Process for manufacturing an injection device of the pre-filled type containing a dose of liquid for injection and injection device produced

A process for manufacturing and assembling a pre-filled injection device including an injection needle (116, 15, 23, 47), said process comprising the steps of:

• producing a tubular syringe body (101, 121, 1, 20, 42) of a deformable plastic material having a distal end and a proximal end, equipping said proximal end with finger-hold elements (105, 5, 26, 53) and equipping said distal end with an external locking element (104, 123, 7-9, 27-29, 54-56) suitable for deforming radially between a retracted position and a dilated position,
• producing a tubular sheath (109, 10, 31, 58) of a shape suitable for sliding along said syringe body, providing said tubular sheath with an internal locking element (110, 111, 11, 32, 59) located at a proximal end of said tubular sheath;
• locating said proximal end of said sheath adjacent the distal end of said syringe body and slidably inserting said sheath into said syringe body, said sliding being accommodated by radial retraction of said locking element and bringing the said proximal end of said sheath to a position adjacent to said finger-hold elements of said syringe body;
• introducing into said syringe body a rigid pre-filled container (114, 13, 34, 61) having an external cross-section which cooperates with the internal cross-section of said syringe body and suitable for bringing said external locking element of said syringe body into a dilated position thereby preventing further radial deformation of said locking element, and equipping said rigid container with means (119, 120;
• 18, 19;
• 37, 38;
• 62) for injecting liquid from said pre-filled container and locking said syringe body and said rigid container against further longitudinal movement with respect to each other.