushed on edge, whereby they are accurately assembled together in the desired relationship. They may be assembled between the two cover sheets. All of these cutting and assembly operations are capable of being performed by machinery. By continued operations of the machine and the feeding to it of composite sheets, as hereinabove explained, the body of assembled laminae between the two cover sheets is produced. There is no essential limitation upon the length of X-ray grids which may be made in this way, nor is there any limitation on the width of the grid other than the maximum width for which' the machine is constructed. The two cover sheets are pre-v viously coated with a thermoplastic cement which is hard at normal temperatures, but which, when heated, will fuse and bind the composite structure together. By the die-cutting operation to which I have referred, spalling and peening of the lead foil layer is prevented; and I keep my dies clean by means of air or other fluid, so that shavings or other pieces of the lead foil will not be incorporated in the grid structure.
I will first describe an exemplary grid as illustrated in the figure. This grid comprises interspaced cover sheets 4 and 5. Between the sheets there are laminations indicated generally at 6. Each lamination comprises a layer of lead or the like I sandwiched between layers 8 and 9 of material transparent to X-rays. In an exemplary embodiment, the over-all thickness of the article may be from .120 to .125 inch, whereas the space between the two cover sheets 4 and may be onesixteenth of an inch. The total thickness of each lamination may be .020 inch. Each lamination may contain a layer of lead .001 inch in thickness, the remainder of the thickness of the lami' nation being paper saturated in resin. With the dimensions just given, there will be fifty punchings or laminations per linear inch of the product. It will be understood that the dimensions which I have given are for the sake of a complete exemplary disclosure and do not constitute limitations, since these may be varied as desired. I have hereinabove discussed the matter of limitations as to size. With my particular machine I am currently making X-ray grids 17 inches by 20 inches; but larger or smaller ones can readily be made in accordance with my teachings.
In producing the stock for the laminations I ordinarily take two sheets of paper which have been saturated in a resin, as hereinabove set forth. Any of the synthetic resins may be used. Ordinarily I use a phenol formaldehyde resin of the Bakelite type. On these two layers I lay a layer of lead foil, and over this assemble two more layers of the saturated paper. The whole is placed between the usual polished plates in a press and the laminated structure is cured under heat and pressure, as is usual in synthetic resin practice. I do not desire, however, to be limited to laminae containing synthetic resin, since it will be perfectly apparent as the description proceeds that there are many ways of making the composite sheet for the laminations, and that material which is opaque to X-rays and material transparent to X-rays may be adhered together in a wide variety of ways for the uses of this invention.
Previous to assembling the cut laminae between the cover sheets I have coated the surfaces of the cover sheets with a thermoplastic cement. I am not limited to any particular material for the cover sheets, and may use any desired fabric web or sheet including, but without limitation, Celluloid or any molded clear plastic.
However, I have been using in practice cover sheets made up of a series of laminations of paper saturated in an incompletely polymerized resin, for example, Bakelite, or one of the urea resins, and pressed and cured in the usual way. The thermoplastic cement which I have been employing is a so-called Bakelite cement or other similar product available on the market and believed to consist largely of a rubber resin dissolved in a suitable volatile organic solvent. Such a cement dries hard, but retains, for very long periods at heat. The nature of the thermoplastic cement is, however, not a limitation on my invention.
The cured resinous laminated sheet stock, including the lead or its equivalent, is cut apart accurately into individual laminae. The stiffness of the cured resinous product is such that these laminae are self-sustaining and are capable of being stacked side by side and on edge. As indicated, the cutting is preferably done by means of dies which shear both edges of a grid lamina at the same time, and the dies may be and pref erably are so located that an assembly of the cut laminae in face to face relationship is madeby the dies, each die operation adding one lamina to the assembly. By positioning the cover sheets with reference to the assembly so made, the assembly may be caused to grow between the cover sheets to whatever extent is desired. During the fusing of the thermoplastic material on the cover sheets, whereby the structure is bound into an integral mass, I prefer to confine the laminae between them under resilient sidewise pressure, also exerting pressure on the cover sheets during the application of heat. When the desired assembly of laminations has been made between the cover sheets 4 and 5, I apply heat to one or both sides of the assembly so as to fuse the ther-; moplastic material and bind the whole structure into one integral mass.
When the grid structure has been built up-in the way described, and is cooled and solid, the edges are trimmed as may be desired. The whole may be placed in a suitable frame, or may be given a metal binding. 7
Modifications may be made in my invention without departing from the spirit of it.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
1. An X-ray grid or like structure comprising sidewise disposed and interspaced cover sheets and laminae disposed therebetween in sidewise juxtaposed, substantially non-adhering relationship, the plane of said laminae being substantially normal to the plane of said cover sheets and said laminae being in adhering relationship at their edges to said cover sheets, said laminae each consisting of a layer of metal sandwiched between and in adhering relationship to layers of stiff sheet material of non-metallic character.
2. An X-ray grid or like structure comprising sidewise disposed and interspaced cover sheets and laminae sufficiently stiff to be self-sustaining disposed therebetween in sidewise juxtaposed, substantially non-adhering relationship, the plane of said laminae being substantially normal to the plane of said cover sheets, each said laminae consisting of a layer of metal sandwiched between and in adhering relationship to layers of sheet material of non-metallic character, said' cover sheets being coated within with an adhesive, and said adhesive causing said laminations to adhere to said cover sheets primarily at theareas ,of contact between said cover sheets and said laminations.
3. An X-ray grid or like structure comprising sidewise disposed and interspaced cover sheets and laminae disposed therebetween in sidewise juxtaposed relationship to said cover sheets, the plane of said laminae being substantially normal to the plane of said cover sheets, said laminae each consisting of a cured resinous product comprising a metallic sheet interleaved between webs of non-metallic substance saturated with synthetic resin, and having sufficient combined rigidity to provide a lamina which is self-sustaining without face-to-face attachment to adjacent laminae.
4. An X-ray grid or like structure comprising sidewise disposed and interspaced cover sheets and laminae disposed therebetween in sidewise juxtaposed relationship to said cover sheets, the plane of said laminae being substantially normal to the plane of said cover sheets, said laminae each consisting of a cured resinous product comprising a metallic sheet interleaved between webs of non-metallic substance saturated with synthetic resin, and having sufficient combined rigidity to provide a lamina which is self-sustaining without face-to-face attachment to adjacent laminae, said cover sheets consisting of non-metallic webs saturated with synthetic resin and pressed and cured.
5. An X-ray grid or like structure comprising outer cover sheets of pressed and cured resin saturated laminae, and between said sheets, selfsustaining laminae arranged in side by side relationship and on edge with respect to said cover sheets, each said laminae consisting of at least one layer of resin saturated material in cured condition and a layer of metal in adhering union therewith, said laminae being adhered to said cover sheets substantially wholly at the edges of said laminae.
6. An X-ray grid or like structure comprising outer cover sheets of pressed and cured resin saturated laminae, and between said sheets, selfsustaining laminae arranged in side by side relationship and on edge with respect to said cover sheets, said laminae consisting of at least one layer of resin saturated material in cured condition and a layer of metal in adhering union therewith, said cover sheets having a coating of thermoplastic adhesive on their sides next said laminae, said thermoplastic adhesive serving to secure said cover sheets and said assembled laminae in assembled relationship.
7. An X-ray grid comprising upper and lower outer covering sheets of pressed and cured resin saturated sheet stock, and between said sheets laminae arranged in juxtaposed relationship and on edge with respect to said cover sheets, said laminae comprising at least one layer of resin saturated sheet material pressed and cured against a layer of X-ray impervious metal foil, said cover sheets being coated with a thermoplastic adhesive, said laminae having clean, cut edges Without substantial displacement of the metal foil such as may be formed by the simultaneous punching of both edges thereof and arranged between said cover sheets, the whole forming an integral structure through an adhesive bond of the edges of said laminae to said ,cover sheets by means of said coating of thermoplastic substance.