CA1225439A - Method and means for forming lines of weakness in closure caps and similar articles using a laser beam - Google Patents
Method and means for forming lines of weakness in closure caps and similar articles using a laser beamInfo
- Publication number
- CA1225439A CA1225439A CA000467606A CA467606A CA1225439A CA 1225439 A CA1225439 A CA 1225439A CA 000467606 A CA000467606 A CA 000467606A CA 467606 A CA467606 A CA 467606A CA 1225439 A CA1225439 A CA 1225439A
- Authority
- CA
- Canada
- Prior art keywords
- weakness
- closure
- line
- laser beam
- forming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/38—Removing material by boring or cutting
- B23K26/382—Removing material by boring or cutting by boring
- B23K26/384—Removing material by boring or cutting by boring of specially shaped holes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/362—Laser etching
- B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/40—Removing material taking account of the properties of the material involved
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/16—Composite materials, e.g. fibre reinforced
- B23K2103/166—Multilayered materials
- B23K2103/172—Multilayered materials wherein at least one of the layers is non-metallic
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Closures For Containers (AREA)
- Laser Beam Processing (AREA)
Abstract
METHOD AND MEANS FOR FORMING LINES OF
WEAKNESS IN CLOSURE CAPS AND SIMILAR
ARTICLES USING A LASER BEAM
ABSTRACT OF THE INVENTION
A method and means for forming a line of weakness in a molded plastic closure or the like using a laser beam for cutting or melting the plastic in an interrupted line of weakness or along a line extending partially through the article wall.
The method and means are used in the high speed manufacture of closure caps, for example, for defining tear strips or other portions of the closure caps which are torn loose for cap removal.
WEAKNESS IN CLOSURE CAPS AND SIMILAR
ARTICLES USING A LASER BEAM
ABSTRACT OF THE INVENTION
A method and means for forming a line of weakness in a molded plastic closure or the like using a laser beam for cutting or melting the plastic in an interrupted line of weakness or along a line extending partially through the article wall.
The method and means are used in the high speed manufacture of closure caps, for example, for defining tear strips or other portions of the closure caps which are torn loose for cap removal.
Description
5~39 TITLE: METHOD AND ME~NS FOR FOR~ING LINES OF
WEAK~ESS IN CLOSURE CAPS AND SI~ILAR
ARTICLES USING A LASER_B~AM
BACKGROUND OF THE INVENTION
The present invention relates to the use of a laser beam in the manufacture of closure caps and similar articles where a line of weakness~is incorporated in the article during manufacture. More particularly, the method and means covers the use of a laser beam for providing lines of weakness which define tear strips or other portions of closure caps which are removed by the user incident to opening the container and which are almost universally used in manufacturing tamper-evident molded plastic closure caps.
There are a large number of differing molded plastic closure caps which use one form or another of ~ line of weakness to provide tamper indicating properties. Presently these caps are formed in one or multi-stage molding processes where the lines of weakness are formed during the molding process itself. While this has resulted in satisfactory caps, such molds are relatively complicated since they require additional parts for forming the lines. These additional mold parts require means for moving them during the molding operation to permit the completed caps to be stripped from the molds without damage. These characteristics reduce manufacturing speed and occasionally produce unacceptable articles and also result in excPss mold wear since there often is a metal to metal contact resulting from the line forming action within the mold.
~Z5~39 In the method and means of ~he present invention, the caps are first molded in simplified molds which form the necessary caps without the formation of the lines of weakness.
Thereafter the caps are transferred to a laser station where the laser beam melts or cuts the necessary lines of weakness in closure caps to complete tlleir manufacture. The result is a simplified high speed cap manufacturing operation which requires only simple molds which operate indefinitely without excessive mold wear.
Examples of closure caps including lines of weakness are found in many prior caps including, for example, the caps described in issued United States patents No. 3,913,771, dated October 21, 1975 and No. 4,299,328, dated November 10, 1981.
Accordingly, an object of the present invention is to provide an improved method and means for manufacturing molded plastic closure caps and similar articles which incorporate lines of weakness or perforated lines.
Another object of the present invention is to provide a method and means of employing laser beams in forming lines of weakness in molded plastic articles such as closure caps and the like.
Another object of the pr~sent invention is to provide an improved laser method and means for use in closure cap manufacture.
Other and further objects of the present invention will become apparent upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:
FIG. l is a diagramatic illustration of the method and means of the present invention employing a laser beam in manufacturing closure caps and the like.
FIG. 2 is a horizontal sectional view taken along line
WEAK~ESS IN CLOSURE CAPS AND SI~ILAR
ARTICLES USING A LASER_B~AM
BACKGROUND OF THE INVENTION
The present invention relates to the use of a laser beam in the manufacture of closure caps and similar articles where a line of weakness~is incorporated in the article during manufacture. More particularly, the method and means covers the use of a laser beam for providing lines of weakness which define tear strips or other portions of closure caps which are removed by the user incident to opening the container and which are almost universally used in manufacturing tamper-evident molded plastic closure caps.
There are a large number of differing molded plastic closure caps which use one form or another of ~ line of weakness to provide tamper indicating properties. Presently these caps are formed in one or multi-stage molding processes where the lines of weakness are formed during the molding process itself. While this has resulted in satisfactory caps, such molds are relatively complicated since they require additional parts for forming the lines. These additional mold parts require means for moving them during the molding operation to permit the completed caps to be stripped from the molds without damage. These characteristics reduce manufacturing speed and occasionally produce unacceptable articles and also result in excPss mold wear since there often is a metal to metal contact resulting from the line forming action within the mold.
~Z5~39 In the method and means of ~he present invention, the caps are first molded in simplified molds which form the necessary caps without the formation of the lines of weakness.
Thereafter the caps are transferred to a laser station where the laser beam melts or cuts the necessary lines of weakness in closure caps to complete tlleir manufacture. The result is a simplified high speed cap manufacturing operation which requires only simple molds which operate indefinitely without excessive mold wear.
Examples of closure caps including lines of weakness are found in many prior caps including, for example, the caps described in issued United States patents No. 3,913,771, dated October 21, 1975 and No. 4,299,328, dated November 10, 1981.
Accordingly, an object of the present invention is to provide an improved method and means for manufacturing molded plastic closure caps and similar articles which incorporate lines of weakness or perforated lines.
Another object of the present invention is to provide a method and means of employing laser beams in forming lines of weakness in molded plastic articles such as closure caps and the like.
Another object of the pr~sent invention is to provide an improved laser method and means for use in closure cap manufacture.
Other and further objects of the present invention will become apparent upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:
FIG. l is a diagramatic illustration of the method and means of the present invention employing a laser beam in manufacturing closure caps and the like.
FIG. 2 is a horizontal sectional view taken along line
2-2 on FIG. 3.
FIG. 3 is a vertical sectional view of a molded plastic closure cap including a line of weakness formed using a laser beam in accordance with the method and means of the invention.
FIG. 4 is an enlarged fragmentary sectional view of a portion of a closure cap skirt having varying thickness for forming an interrupted line of weakness using a laser beam.
DESCRIPTION OF THE PR~FERRED EMBODIMENT
In this invention, laser beams are employed for the purpose of burning or melting plastic and thereby forming very thin cut lines or interrupted lines7 or in some cases grooves which extend only partially through the articles. In each case these laser beams are forming what are known as lines of weakness which facilitat-e a tearing-off or a rupturing of certain portions of closure caps and the like for tamper evident portions.
For example, in the drawing, a molded plastic closure cap l is illustrated havin~7 an upper sealing cap portion 2, 1~543~
with threads 3, for fastening it to a container mouth. A
tamper indicating ring 4 is provided which extends downwardly from the bottom of the cap skirt and which includes a bead 5 for locking engagement with a cooperating bead on the container.
A line of weakness 6 is provided between the cap portion 2 and the tamper indicating ring 4. The line 6 comprises a relatively thin slit interrupted by a number of connecting bridges 7 which hold the ring 4 in place. When the closure cap 1 is purposely removed or is removed by an unauthorized person, the ring 4 remains locked to the container so that it is torn free of the closure at the line 6 thereby indicating that the cap top portion 2 has been completely or partially removed.
Such lines of weakness are also employed on a number of closure caps which have a rip tab which is removed during the cap opening and where the line of weakness facilitates the removal of the tear strip by the package user. The laser method and means of the present invention is used to form such lines of weakness in a manner which will now be more fully described.
There are a number of laser devices which are commercially available and which generate laser beams which are beams of high intensity coherent light which is essentially monochromatic or having a single wave length. Thi.s characteristic permits the light energy of the laser beam to be focused at the surface of the closure caps into a very small contact area as small as a few thousandths of an inch or less. The lasers are available in a wide range of power or heat producing energy and may have an output power from a fraction of a watt to several hundred watts depending upon the particular application.
~ ~ ~ S ~3 Laser beams for forming lines of weakness in accordance with the present invention use a relatively sharp focus to concentrate the beam energy over the width required for the line of weakness.
Since plastic materials are poor ~hermal conductors or insulators, heating action at the surface of the plastic is localized and remains high for the area defining the width of the line of weakness. The temperature of the plastic in this localized area rises above the melting point providing the necessary cutting action. A satisfactory melting or cutting action is therefore obtained with the typical closure materials such as polyethylene, polystyrene or polypropylene or other moldable plastics having thermo-plastic charac~eristics.
FIG. 1 illustrates diagramatically a line forming appa~atus 8 such as might be used in accordance with the present invention for forming the line of weakness 6 in a closure cap l as illustrated in FIG. 3. The closure caps are mounted on a suitable spindle 9, probably in a multi-spindle machine and the caps are presented to the laser beam cutting station 10. At the station lO the cap l is rotated while being exposed to the laser beam ll generated by a laser, 12. The beam 11 is focused by a suitable focusing means, shown as a focusing lens 13 in FIG. 1, to strike the moving surface of the closure cap l at the desired position. In the formation of a line of weakness 6 of the type illustrated in FIG. 4, a single revolution at a relatively low speed may be employed with the beam 11 being turned on and off at pre-set intervals to form the necessary number of bridges which detachable connect the ring to the closure cap. The control of the beam may be by means of an Z543~
electro-mechanical or electronic s~itching device coordinated with the means 1~ for rotating the cap.
Alternatively, more than one turn of the cap may be used where a complete cut is done or where the line of weakness may extend only partially through the plastic cap material.
Other controls may be used in the form of sensing devices such as an electronic counter illustrated at 15 in FIG. 1.
Another means for forming an intermittent or interrupted line of weakness results from the shaping of the molded plastic article. In the case of a closure cap, for example as illustrated in ~IG. 4, the cap sidewall or skirt 16 is molded with portions of differing thickness 17 and 18. In this case the intensity of the laser beam 19 is adjusted for providing sufficient heating to melt or cut completely through the thinner portions 17 of the cap skirt 16 while cutting an equivalent distance into the thicker portions 18 therPby leaving plastic bridges 19 along the line of weakness 20.
It will be seen that an improved method and means has been described for the manufacture o~ closure caps and similar articles in which the previously difficult operation of forming lines of weakness in the molding process has been replaced by an efficient and simplified laser cutting process. The improved laser process insures a more accurate production of lines of weakness and also eliminates the need for complicated dies and the need for dies which include parts subject to significant wear.
As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invPntion and without sacrificing any of its advantages, it ;s to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.
FIG. 3 is a vertical sectional view of a molded plastic closure cap including a line of weakness formed using a laser beam in accordance with the method and means of the invention.
FIG. 4 is an enlarged fragmentary sectional view of a portion of a closure cap skirt having varying thickness for forming an interrupted line of weakness using a laser beam.
DESCRIPTION OF THE PR~FERRED EMBODIMENT
In this invention, laser beams are employed for the purpose of burning or melting plastic and thereby forming very thin cut lines or interrupted lines7 or in some cases grooves which extend only partially through the articles. In each case these laser beams are forming what are known as lines of weakness which facilitat-e a tearing-off or a rupturing of certain portions of closure caps and the like for tamper evident portions.
For example, in the drawing, a molded plastic closure cap l is illustrated havin~7 an upper sealing cap portion 2, 1~543~
with threads 3, for fastening it to a container mouth. A
tamper indicating ring 4 is provided which extends downwardly from the bottom of the cap skirt and which includes a bead 5 for locking engagement with a cooperating bead on the container.
A line of weakness 6 is provided between the cap portion 2 and the tamper indicating ring 4. The line 6 comprises a relatively thin slit interrupted by a number of connecting bridges 7 which hold the ring 4 in place. When the closure cap 1 is purposely removed or is removed by an unauthorized person, the ring 4 remains locked to the container so that it is torn free of the closure at the line 6 thereby indicating that the cap top portion 2 has been completely or partially removed.
Such lines of weakness are also employed on a number of closure caps which have a rip tab which is removed during the cap opening and where the line of weakness facilitates the removal of the tear strip by the package user. The laser method and means of the present invention is used to form such lines of weakness in a manner which will now be more fully described.
There are a number of laser devices which are commercially available and which generate laser beams which are beams of high intensity coherent light which is essentially monochromatic or having a single wave length. Thi.s characteristic permits the light energy of the laser beam to be focused at the surface of the closure caps into a very small contact area as small as a few thousandths of an inch or less. The lasers are available in a wide range of power or heat producing energy and may have an output power from a fraction of a watt to several hundred watts depending upon the particular application.
~ ~ ~ S ~3 Laser beams for forming lines of weakness in accordance with the present invention use a relatively sharp focus to concentrate the beam energy over the width required for the line of weakness.
Since plastic materials are poor ~hermal conductors or insulators, heating action at the surface of the plastic is localized and remains high for the area defining the width of the line of weakness. The temperature of the plastic in this localized area rises above the melting point providing the necessary cutting action. A satisfactory melting or cutting action is therefore obtained with the typical closure materials such as polyethylene, polystyrene or polypropylene or other moldable plastics having thermo-plastic charac~eristics.
FIG. 1 illustrates diagramatically a line forming appa~atus 8 such as might be used in accordance with the present invention for forming the line of weakness 6 in a closure cap l as illustrated in FIG. 3. The closure caps are mounted on a suitable spindle 9, probably in a multi-spindle machine and the caps are presented to the laser beam cutting station 10. At the station lO the cap l is rotated while being exposed to the laser beam ll generated by a laser, 12. The beam 11 is focused by a suitable focusing means, shown as a focusing lens 13 in FIG. 1, to strike the moving surface of the closure cap l at the desired position. In the formation of a line of weakness 6 of the type illustrated in FIG. 4, a single revolution at a relatively low speed may be employed with the beam 11 being turned on and off at pre-set intervals to form the necessary number of bridges which detachable connect the ring to the closure cap. The control of the beam may be by means of an Z543~
electro-mechanical or electronic s~itching device coordinated with the means 1~ for rotating the cap.
Alternatively, more than one turn of the cap may be used where a complete cut is done or where the line of weakness may extend only partially through the plastic cap material.
Other controls may be used in the form of sensing devices such as an electronic counter illustrated at 15 in FIG. 1.
Another means for forming an intermittent or interrupted line of weakness results from the shaping of the molded plastic article. In the case of a closure cap, for example as illustrated in ~IG. 4, the cap sidewall or skirt 16 is molded with portions of differing thickness 17 and 18. In this case the intensity of the laser beam 19 is adjusted for providing sufficient heating to melt or cut completely through the thinner portions 17 of the cap skirt 16 while cutting an equivalent distance into the thicker portions 18 therPby leaving plastic bridges 19 along the line of weakness 20.
It will be seen that an improved method and means has been described for the manufacture o~ closure caps and similar articles in which the previously difficult operation of forming lines of weakness in the molding process has been replaced by an efficient and simplified laser cutting process. The improved laser process insures a more accurate production of lines of weakness and also eliminates the need for complicated dies and the need for dies which include parts subject to significant wear.
As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invPntion and without sacrificing any of its advantages, it ;s to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.
Claims (3)
1. A method of forming a line of weakness in a generally cylindrical molded plastic closure having a generally cylindrical skirt comprising the steps of focusing a laser beam on the closure, providing relative motion between the beam and the closure, and adjusting beam intensity and rate of relative motion whereby the beam melts selected closure portions forming the line of weakness around said skirt.
2. The method as claimed in Claim 1 which includes the step of periodically interrupting the laser beam for forming spaced apertures to define the line of weakness in said closure skirt.
3. The method as claimed in Claim 1 wherein said plastic closure skirt has portions of differing thickness and which method includes the step of controlling the laser beam energy for melting completely through the thinner skirt portions and only partially through the thicker skirt portions in forming the line of weakness.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55104683A | 1983-11-14 | 1983-11-14 | |
| US551,046 | 1983-11-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1225439A true CA1225439A (en) | 1987-08-11 |
Family
ID=24199620
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467606A Expired CA1225439A (en) | 1983-11-14 | 1984-11-13 | Method and means for forming lines of weakness in closure caps and similar articles using a laser beam |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS60187491A (en) |
| CA (1) | CA1225439A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000044538A1 (en) * | 1999-01-28 | 2000-08-03 | Sacmi Cooperativa Meccanici Imola S.C.R.L. | Cutting machine for forming fracture lines allowing separation of tamper-evident rings from plastic caps |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62113008U (en) * | 1986-01-07 | 1987-07-18 | ||
| US4919821A (en) * | 1986-03-21 | 1990-04-24 | Nalco Chemical Company | Modified maleic anhydride polymers and the like for use as scale inhibitors |
| US4801388A (en) * | 1986-03-21 | 1989-01-31 | Nalco Chemical Company | Modified acrylamide polymers used as scale inhibitors |
| US4923634A (en) * | 1986-05-09 | 1990-05-08 | Nalco Chemical Company | Cooling water corrosion inhibition method |
| US4869828A (en) * | 1988-02-26 | 1989-09-26 | Nalco Chemical Company | Stabilization of iron in aqueous systems |
| US5035806A (en) * | 1989-05-15 | 1991-07-30 | Nalco Chemical Company | Scaling salt threshold inhibition and dispersion with hydrophilic/hydrophobic polymers |
| US5075390A (en) * | 1990-07-06 | 1991-12-24 | Nalco Chemical Company | Synthesis of hydrophobic/alkoxylated polymers |
| US5084520A (en) * | 1990-07-06 | 1992-01-28 | Nalco Chemical Company | Synthesis of hydrophobic/alkoxylated polymers |
| US5128419A (en) * | 1990-08-20 | 1992-07-07 | Nalco Chemical Company | Synthesis of tagged polymers by post-polymerization (trans) amidation reaction |
| JP6365342B2 (en) * | 2015-02-24 | 2018-08-01 | 京セラドキュメントソリューションズ株式会社 | Method for producing lid by laser light irradiation, and method for producing container provided with the lid |
-
1984
- 1984-11-13 CA CA000467606A patent/CA1225439A/en not_active Expired
- 1984-11-14 JP JP59238728A patent/JPS60187491A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000044538A1 (en) * | 1999-01-28 | 2000-08-03 | Sacmi Cooperativa Meccanici Imola S.C.R.L. | Cutting machine for forming fracture lines allowing separation of tamper-evident rings from plastic caps |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60187491A (en) | 1985-09-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |