Process control method for a machine for manufacturing thermoplastic tubes

• US 6,165,395 A
• Filed: 11/25/1998
• Issued: 12/26/2000
• Est. Priority Date: 11/25/1998
• Status: Expired due to Term

• Current Assignee: Silgan Plastics Corp. (Silgan Holdings Incorporated)
• Original Assignee: Thatcher Tubes LLC (Silgan Holdings Incorporated)
• Inventors: Frazier, Thomas A., Kieras, Ronald E., Rhoades, John J.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Poe, Michael I.
• Application Number:
  US09/199,643
• Time in Patent Office: 762 Days
• Field of Search: 264/230, 264/296, 264/322, 264/327, 264/519, 264/40.1, 264/40.5, 264/40.6, 264/40.7, 425/392, 425/393, 425/403, 425/135, 425/140, 425/143, 425/139, 425/149, 425/150, 425/163, 156/64, 198/341.01, 198/341.03, 198/341.08
• US Class Current: 264/40.1
• CPC Class Codes: B29C 2049/7874 Preform or article shape, weight, defect or presence
• CPC Class Codes: B29C 2049/78805 Computer or PLC control
• CPC Class Codes: B29C 31/002 Handling tubes, e.g. transferring between shaping stations, loading on mandrels
• CPC Class Codes: B29C 49/78 Measuring, controlling or regulating
• CPC Class Codes: B29C 57/00 Shaping of tube ends, e.g. flanging, belling or closing; Apparatus therefor , e.g. collapsible mandrels
• CPC Class Codes: B29C 65/7882 said parts to be joined moving in a circular path
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/72341 for gases
• CPC Class Codes: B29C 66/9121 by measuring the temperature
• CPC Class Codes: B29C 66/91216 enabling contactless temperature measurements, e.g. using a pyrometer
• CPC Class Codes: B29C 66/91221 of the parts to be joined
• CPC Class Codes: B29C 66/91313 by measuring the voltage, i.e. the electric potential difference or electric tension
• CPC Class Codes: B29C 66/91315 by measuring the current intensity
• CPC Class Codes: B29C 66/9141 by controlling or regulating the temperature
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/91421 of the joining tools
• CPC Class Codes: B29C 66/91645 by steps
• CPC Class Codes: B29C 66/961 involving a feedback loop mechanism, e.g. comparison with a desired value
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0633 LDPE, i.e. low density polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2027/06 : PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2029/04 : PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/003 : PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material

Abstract

A machine for manufacturing thermoplastic tubes from hollow thermoplastic sleeves by a variety of different manufacturing processes. The machine is a single apparatus having an indexing table with a plurality of mandrels for holding hollow thermoplastic sleeves for the purpose of transporting the same around a closed manufacturing path. The manufacturing path of the machine is a series of stations which are mechanical devices for carrying out the manufacturing steps necessary to produce tubes from thermoplastic blank sleeves. The stations of the manufacturing path are modular so that they may be removed, added or rearranged; may be optionally connected to a process logic controller and may optionally have sensors for information feedback to the PLC device.

Claims

1. A feedback control method for controlling an apparatus for manufacturing finished thermoplastic tubes from thermoplastic sleeves, said apparatus having an indexing device rotatable about a fixed shaft, a means mounted on said indexing device for supporting sleeves for advancement along a closed path in response to rotation of said indexing device in a predetermined direction, a plurality of manufacturing stations for performing a plurality of different operations on said thermoplastic sleeves to form said finished thermoplastic tubes from said thermoplastic sleeves, and a PLC device, said method comprising:

sensing selected information about the quality of said thermoplastic sleeves and formed tubes at a plurality of locations around said closed path corresponding to said plurality of different operations of said plurality of manufacturing stations;

generating feedback control signals corresponding to said quality of said thermoplastic sleeves and formed tubes based on said sensed selected information;

inputting said feedback control signals to said PLC device; and

with use of said feedback control signals, controlling said plurality of different operations of said plurality of manufacturing stations with said PLC device to thereby control the quality of said finished thermoplastic tubes by identifying, monitoring and tracking defective formed tubes during said plurality of different operations of said plurality of manufacturing stations.

2. The method according to claim 1, which further comprises:

marking said formed tubes with individual indicia;

sensing selected information from said formed tubes marked with said individual indicia;

generating control signals corresponding to said formed tubes marked with said individual indicia based on said selected information;

inputting said control signals to said PLC device; and

with use of said control signals, identifying, monitoring and tracking defective formed tubes during said plurality of different operations of said plurality of manufacturing stations.

3. The method according to claim 1, wherein said generated signals from sensors are selected from the group consisting of mechanical, electronic, optical, pneumatic, hydraulic sensors and combinations thereof.

4. The method according to claim 1, which further comprises:

establishing setpoints for controlling said plurality of different operations of said plurality of manufacturing stations; and

with use of said feedback control signals based on said sensed selected information, controlling said plurality of different operations of said plurality of manufacturing stations within said setpoints.

5. The method according to claim 4, wherein said setpoints are predetermined and programmed into said PLC device.

6. A feedback control method for controlling an apparatus for manufacturing finished thermoplastic tubes from thermoplastic sleeves, said apparatus having an indexing device rotatable about a fixed shaft, a means mounted on said indexing device for supporting sleeves for advancement along a closed path in response to rotation of said indexing device in a predetermined direction, a plurality of manufacturing stations for performing a plurality of different operations on said thermoplastic sleeves to form said finished thermoplastic tubes from said thermoplastic sleeves, and a PLC device, said method comprising:

sensing selected information about said plurality of different operations of said plurality of manufacturing stations;

sensing selected information about the quality of said thermoplastic sleeves and formed tubes at a plurality of locations around said closed path corresponding to said plurality of different operations of said plurality of manufacturing stations;

generating feedback control signals corresponding to said plurality of different operations of said plurality of manufacturing stations based on said sensed selected information about said plurality of different operations of said plurality of manufacturing stations;

generating feedback control signals corresponding to said quality of said thermoplastic sleeves and formed tubes based on said sensed selected information about said quality of said thermoplastic sleeves and formed tubes;

inputting said feedback control signals to said PLC device; and

with use of said feedback control signals, controlling said plurality of different operations of said plurality of manufacturing stations with said PLC device to thereby control the quality of said finished thermoplastic tubes by identifying, monitoring and tracking defective formed tubes during said plurality of different operations of said plurality of manufacturing stations.

7. The method according to claim 6, which further comprises:

marking said formed tubes with individual indicia;

sensing selected information from said formed tubes marked with said individual indicia;

generating signals corresponding to said formed tubes marked with said individual indicia based on said selected information;

inputting said signals to said PLC device; and

with use of said signals, identifying, monitoring and tracking defective formed tubes during said plurality of different operations of said plurality of manufacturing stations.

8. The method according to claim 6, wherein said generated signals are from sensors selected from the group consisting of mechanical, electronic, optical, pneumatic, hydraulic sensors and combinations thereof.

9. The method according to claim 6, which further comprises:

establishing setpoints for controlling said plurality of different operations of said plurality of manufacturing stations; and

with use of said feedback control signals based on said sensed selected information, controlling said plurality of different operations of said plurality of manufacturing stations within said setpoints.

10. The method according to claim 9, wherein said setpoints are predetermined and programmed into said PLC device.