Method for stretch-blow moulding a container, including measuring the movement of the stretch rod during a boxing operation

• US 9,744,712 B2
• Filed: 11/14/2013
• Issued: 08/29/2017
• Est. Priority Date: 11/20/2012
• Status: Active Grant

• Current Assignee: Sidel Participations (Tetra Laval Holdings BV)
• Original Assignee: Sidel Participations (Tetra Laval Holdings BV)
• Inventors: Letestu, Mickael, Protais, Pierrick
• Primary Examiner(s): Davis, Robert B
• Application Number:
  US14/646,148
• Publication Number:
  US 20150298386A1
• Time in Patent Office: 1,384 Days
• CPC Class Codes: B29C 2049/023 using inherent heat of the preform, i.e. 1 step blow moulding
• CPC Class Codes: B29C 2049/4892 Mould halves consisting of an independent main and bottom part
• CPC Class Codes: B29C 2049/7831 characterised by pressure values or ranges
• CPC Class Codes: B29C 2049/7832 Blowing with two or more pressure levels
• CPC Class Codes: B29C 2049/7879 Stretching, e.g. stretch rod
• CPC Class Codes: B29C 49/06 Injection blow-moulding
• CPC Class Codes: B29C 49/12 Stretching rods
• CPC Class Codes: B29C 49/1232 Magnetic
• CPC Class Codes: B29C 49/30 having movable moulds or mould parts
• CPC Class Codes: B29C 49/36 rotatable about one axis
• CPC Class Codes: B29C 49/541 having a recessed undersurface
• CPC Class Codes: B29C 49/5612 characterised by bottom part movement
• CPC Class Codes: B29C 49/78 Measuring, controlling or regulating
• CPC Class Codes: B29C 49/783 blowing pressure
• CPC Class Codes: B29K 2067/003 PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29L 2031/712 Containers; Packaging elements or accessories, Packages closures therefor B29L2031/56; ink or toner cartridges B29L2031/7678; squeeze tubes B29L2023/20; suitcases B29L2031/7418

Abstract

Disclosed is a method for manufacturing a container (2) from a blank (3) made of plastic material, in a stretch-blow molding unit (7) including: a mold (11) provided with a wall (13) and a mold base (14) which is axially movable relative to the wall (13) between a low position and a raised position; a stretch rod (22) which is axially movable relative to the mold (11) between a high position and a low position; the method including: a phase of inserting the blank (3) in the mold (11); a phase of stretch-blow molding; a phase of boxing; a phase of determining the start and end of the boxing phase, respectively, by detecting the movement of the rod (22) from the low position thereof and the stopping of the rod (22) at the raised position thereof.

Claims

1. Method for producing, from a blank (3) of plastic material, a container (2) having a body (4) and a base (6), in a stretch-blow-molding unit (7) comprising:

a mold (11) provided with a wall (13) having the shape of the body (4) of the container (2), and with a mold base (14) having the shape of the base (6) of the container (2), the mold base (14) being movable axially relative to the wall (13) between a low position and a raised position;

a stretch rod (22) that is movable axially relative to the mold (11) between a high position in which the rod (22) is outside of the mold, and a low position in which the rod (22) locally presses the blank (3) against the mold base (14) in the low position;

this method comprising;

a phase for introduction of the blank (3) into the mold (11);

a stretch-blow-molding phase, during which a fluid under pressure is injected into the blank (3) and the stretch rod (22) is moved from the high position to the low position;

a boxing phase, during which the mold base (14), initially in low position, is moved to the raised position, and during which the stretch rod (22), accompanying the mold base (14), is moved from the low position to a raised position corresponding to the raised position of the mold base (14);

wherein the method comprises the determination of the start of the mold base (14) from the low position by detection of the movement of the rod (22) from the low position, and the determination of the arrival of the mold base (14) at the raised position by detection of the stopping of the rod (22) at the raised position.

2. Method according to claim 1, further comprising determining the instantaneous position of the mold base (14) between the low position and the raised position by detecting the instantaneous position of the rod (22) between the low position and the raised position.

3. Method according to claim 1, further comprising an operation for adjustment of a movement order for the mold base (14), when the start of the mold base (14) does not correspond to a predetermined theoretical start.

4. Method according to claim 1, further comprising an operation for adjustment of the flow rate of a solenoid valve (19) connecting an actuator (17) carrying the mold base (14) to a source (18) of fluid under pressure, when the actual arrival of the mold base (14) does not correspond to a predetermined theoretical arrival.

9. Method according to claim 2, further comprising an operation for adjustment of a movement order for the mold base (14), when the start of the mold base (14) does not correspond to a predetermined theoretical start.

10. Method according to claim 2, further comprising an operation for adjustment of the flow rate of a solenoid valve (19) connecting an actuator (17) carrying the mold base (14) to a source (18) of fluid under pressure, when the actual arrival of the mold base (14) does not correspond to a predetermined theoretical arrival.

11. Method according to claim 3, further comprising an operation for adjustment of the flow rate of a solenoid valve (19) connecting an actuator (17) carrying the mold base (14) to a source (18) of fluid under pressure, when the actual arrival of the mold base (14) does not correspond to a predetermined theoretical arrival.

12. Method according to claim 4, further comprising an operation for adjustment of the flow rate of a solenoid valve (19) connecting an actuator (17) carrying the mold base (14) to a source (18) of fluid under pressure, when the actual arrival of the mold base (14) does not correspond to a predetermined theoretical arrival.

5. Stretch-blow-molding unit (7) for producing, from a blank (3) of plastic material, a container (2) having a body (4) and a base (6), this stretch-blow-molding unit (7) comprising:

a mold (11) provided with a wall (13) having the shape of the body (4) of the container (2) and with a mold base (14) having the shape of the base (6) of the container (2), the mold base (14) being movable axially relative to the wall (13) between a low position and a raised position;

a stretch rod (22) that is movable axially relative to the mold (11) between a high position in which the rod (22) is outside of the mold, and a low position in which the rod (22) locally presses the blank (3) against the mold base (14) in the low position;

the stretch-blow-molding unit (7) further comprising means (23) for detecting at least movement of the rod (22) from the low position, and stopping of the rod (22) at a raised position corresponding to the raised position of the mold base (14), and a central processing unit (10) designed to deduce the start of the mold base (14) from the low position, and the arrival of the mold base (14) at the raised position.

6. Stretch-blow-molding unit (7) according to claim 5, wherein the detecting means appear in the form of an optical sensor (23).

7. Stretch-blow-molding unit (7) according to claim 6, wherein the optical sensor (23) is a laser sensor.

8. Stretch-blow-molding unit (7) according to claim 6, further comprising a frame (20), wherein the stretch rod (22) is mounted on a carriage (21) that is mobile relative to the frame (20), and wherein the sensor (23) is attached to the frame (20) and points toward the carriage (21).

13. Stretch-blow-molding unit (7) according to claim 7, further comprising a frame (20), wherein the stretch rod (22) is mounted on a carriage (21) that is mobile relative to the frame (20), and wherein the sensor (23) is attached to the frame (20) and points toward the carriage (21).