MXPA99002846A - Method and apparatus for making an article from a formable material - Google Patents

Abstract

A method and apparatus are described for making an article such as the body of a needleless injector capsule, from a formable material, such as glass, the article having a cavity communicating with the exterior via an orifice. A blank (1a) having an open end is mounted on a first forming tool, and the open end is engaged by a second forming tool (22) while an end region of the blank (1a) adjacent the open end is in a condition to permit it to be formed. One of the tools (7a) has a pin (21) extending therefrom, and when the tools are brought together to form the end region into the desired shape the pin (21) defines the orifice.

Description

METHOD AND APPARATUS TO MAKE AN ARTICLE FROM A FORMABLE MATERIAL The invention is in the field of needleless injectors that use a capsule to hold a liquid drug to be injected, and hypodermic syringe bodies of the needle type. Needleless injectors are used as an alternative to conventional hypodermic injectors to deliver medications through the skin of a patient into the underlying tissues. These injectors use a high-pressure piston pump to distribute a liquid drug injection with sufficient force to penetrate the skin, and then deposit the drug in the dermal, subcutaneous, or muscular tissues. The drug is distributed from a cylindrical chamber, which has a thin hole at one end through which the drug is discharged. A piston is located slidably and sealed in the chamber, and the drug is within the space between the hole and piston. To make an injection, the hole is placed on the skin, and when operating a release mechanism, the piston acts by a force that can be derived from a spring, gas or chemical reaction under pressure. The capsule can be filled by the user, or it can be filled beforehand and pre-assembled to an activator. In the latter case in particular, the materials from which the capsule and piston are constructed must be inserted into the drug, that is, they must not react with the drug chemically, physically, and must not contain dangerous extracts that may contaminate the drug. drug. The choice of materials is small: borosilicate glass is the favorite capsule material when drugs must be stored for more than a few hours. If an alternative material is selected for the capsule, many years of testing should be done to validate that material, while borosilicate glass has a known compatibility with most drugs. During the injection, the pressure generated in the capsule is at least 100 bar, and it is preferred, in order to avoid runoff during the injection, that the orifice be integral with the cylindrical chamber. In addition, the shape and dimension of the hole is critical to the operation of the injection, and for results that can be repeated these aspects should be made to close tolerances. However, glass is a difficult material to mold and maintain such close tolerances over many millions of components. A traditional method is to work the hot and soft end of a glass tube on a foam, and by applying a configuration wheel or paddle, to close one end in a mandrel to form the hole. This is a relatively crude method, and the only parameters that can be precisely controlled are the diameter of the hole and the diameter of the surrounding glass: the length and profile of the orifice entrance are allowed to change since the process only forms the outside of the tube and the diameter of the hole. An alternative process is to mold, so a hot spit of molten glass is molded into a die. This process is suitable for large components, but the needleless injection capsules are larger than the 1 ml capacity, and said small glass spittle loses its heat quickly and is difficult to mold. Also the surface finish inside a molded tube is not smooth enough for this application, nor is the parallel of the hole. The extracted tube, which has an excellent surface finish and shape, is the preferred starting material, but current working methods, as described, do not provide control of internal and external dimensions. Conventional glass hypodermic syringes are made in automatic foams from glass when working heat-softened tube, as described above. The inexpensive disposable glass syringes are usually made with the hollow needle stuck in a precisely formed hole in one end of the syringe body. The manufacturing process is relatively primitive, with low production speeds and high rejection speeds. The present invention seeks to overcome the disadvantages of current methods for forming glass tubes by providing a means for forming the hole, and the internal and external percieves of a needleless injection capsule or hypodermic jerkin body, which means has excellent ability of repetition and is capable of producing at high speed.

According to the invention, a method is provided for making an article from a formable material, the article having a cavity communicating with the outside by means of a hole, wherein a template having an open end is mounted on a first forming tool, and the open end is engaged by a second forming tool while an end region of the template adjacent said open end is in a condition to allow it to form, one of said tools having a pin that is extends from it, and said tool and the other tool are joined to form said in a desired shape, with the pin that defines The invention further provides an apparatus for making an article from a formable material, the article having a cavity communicating with the outside by means of a hole, comprising a first forming tool for receiving an open template at the ends, and a second forming tool for coupling an end region of the template adjacent to the open end thereof to form it, one of said tools having a pin extending therefrom, the tools are arranged so that when they are joined to forming said end region in a desired shape the pin defines said hole.

The pin can be in any of the training tools, although in the modalities described below it is preferably in the first training tool. In a preferred embodiment of the invention, a glass tube, cut to length, is placed in a mandrel having a profile in which the glass can be formed. The mandrel has a pin at its end to form the hole. The glass rotates and heats up at the end that is going to form. When it is at the optimum formation consistency, a forming tool having a profile to which the exterior of the tube is to be formed, is applied to the outside of the glass tube and presses the softened glass into the mat and pin.

Immediately before the formation, the rotation of the glass tube is interrupted; alternatively, the external forming tool rotates at the same speed as the tube, so that there is no relative movement between the tube and the external forming tool. A detailed description of the invention will now be made with reference to the accompanying drawings, in which: Figure 1 shows a central line section through a typical glass capsule, assembled at the tip of an activator or power source; Figure 2 shows a glass tube placed on a mandrel, with adjacent external forming tool; Figure 3 illustrates the shape of the forming tools in position having the pressed glass in the required shape; Figures 4 and 5 show modified forming methods that will accommodate wide tolerance glass tube; Figure 6 shows a hypodermic syringe body; Figures 7a and 7b show another modified method for forming a capsule; and Figures 8a and 8b show still another modified method for forming a capsule. Referring first to Fig. 1, capsule 2 is a cylinder containing drug 2, and a piston 3 in contact with drug 2. Capsule 1 is retained at tip 4 of a needleless injection activator when retaining the cover 5 that is in the shoulder 8 of the capsule 1. The lid 5 can be retained by 1 0 threads, fastening means or other suitable device. The discharge end of the inside of the capsule 1 is characterized by a frusto-conical shape 7 leading to the orifice 6. When the injector is operated, a ram 9 deviated in the direction Y is released in order to couple and drive the piston 3 for download drug 2 through hole 6. The ratio of length to hole diameter should be as short as possible, and it is desired that this should not be more than 2: 1. This relationship has a significant effect on the flow resistance of the orifice: very high and the orifice looks like a tube with a corresponding increase in flow resistance. Typically, the diameter of the hole can be within the range of 0.1mm to 0.5mm, with corresponding lengths within the range of 0.2mm to 1.0mm.

Upon injection, the face 1 1 of the retainer 5 is pressed lightly on the skin of the patient, and the area of the face 11 provides sufficient support to prevent the injection capsule assembly from being immersed in the tissues. If the face 12 is supported or slightly behind the face 11, the hole is in very light contact with the skin, and an intradermal injection will result; a firm contact, that is, the face 12 emerges slightly from the face 1 1, will result in a subcutaneous injection; and if the face 12 comes out considerably from the face 11 thus displacing and compressing the adipose tissue, then the injection can be intramuscular. Of course, this is a generalization, since other factors such as the pressure and size of the hole can be adjusted to achieve the required injection characteristics. However, the relationship of the face of the capsule and the face of the retainer can be controlled to achieve high quality repeated injections.

The purpose of the frusto-conical shape 7 joining the cylindrical section of the capsule 1 to the hole 6 is to reduce turbulent energy losses as the drug is forced into the hole 6, and also to minimize the stresses during injection. of the glass walls of the capsule 1 since the cylindrical hole is reduced to the hole 6.

The above description covers the essential design requirements of a needleless injection capsule; there may be small variations but the vast majority of injectors use a capsule that has a shape similar to the one described. Referring now to Figure 2, the material for the capsule 1 is a length of glass tube 1 a, which is located on the mandrel 20 and rests in the tube holder 23. The rod 20 has a frusto-conical shape 7a , which ends in a pin 21. Located centrally above the mandrel 20 is a forming tool 22, which has a forming surface 27. A hole 24 in the forming tool 22 is a closed space fit relative to the pin 21. The forming process begins by heating the tube 1 a in the area of the frusto-conical section 7a of the mandrel 20 to a temperature sufficient to soften the glass. Preferably, at least the mandrel 20 rotates, (and more preferably, the tube holder 23 and mandrel 20 rotate in unison, ie, at the same speed and in the same direction), together with the glass tube 1 to , during heating, so that the temperature of the glass is distributed evenly. Alternatively, the parts may remain stationary, the glass being heated by a ring furnace. When the optimum temperature is reached, the forming tool 22 is pressed into the softened glass as shown in Figure 3, and thus forms the glass tube 1 a to form the capsule 1. This is done with the support 23 and mandrel that rotate together in unison, or both stationary. The lengths of the hole 6 and other aspects are controlled by the face 26 of the forming tool 22 which abuts the face 25 of the tube support 23, but other interrupting means can also be effective. The process described and illustrated by figures 2 and 3 is idealized and would require an exact volume of glass tube to be presented to the forming tool. In practice, the dimensional tolerances of the glass tube are quite large, and even if a precise hole tube is specified, the variation in wall thickness results in a wide variation in external diameter. Figure 4 shows a method to overcome this problem. The forming tool 22a has a hole 24a that is substantially larger in cross section than the corresponding pin 21 a. This pin is shorter than the pin shown in Figure 2. In the illustration, hole 24 is frusto-conical, and has a cross section substantially larger than hole 21 at least for that length of the hole over which the pin is extended. In other words, there is a substantial space between the pin and the surface that define the hole. The glass tube is cut so that the volume is slightly larger than what is required for the finished capsule, and during formation, any excess material is formed on the hole 24a to form a mass 40, so that closes the hole formed by the pin 21 a. After removing the tube formed from the mandrel and tube holder, the mass 40 is cut into X-X and the cut face is flame-polished to remove the sharp edges and to soften any hard surface. If necessary, after cutting, the face can be ground before polishing with flame. Figure 5 shows another method for dealing with excess material. Again, the volume of the glass tube is slightly more than the finished capsule, and during formation, excess glass is allowed to spread on the forming tool to make an edge 50, the length Z of which may vary in accordance with the amount of excess glass. This method has the additional advantage that the diameter of the edge 50 is controlled, regardless of the thickness tolerance of the wall. It is important that the hole is formed without any "flash" of glass, and although Figures 3 and 5 show the pin 21 in the hole 24, the annular space between the pin and the hole must be very small to prevent the ingress of glass melt that would form a thin skin or "flash" over the hole 6. As a result, the alignment of the forming tool and mandrel is critical in Figures 3 and 5 to ensure that the pin 21 enters the hole 24 without bending or binding . This requires precise and expensive tools. Figures 7a and 7b show a method for preventing flash formation around the hole without the need for very precise tool alignment. The plunger 60 is a sliding fit within the forming tool 22b and a compression spring 64 is located on the plunger 64 which bears a collar 63 fixed thereto. The total allowed sliding motion is controlled by the faces of the collar 63 and bearing faces 65 and 67 within a cavity 66 in the forming tool 22b. The mandrel 20b carries a pin 21 b having a flat distal face 62, and the plunger 60 has a flat distal face 61. When the glass is formed, substantially as already described, the faces 61 and 62 cooperate to form an airtight "closure" to prevent the molten glass from forming a thin skin on the end of the hole in the capsule. The force of the closure is determined by the spring 64. Figures 8a and 8b show a similar arrangement, but in this case the pin 21 c is spring loaded by a compression spring 64c and slides in the mandrel 20c. When the forming tool 22c and the mandrel 20c join to form the glass, a face 70 of the pin 21 c cooperates with a face 71 of the forming tool 22c to form a seal. The above methods for forming the glass tube can be applied with equal efficiency to the production of glass syringes, as shown in Figure 6. In this case, the diameter of the hole 100 may be required to be controlled, to accept a needle hollow: the needle can be attached to the glass with a minimum thickness of adhesive. Alternatively, the frusto-conical tip 200 may be formed to accept a so-called Luer adjustment needle, ie, a needle with an adapter having an internal taper of cooperation by which the needle can be frictionally retained at the tip of the needle. syringe. The method for forming tube to make hypodermic needle-less syringes and capsules can be applied to materials other than glass where conventional forming methods are inappropriate.

Claims (1)

1. CLAIMS 1 .- A method to make an article from a formable material, by using a training apparatus that has an internal training tool and an external training tool, the article having a cavity that communicates with the outside by means of a hole, wherein a template having an open end is mounted on the internal forming tool, and the open end is engaged by the external forming tool while an end region of the template adjacent said open end is in a condition for allowing it to be formed, one of said tools having a pin extending therefrom, and said tools are joined to form said end region in a desired shape, wherein the internal surface of said end region is molded to the adjacent surface of the internal training tool, with the pin that defines said hole, where the pin in said one of the tools is received parci ally, during forming, in a hole provided in the other of said tools, there being a substantial tolerance between the pin and the surface defining the hole, to allow the material from the template to expand in tolerance to a controlled degree, and thus closing the end of said hole during formation, the hole closing the material being removed after forming. 2. - A method for making an article from a formable material, by using a training apparatus having an internal training tool and an external training tool, the article having a cavity communicating with the outside by means of a orifice, wherein a template having an open end is mounted on the internal forming tool, and the open end is engaged by the external forming tool while an end region of the template adjacent said open end is in a condition to allow which is formed, one of said tools having a pin extending therefrom, and said tools are joined to form said end region in a desired shape, wherein the inner surface of said end region is molded to the adjacent surface of the internal training tool, with the pin that defines said hole, the external training tool that has a cavity in the same ma, which looks at the internal training tool, with a cross section larger than the template, so that during the formation any excess material can be spread laterally outward to a degree allowed by said cavity. 3. A method according to claim 2, wherein the template is mounted on a tube holder with a space between them. 4. A method according to claim 2 or 3, wherein the pin has a length equal to the desired length of said hole and a distant surface, and the other tool where the pin is not mounted, has a plunger with a distal face which, prior to forming, looks at the distal face of the pin at a distance therefrom, and where during the formation said distal face of the pin and said distal face of the plunger meet in contact with each other. 5. A method according to claim 4, wherein said plunger is loaded with spring, and the pin produces movement of the plunger against the spring load during molding. 6. A method according to claim 4 or 5, wherein the degree of movement of the plunger is controlled by opposite faces that are formed therein and that are coupled, in use, with bearing faces formed in said other tool. 7. A method according to claim 2 or 3, wherein the pin is movably mounted on the forming tool for movement towards and away from the other forming tool, and since the tools are joined during molding the distal end of the pin first engages the other forming tool and then moves into said forming tool by said other forming tool. 8. A method according to claim 7, wherein the pin is deflected by a means of deflection towards said other forming tool, said coupling with said other forming tool that produces movement against the force of the deflection means. 9. A method according to claim 8, wherein said biasing means is a compression spring. 10. A method according to any preceding claim, wherein the pin is in the internal training tool. 1 - A method according to any preceding claim, wherein the tools do not rotate during molding. 12. A method according to any of claims 1 to 10, wherein the tools rotate in unison during molding. 13. A method according to any preceding claim, wherein said article is a body for a capsule adapted to be used in a needleless injector. 14. A method according to any of claims 1 to 12, wherein said article is a syringe body. 15. A method according to any of the preceding claims, wherein the formable material is glass. 16. - A method according to any preceding claim, wherein the end region of the template joins in its condition to allow it to form, by heating. 17. - A method according to claim 16, wherein the internal training tool rotates during the heating of the template. 18. A method according to claim 16, wherein the internal training tool does not rotate during the heating of the template. 19. A method for making an article from a formable material, the article having a cavity communicating with the outside by means of a hole, wherein a template having an open end is mounted on a first forming tool , and the open end is engaged by a second forming tool while an end region of the template adjacent said open end is in a condition to allow it to form, the first forming tool having a pin extending therefrom, and said tool and the other of said tools are joined to form said end region in a desired shape, with the pin defining said hole, wherein the pin has a length equal to the desired length of said hole and a distant surface, and the other tool has a piston with a distant face that, before forming, looks at the distant face of the pin at a distance from it, and where they last the formation, said face distant from the pin and said distal face of the plunger come together in contact with each other. 20. - An apparatus for making an article from a formable material, by using a training apparatus having an internal training tool and an external training tool, the article having a cavity communicating with the outside by means of a hole , wherein a template having an open end is mounted on the internal training tool, and the open end is coupled by the external training tool while an end region of the template adjacent said open end is in a condition to allow one of said tools having a pin extending therefrom is formed, and said tools are joined to form said end region in a desired shape, wherein the inner surface of said end region is molded to the adjacent surface of the internal training tool, with the pin that defines said hole, where the pin in said one of the tools is partially received during the formation, in a hole provided in the other of said tools, there being a substantial tolerance between the pin and the surface defining the hole, to allow the material from the template to expand in tolerance to a controlled degree. 21 .- An apparatus for making an article from a formable material, by using a training apparatus that has an internal training tool and an external training tool, the article having a cavity that communicates with the outside by means of a hole, wherein a template having an open end is mounted on the internal forming tool, and the open end is engaged by the external forming tool while an end region of the template adjacent said open end is in a condition for allowing it to be formed, one of said tools having a pin extending therefrom, and said tools are joined to form said end region in a desired shape, wherein the internal surface of said end region is molded to the adjacent surface of the internal training tool, with the pin that defines said hole, the external training tool that has a cavity in the isma, which looks at the internal training tool, cross section larger than the template, so that during the training can be spread any excess material laterally outward to a degree allowed by said cavity. 22. An apparatus according to claim 21, where a tube holder is provided for the template that is to be mounted in a space between them. 23. An apparatus according to claim 21 or 22, wherein the pin has a length equal to the desired length of said hole and a distant surface, and the other tool where the pin is not mounted, has a plunger with a distant face which, prior to forming, looks at the distal face of the pin at a distance therefrom, and where during the formation said distant face of the pin and said distal face of the plunger meet in contact with each other. 24. An apparatus according to claim 23, wherein said plunger is spring-loaded, and the pin produces movement of the plunger against the spring load during molding. 25. An apparatus according to claim 23 or 24, wherein the degree of movement of the plunger is controlled by opposite faces that are formed therein and that are coupled, in use, with bearing faces formed in said other tool. 26. An apparatus according to claim 21 or 22, wherein the pin is movably mounted on the forming tool for movement toward and away from the other forming tool, and since the tools are joined during molding the distal end of the pin first engages the other forming tool and then moves into said forming tool by said other forming tool. 27. An apparatus according to claim 26, wherein the pin is deflected by a means of deflection towards said other forming tool, said coupling with said other forming tool that produces movement against the force of the deflection means. 28. An apparatus according to claim 27, wherein said biasing means is a compression spring. 29. - An apparatus according to any of the preceding claims, wherein the pin is in the internal training tool. 30. An apparatus according to any of claims 20 to 29, comprising means for heating said end region of the template to carry it in a condition to allow it to be molded. 31. An apparatus according to any of claims 20 to 30, comprising means for rotating the internal training tool. 32. An apparatus according to claim 31, comprising means for rotating the external training tool. 33.- An apparatus for making an article from a formable material, the article having a cavity communicating with the outside by means of a hole, comprising a first forming tool for receiving an open template at the ends, and a second forming tool for coupling an end region of the template adjacent to the open end thereof to form it, the first forming tool having a pin extending therefrom, the tools thus arranged so that when they are joined they form said end region in a desired manner that the pin defines said hole, wherein the pin has a length equal to the desired length of said hole and a distant surface, and said other tool has a plunger with a distal face which, prior to the formation, look at the distant end of the pin at a distance therefrom, the apparatus also comprising means for joining the distant face of the said face of the plunger in contact with each other during formation.