GB2047147A

GB2047147A - Manufacturing sockets for extremity prosthesis

Info

Publication number: GB2047147A
Application number: GB8008657A
Authority: GB
Original assignee: KHARKOV AVIAT I IM NE ZHUKOV; UKRAIN NII PROTEZIROVA PROTEZ
Current assignee: KHARKOV AVIAT I IM NE ZHUKOV; UKRAIN NII PROTEZIROVA PROTEZ
Priority date: 1979-04-06
Filing date: 1980-03-14
Publication date: 1980-11-26
Also published as: FR2452916A1; DE3012120C2; AT387515B; DE3012120A1; ATA142280A; FR2452916B1; GB2047147B

Abstract

A die cavity of the stump's size and shape is formed in a readily hardenable material. A hollow metal blank is placed in the cavity, the blank is filled with a liquid and impact load is applied to the liquid by a shot fired from a gas gun 5 thereby causing the blank to take the shape of the die. <IMAGE>

Description

SPECIFICATION Method of manufacturing sockets for extremity prosthesis, an individual die and a gas gun for carrying out the method and methods of manufacturing the individual die This invention relates to the manufacture of sockets for extremity prosthesis by forming a hollow metal socket blank in a die.

According to a first aspect of the invention there is provided a method of manufacturing a socket for extremity prosthesis by forming a hollow metal blank in a die, comprising the steps of making an individual die having a cavity of the stump's exact shape, placing the hollow metal blank in the cavity, filling the blank with a liquid and applying an impact load to the liquid by a shot fired from a gas gun thereby to cause the blank to take the shape of the die and form a socket of the stump's exact size and shape.

The invention also provides an individual die for use in carrying out the method, comprising a case having the form of a split drum mounted on a plate and filled with a quick-hardening material defining a cavity of the stump's exact shape.

One method of manufacturing the individual die comprises the step of filling the die case with a quick-hardening material, inserting into the quickhardening material the stump covered with a close fitting cover which has the same thickness as the hollow metal socket blank to be formed in the die, allowing the material to harden and then withdrawing the stump to leave a cavity in the hardened material having the exact shape of the stump.

An alternative method of manufacturing the individual die comprises the steps of filling the die case with a quick-hardening material and inserting into the quick-hardening material an envelope having an inner surface adapted to define the die cavity and formed to the exact shape of the stump, the envelope having been produced by winding a gypsum-impregnated band over the stump covered with a close fitting cover of the same thickness as the hollow metal socket blank to be formed in the die, and the envelope having been treated with a setting agent prior to the insertion into the quick-hardening material.

According to a further aspect of the invention there is provided a gas gun for use in carrying out the method referred to above comprising a vertically arranged combustion chamber supported on a frame and having an open end supporting coaxially a cylindrical extension, a pneumatic cylinder and a sleeve disposed on the extension, one end of the sleeve being provided with a piston arranged within the pneumatic cylinder and the other end having a shoulder with an inner diameter equal to or greater than that of the cylindrical extension, and a through slot for inserting a membrane to be supported by the shoulder and held against the end face of the cylindrical extension by the pneumatic cylinder.

Practicing of this invention provides for making prosthetic sockets of the exact size and shape of the stump thanks to the fact that the hollow metal blank is formed in die cavity which has been produced directly from the stump of a patient which completely eliminates manual adjustments of a ready made prosthetic socket.

Making of the individual hollow metal blanks in the form of solids of revolution and set of such solids, e.g. cones, cylinders, etc., that may be enclosed within the individual die cavity to the maximum, allow the scope of the prosthetic sockets to be widened to suit the stumps of various shapes and sizes without making resort to the utmost plastic strains of the socket material, thereby assuring the required strength and service life.

By making a conical or cylindrical blank of a developed length which exceeds that of a cone or cylinder enclosed within the die cavity makes it possible due to the extra material to manufacture the prosthetic sockets which have considerable variations of shapes and sizes without making resort to the utmost plastic strains of the blank material. This is due to the shaping where the material flows freely to the deformation zone rather than by stretching.

The effect of an impact load applied through a liquid, e.g. water, to the blank of a prosthetic socket by a shot fired from a gas gun permits of a uniform distribution of pressure on the blank being formed in the die cavity and makes it possible to manufacture the prosthetic sockets by the present method so that they may have various shapes and sizes faithfully copying the cavity produced directly from the stump of a patient and with a minimum expenditure of time and labour.

The gas gun for carrying out this method is a low cost and suitable system, which makes it possible to carry out the labour-consuming process of manufacturing prosthetic sockets in an automatic sequence and by mechanized means and simultaneously improving their quality and accuracy of size, and increasing efficiency of labour by a minimum expenditure of time for the making of a die and carrying out the process of forming the blank in the die. Accuracy to size in such prosthetic sockets is + 0.1 mm.

Now the invention will be more particularly described by way of example with reference to the accompanying drawings, wherein: Figure 1 is an individual die of the invention and the cavity thereof; Figure 2 is an individual die of the invention and a hollow metal blank; Figure 3 is the individual die and the hollow metal blank filled with a liquid; Figure 4 is an illustration of the forming of the blank in the die cavity; Figure 5 is an individual die of the invention and a split drum; Figure 6 is a plan view of the individual die of Figure 5; Figure 7 is an individual die filled with a readily hardenable material; Figure 8 is an illustration of the step of forming the die cavity; Figure 9 is an envelope removed from the stump; Figure 10 is an illustration of the step of forming the envelope;; Figure 11 is an illustration of the step of inserting the envelope into the readily hardenable material; Figure 12 is a hollow metal blank shaped as a cone; Figure 13 is a hollow metal blank shaped as a cylinder; Figure 14 is a hollow metal blank with its edges overlapped along the longitudinal joint; Figure 15 is a blank consisting of a series of cones; Figure 16 is a blank consisting of a series of cylinders; Figure 17 is a blank consisting of a cone and cylinder; Figure 18 is a gas gun of the invention.

The inventive method of manufacturing sockets for extremity prosthesis is practiced as follows.

First an individual die 1 (Figure 1) having a cavity 2 of the exact size and shape of the stump, is made.

Now placed into the die cavity (Figure 2) is a hollow metal blank 3 made as of aluminium alloy, stainless steel, etc. The blank 3 is filled with a liquid 4 (Figure 3). The liquid may be water and a glycerine in water emulsion, glycerine and other liquids which are inert to oxygen.

A transient load is applied to the liquid (Figure 4) by a shot fired from a gas gun 5. Pressure, produced in the liquid, is applied on the blank thereby shaping the same to the cavity 2 of the die 1.

The individual die (Figures 5, 6) may take the form of a split drum 6 placed on a plate 7, providing a hollow case filled with a readily hardenable material 8 defining a cavity 2 of the exact size and shape of the stump. A bolt and nut arrangement for the drum 6 is utilized as a connector. The readily hardenable material in the die may be gypsum, paraffin, a mixture of paraffin and stearin, organic resin, etc.

The individual die is manufactured as follows.

The case of the die 1 is filled with the readily hardenable material 8 (Figure 7). A close fitting cover 10 of an elastic material is put on a stump 9. The thickness of the cover is the same as that of the metal blank 3 of the prosthetic socket. The metal case of the die 1 is filled with a semiliquid gypsum.

The stump in the cover 10 (Figure 8) is dipped into the semiliquid gypsum.

Following the gypsum setting the individual die with the cavity 2 of the exact size and shape of the stump of a patient is ready (Figure 1) and the stump is removed from the cavity 2.

An alternative method of manufacturing an individual die consists in that the cavity 2 of the die 1 is made as an envelope 11/Figure 9/ by winding a gypsum-impregnated band 12 over the stump 9 covered with a close fitting cover 10/Figure 10/. The gypsum-impregnated band may be a cotton fabric.

After the band material has set, the envelope 11 is removed from the stump, dried until hard enough and a setting agent, such as paraffin, a mixture of paraffin and stearin, resins based on various substances, etc., is applied to form a layer thereof.

Following this step the envelope 11 is dipped into the readily hardenable material 8 in the case of the die 1/Figure 11/. After the material 8 has set the die is ready for the forming step.

The blanks for the prosthetic sockets are hollow solids of rotation that may be enclosed within the individual die/Figures 12, 13, for example a cone or a cylinder.

To produce prosthetic sockets of an intricate shape the hollow blank 3 is made to the development of a blank surrounding the stump, such blank as a cylinder or cone, which developed blank, being formed as a cone or cylinder, is placed into the cavity 2 of the die 1/Figure 14/. In doing this there is an extra material along the longitudinal joint, which extra material, if in excess of that required, is cut off and the blank is butt welded along the same joint.

If the prosthetic sockets are to have an intricate shape as well, the blank is made of a series of cones or cylinders and of a cone or a cylinder of unequal size, which element may be enclosed within the die cavity/Figures 15, 16, 17/.

The series of cones and/or cylinders is put into the die cavity and shaped as above starting frm the lower cone or cylinder.

Then the next cone or cylinder is shaped in the manner described.

After the series of cones and/or cylinders has been shaped, the cones and/or cylinders are removed from the die cavity and butt welded together.

Such is the procedure of manufacturing an elongated prosthetic socket of an intricate shape which is an exact replica of the size and shape of the stump of a patient.

The gas gun (Figure 18) for carrying out the inventive method is supported on a frame 13 and comprises a combustion chamber 14 with pipes 15 and 16forfeeding and igniting of a gaseous mixture respectively.

On an open end of the combustion chamber 14 there is a cylindrical extension 17 which coaxially supports a sleeve 18 having a shoulder 19 the inner diameter of which is equal to or greater than that of the extension 17.

On the sleeve 18 between the shoulder 19 and the sleeve proper there is a horizontally disposed through slot 20 for securing a sealing membrane 21 thereto. The sleeve 18 at the other end thereof is rigidly connected to a piston 22 which is disposed within a pneumatic cylinder 23 secured to the extension 17. An annular disk 24 is mounted on the sleeve 18 for vertical movement toward the die under the action of two pneumatic cylinders 25 installed by means of brackets 26.

The frame 13 is equipped with a vertically movable table 27 for transferring the die 1 with the blank 3 to the moulding zone.

The above apparatus operates as follows.

First the gas gun 4 is prepared for operation. The sealing membrane 21 is inserted into the through slot 20 and is forced against the end face of the cylindrical extension 17 by the pneumatic cylinder 23 through the sleeve 18, thereby forming a sealed space within the combustion chamber 14, a feed of combustible gaseous mixture, for example methane and oxygen, is delivered through the fittings 15 into the combustion chamber 14 until the working pressure is reached. The gas gun is ready for operation.

The die 1 with the blank 3 having the cavity filled with liquid is put on the vertically movable table 27. The vertically movable table 27 carries the die and the blank until the end of the gas gun with the membrane 21 is in the cavity of the blank 3. Next the pneumatic cylinders 25 lower the disk 24 toward the die 1. The mixture within the combustion products enter the liquid 4 and produce a transient load therein, which load in turn shapes the blank 3 in the cavity 2 of the die 1. After the shaping step the table 27 lowers the die 1 to its lowermost position. The die 1 is removed from the table 27. The prosthetic socket is removed from the die 1. The disk 24 returns to its initial position, the cylinder 25 is pressed back, and the fragments of the membrane 21 are removed. The apparatus is ready for the next cycle.

Claims

1. A method of manufacturing a socket for extremity prosthesis by forming a hollow metal blank in a die, comprising the steps of making an individual die having a cavity of the stump's exact shape, placing the hollow metal blank in the cavity, filling the blank with a liquid and applying an impact load to the liquid by a shot fired from a gas gun thereby to cause the blank to take the shape of the die and form a socket of the stump's exact size and shape.

2. An individual die for use in carrying out the method of claim 1, comprising a case having the form of a split drum mounted on a plate and filled with a quick-hardening material defining a cavity of the stump's exact shape.

3. A method of maufacturing an individual die as claimed in claim 2, comprising the steps of filling the die case with a quick-hardening material, inserting into the quick-hardening material the stump covered with a close fitting cover which has the same thickness as the hollow metal socket blank to be formed in the die, allowing the material to harden and then withdrawing the stump to leave a cavity in the hardened material having the exact shape of the stump.

4. A method of manufacturing an individual die as claimed in claim 2, comprising the steps of filling the die case wih a quick-hardening material and inserting into the quick-hardening material an envelope having an inner surface adapted to define the die cavity and formed to the exact shape of the stump, the envelope having been produced by winding a gypsum-impregnated band over the stump covered wih a close fitting cover of the same thickness as the hollow metal socket blank to be formed in the die, and the envelope having been treated with a setting agent prior to the insertion into the quick-hardening material.

5. A method as set forth in claim 1 in which the hollow metal blank placed in the cavity, is a solid of revolution receivable within the cavity.

6. A method as set forth in claim 5, in which the solid of revolution has longitudinal edges which are overlapped, the amount of the overlap being adjusted to adjust the size of the solid of revolution to the cavity.

7. A method as set forth in claim 1, in which the hollow metal blank placed in the cavity is formed by a plurality of solids of revolution arranged to be received within the cavity.

8. A method as set forth in claim 7, in which the hollow metal blank comprises a series of cones of unequal tapers.

9. A method as set forth in claim 7, in which the hollow metal blank comprises a series of cylinders of unequal diameters.

10. A method as set forth in claim 7, in which the hollow metal blank comprises a cone and a cylinder.

11. A gas gun for use in carrying out the method of claim 1, comprising a vertically arranged combustion chamber supported on a frame and having an open end supporting coaxially a cylindrical extension, a pneumatic cylinder and a sleeve disposed on the extension, one end of the sleeve being provided with a piston arranged within the pneumatic cylinder and the other end having a shoulder with an inner diameter equal to or greater than that of the cylindrical extension, and a through slot for inserting a membrane to be supported by the shoulder and held against the end face of the cylindrical extension by the pneumatic cylinder.

12. A gas gun according to claim 11, wherein an annular disk is attached to the cylindrical extension for raising and lowering the open end thereof.

13. A method of manufacturing sockets for extremity prosthesis as claimed in claim 1 and substantially as herein described with reference to the drawings.

14. An individual die as claimed in claim 2 and substantially as herein described with reference to Figures 5 to 8 or 9 to 11 of the accompanying drawings.

15. A method of manufacturing an individual die, as claimed in claims 3 and 4 and substantially as herein described with reference to Figures 5 to 8 or 9 or 11 of the accompanying drawings.

16. A gas gun substantially as herein described with reference to Figure 18 of the accompanying drawings.