CA1114116A - Plastic drum - Google Patents
Plastic drumInfo
- Publication number
- CA1114116A CA1114116A CA297,588A CA297588A CA1114116A CA 1114116 A CA1114116 A CA 1114116A CA 297588 A CA297588 A CA 297588A CA 1114116 A CA1114116 A CA 1114116A
- Authority
- CA
- Canada
- Prior art keywords
- mould
- drum
- chimes
- sections
- frusto
- 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
- 239000004033 plastic Substances 0.000 title description 5
- 229920003023 plastic Polymers 0.000 title description 5
- 239000000463 material Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 7
- 229920001169 thermoplastic Polymers 0.000 claims abstract description 4
- 239000004416 thermosoftening plastic Substances 0.000 claims abstract description 4
- 238000007664 blowing Methods 0.000 claims description 4
- 238000000071 blow moulding Methods 0.000 abstract description 5
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000012815 thermoplastic material Substances 0.000 description 1
Landscapes
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Toys (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a method of forming a blow-moulded drum of thermo-plastics material provided with projecting hoops, comprising, blow-moulding a drum in a mould, the mould being formed of laterally displaceable mould sections which, in a closed position, define a mould cavity having side walls, the mould sections being further divided into separate parts in planes in which drum chimes are to be formed, the separate parts of the mould sections defining between them in an extended position of the mould parts, gaps in the side walls of the mould cavity whereby, during the blow-moulding step, material is blown into the gaps to form annular rings around the drum, and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes. The drum has frusto-conical end portions disposed outwardly of the chimes.
The invention provides a method of forming a blow-moulded drum of thermo-plastics material provided with projecting hoops, comprising, blow-moulding a drum in a mould, the mould being formed of laterally displaceable mould sections which, in a closed position, define a mould cavity having side walls, the mould sections being further divided into separate parts in planes in which drum chimes are to be formed, the separate parts of the mould sections defining between them in an extended position of the mould parts, gaps in the side walls of the mould cavity whereby, during the blow-moulding step, material is blown into the gaps to form annular rings around the drum, and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes. The drum has frusto-conical end portions disposed outwardly of the chimes.
Description
The invention relates to a method of forming a blow-moulded drum of thermoplastic's material provided with~ ~4 which encircle the drum shell and/or are arranyed at the top and bottor,l portions thereof.
cl ~ e s It is known to insert prefabricated ~6~g into a blow-mould when forming such drums and, on inflating the extruded c))ir~etube, the he~p is welded to the tube, which has been inflated to a drum shape. This causes problems insofar as a mold part encompassing the hollow article tends to be welded thereto. For this purpose, the blow-moulds must be provided with complex devices, which receive the mould parts as an intermediate mould with separate locking members. When telescoping the principal mould the intermediate mould is received as an insert and in the closed state it forms a unit along with the principal mould.
For example, in the production of wide-necked drums it is known to clamp prefabricated top rings of thermoplastic material for reinforcing the drum opening (with the principal mould open) into an intermediate mould, arranged centrally below the die relief of the blow machine so that the tube which is being lowered passes through the centre of the top ring. On closing the two mould halves the intermediate mould slides into ` -corresponding recesses so that the principal mould and the intermediate mould form a unit.
Moreover, in wide-necked drums having no top rings it is known to connect a prefa~ricated bottom ring with the drum being formed during the blow-moulding operation in that the ring is placed on a separate lower one-part mould section in the lowered state, whereupon it is centered. Ilowever, this makes it necessary to seal the lowering tube with a special tool and, to remove as waste the residual tube formed behind the point of sealing. The technique of sealing the tube and removing the waste is complicated and time-consuming. On completing the .~ - 1 -:
: ` ';' -.!:.
interrnedlate operation the main mould halves are telescoped and the lower mould section is raised along with the bottom ring so -that the entire mould is closed.
It is technically expensive to manufacture a hollow article, for example, a drum having separately prefabricated top and bottom rings, by blGw-moulding. However, top and bottom rings are desirable in drums because they can be more readily handled, rolled and picked up by cranes. This applies particularly to plastic drums. secause a filled plastic drum changes its shape it is difficult to put it on the ground and roll it. Rolling the drum over the ground edge with the drum raised in an inclined position is very difficult to carry out because of the surface deformation of the shell-ground transition. Moreover, a suitable means of application at the shell-top transition in order to put the drum into rolling motion over the ground edge or to insert crane nooks for the ; purpose of loading is lacking.
Therefore, top and bottom rings of metal have also been subsequently mounted on blow-moulded hollow articles. For this reason costly mounting operations and subsequent permanent deformations of the metal rings must be accepted. Moreover, owing to the difference in expansion, coefficients of plastics and metals at high temperatures, which may be in the ratio of seven to one, the rings which are mechancially held on the plastics tend to separate.
It is the aim of the invention to design a chimed drum without having to place separately prefabricated chimes lnto the blow-mould or without having to mount them on the drum - subsequently.
According to a first aspect of the invention there is provided a method of forming a blow-moulded drum of thermo-plastics material provided with projecting chimes, comprising providing a '
cl ~ e s It is known to insert prefabricated ~6~g into a blow-mould when forming such drums and, on inflating the extruded c))ir~etube, the he~p is welded to the tube, which has been inflated to a drum shape. This causes problems insofar as a mold part encompassing the hollow article tends to be welded thereto. For this purpose, the blow-moulds must be provided with complex devices, which receive the mould parts as an intermediate mould with separate locking members. When telescoping the principal mould the intermediate mould is received as an insert and in the closed state it forms a unit along with the principal mould.
For example, in the production of wide-necked drums it is known to clamp prefabricated top rings of thermoplastic material for reinforcing the drum opening (with the principal mould open) into an intermediate mould, arranged centrally below the die relief of the blow machine so that the tube which is being lowered passes through the centre of the top ring. On closing the two mould halves the intermediate mould slides into ` -corresponding recesses so that the principal mould and the intermediate mould form a unit.
Moreover, in wide-necked drums having no top rings it is known to connect a prefa~ricated bottom ring with the drum being formed during the blow-moulding operation in that the ring is placed on a separate lower one-part mould section in the lowered state, whereupon it is centered. Ilowever, this makes it necessary to seal the lowering tube with a special tool and, to remove as waste the residual tube formed behind the point of sealing. The technique of sealing the tube and removing the waste is complicated and time-consuming. On completing the .~ - 1 -:
: ` ';' -.!:.
interrnedlate operation the main mould halves are telescoped and the lower mould section is raised along with the bottom ring so -that the entire mould is closed.
It is technically expensive to manufacture a hollow article, for example, a drum having separately prefabricated top and bottom rings, by blGw-moulding. However, top and bottom rings are desirable in drums because they can be more readily handled, rolled and picked up by cranes. This applies particularly to plastic drums. secause a filled plastic drum changes its shape it is difficult to put it on the ground and roll it. Rolling the drum over the ground edge with the drum raised in an inclined position is very difficult to carry out because of the surface deformation of the shell-ground transition. Moreover, a suitable means of application at the shell-top transition in order to put the drum into rolling motion over the ground edge or to insert crane nooks for the ; purpose of loading is lacking.
Therefore, top and bottom rings of metal have also been subsequently mounted on blow-moulded hollow articles. For this reason costly mounting operations and subsequent permanent deformations of the metal rings must be accepted. Moreover, owing to the difference in expansion, coefficients of plastics and metals at high temperatures, which may be in the ratio of seven to one, the rings which are mechancially held on the plastics tend to separate.
It is the aim of the invention to design a chimed drum without having to place separately prefabricated chimes lnto the blow-mould or without having to mount them on the drum - subsequently.
According to a first aspect of the invention there is provided a method of forming a blow-moulded drum of thermo-plastics material provided with projecting chimes, comprising providing a '
-2-.
; mould having laterally dlsplaceable mould sections which in a closed position, define a mould cavity having side walls : extending inwardly at the ends of the mould to form frusto-conical sections, the mould sections being further divided into separate parts in upper and lower planes spaced respectively from the top and bottom of the mould cavity in which upper and lower drum chimes are to be formed, said planes being located inwardly of sai.d frusto-conical sections, the separate parts ;. of the mould sections defining between them, in an extended position of the mould parts, gaps in the side walls of the mould cavity, and a projection being formed on one of the mould parts adjacent each said dividing plane, said projection forming a recess between the side wall of the mould and said projection .~ : :
directed towards the adjacent end of the mould cavity; inserting ::
a parison in said mould cavity; blowing said parison -to form the drum while allowing the material to enter said gaps and form annular rings around the drum; and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes, each chime being L-shaped and having a lip ~0 extending axially towards the adjacent end of the drum.formed by said projection and recess, and said chimes being dispos2d - inwardly of frusto-conical end portions of the drum formed by said frusto-conical sections of the mould.
~ According to a second aspect of the invention there ; is provided a.blow-moulded drum having frusto-conical end ~ sections.and upper and lower L-shaped chimes formed integrally - with the walls of the drum and spaced respectively from the top and bottom of the drum, having a lip extending axially towards the respective adjacent end of the drum; said upper and lower ~ 30 chimes being located inwardly of said frusto-conical sections.
The invention will now be described in more detail, ;;.
by way of example only, with reference to the accompanying ., '~ .
SL$~
drawings, in which~
Figure 1 is a sectional view of a blown drum in a mould, illustrating two steps of the blow-moulding process in accordance with the invention;
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Figure 2 is a detailed view in section, of a part of the drum and mould in Figure 1 prior to contracting the mould and Figure 3 shows the part of the drum and mould shown in Figure 2, but after contracting the mould to form the finished chimes.
In Figure 1, the mould is formed of two mould halves 7 and 8 which are laterally displaceable from an open position (not shown) to a closed position shown in Figure 1. In the closed position, the two mould halves 7,8 meet along a central dividing plane 9. The upper and lower ends of the mould are closed by mould end sections 10, 11 and 12, 13 respectively.
The mould end sections 10, 11, 12, 13 are independently movable in the vertical direction ~rom an extended position, shown in the left half of Figure 3~ to a contracted position shown in the right half of Figure 3. The lower end of the mould is provided with nozzles 14, 15 for blowing air into the mould to inflate a tube placed therein to the shape of the mould.
The upper and lower ends of the two halves 7, 8 of the mould forming the side walls of the drum are stepped to ?
provide end portions 16, 17 of enlarged diameter relative to the interior of the mould. The end sectons 10, 11, 12, 13 are -provided on their inner surfaces, with projecting mould closure parts 18, 19, 20, 21 which extend into the enlarged end portions 16, 17 of the mould when the two halves 7, 8 of the mould are in the closed position as shown in Figure 1.
Lips 22, 23, 24, 25 project inwardly from the inner surfaces of the respective closure portions 18, 19, 20, 21 and ~-are spaced a small distance from the walls of the enlarged portions 16, 17 of the mould to define recesses 26, 27 (see left side of Figure 1~. As shown more clearly in Figures 2 and 3 the inner side walls 30 of the mould abo~e the lips 22, 23 -4~
.
, ~
extends inwardly such that the upper section of the mould has a frusto-conical shape. This forms a frusto-conical section on the finished drum above the upper chime 2. A similar arrange-ment is provided at the bottom of the drum.
In use, the mould halves 7, 8 are first moved to the open position, and the mould sections 10, 11, 12, 13 are fully extended outwardly. A mould blank in the form of a tube is placed in the mould and the mould halves 7, 8 are brought toge-ther into the closed position shown in Figure 1. Air is then injected into the mould and the blank is blown outwardly to take the shape of the mould. Annular rings 28, 29 are formed in the gap between the lips 22, 23, 24, 25 and the corresponding shoulders formed by the stepped portions of the mould. Part of the ring 28 is shown in more detail in Figure 2. When the blowing operation has been completed, the end sections of the mould are drawn together to the contracted position shown in ~ ;
Figure ~; and the right half of Figure 1. This causes the materia~ forminct the rings 28, 29 to be s~ueezed into the recesses 26, 27 and thereby form the lips 6 (Figure 3) of the O chimes 2. ~igure 3 shows the material forming the rin~ 28 in Figure 2 fully within the recess 26 which forms a secondary mould for the lips 6 of the chimes.
Figure 1 shows a mould for forming the ~ and lower chimes ~, but clearly, intermediate chimes 2 can be formed in -~
a similar manner. In this case, the mould halves 7l 8 are also divided in the planes where it is desired to form the intermediate chimes. A lip is formed on the part of the mould half above the division, and a co-operating stepped shoulder is formed in the part of the mould half below the division to define a gap in which an annular ring is formed in the blow-moulding operation. When the mould is contracted lcngitudinally, all the chimes 2, ~ are stamped ou~ in a similar way.
~5~
Thus, it will be seen that, in the described process, ~ :
the chimes 2, ~ are actually formed out of the material forming ~-~
the drum and are integral therewith.
The tube or blank inserted in the mould may also be referred to as a parison.
' ` ~' 0 ,~
~ -';
-6- ~
- - , ;, , . , . .. ~
; mould having laterally dlsplaceable mould sections which in a closed position, define a mould cavity having side walls : extending inwardly at the ends of the mould to form frusto-conical sections, the mould sections being further divided into separate parts in upper and lower planes spaced respectively from the top and bottom of the mould cavity in which upper and lower drum chimes are to be formed, said planes being located inwardly of sai.d frusto-conical sections, the separate parts ;. of the mould sections defining between them, in an extended position of the mould parts, gaps in the side walls of the mould cavity, and a projection being formed on one of the mould parts adjacent each said dividing plane, said projection forming a recess between the side wall of the mould and said projection .~ : :
directed towards the adjacent end of the mould cavity; inserting ::
a parison in said mould cavity; blowing said parison -to form the drum while allowing the material to enter said gaps and form annular rings around the drum; and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes, each chime being L-shaped and having a lip ~0 extending axially towards the adjacent end of the drum.formed by said projection and recess, and said chimes being dispos2d - inwardly of frusto-conical end portions of the drum formed by said frusto-conical sections of the mould.
~ According to a second aspect of the invention there ; is provided a.blow-moulded drum having frusto-conical end ~ sections.and upper and lower L-shaped chimes formed integrally - with the walls of the drum and spaced respectively from the top and bottom of the drum, having a lip extending axially towards the respective adjacent end of the drum; said upper and lower ~ 30 chimes being located inwardly of said frusto-conical sections.
The invention will now be described in more detail, ;;.
by way of example only, with reference to the accompanying ., '~ .
SL$~
drawings, in which~
Figure 1 is a sectional view of a blown drum in a mould, illustrating two steps of the blow-moulding process in accordance with the invention;
:, .~ ~
, . .
.,: ..
: -i ,, ,; :
.
:i 20 ~ .
~, . , - .
. '~ .
~" :
.; ' ' . . .
.;.
. .
, ~ .
~'~ 3Q ~
.: :
:.
', ,~b, -3a-. - - . , ~ . ~
Figure 2 is a detailed view in section, of a part of the drum and mould in Figure 1 prior to contracting the mould and Figure 3 shows the part of the drum and mould shown in Figure 2, but after contracting the mould to form the finished chimes.
In Figure 1, the mould is formed of two mould halves 7 and 8 which are laterally displaceable from an open position (not shown) to a closed position shown in Figure 1. In the closed position, the two mould halves 7,8 meet along a central dividing plane 9. The upper and lower ends of the mould are closed by mould end sections 10, 11 and 12, 13 respectively.
The mould end sections 10, 11, 12, 13 are independently movable in the vertical direction ~rom an extended position, shown in the left half of Figure 3~ to a contracted position shown in the right half of Figure 3. The lower end of the mould is provided with nozzles 14, 15 for blowing air into the mould to inflate a tube placed therein to the shape of the mould.
The upper and lower ends of the two halves 7, 8 of the mould forming the side walls of the drum are stepped to ?
provide end portions 16, 17 of enlarged diameter relative to the interior of the mould. The end sectons 10, 11, 12, 13 are -provided on their inner surfaces, with projecting mould closure parts 18, 19, 20, 21 which extend into the enlarged end portions 16, 17 of the mould when the two halves 7, 8 of the mould are in the closed position as shown in Figure 1.
Lips 22, 23, 24, 25 project inwardly from the inner surfaces of the respective closure portions 18, 19, 20, 21 and ~-are spaced a small distance from the walls of the enlarged portions 16, 17 of the mould to define recesses 26, 27 (see left side of Figure 1~. As shown more clearly in Figures 2 and 3 the inner side walls 30 of the mould abo~e the lips 22, 23 -4~
.
, ~
extends inwardly such that the upper section of the mould has a frusto-conical shape. This forms a frusto-conical section on the finished drum above the upper chime 2. A similar arrange-ment is provided at the bottom of the drum.
In use, the mould halves 7, 8 are first moved to the open position, and the mould sections 10, 11, 12, 13 are fully extended outwardly. A mould blank in the form of a tube is placed in the mould and the mould halves 7, 8 are brought toge-ther into the closed position shown in Figure 1. Air is then injected into the mould and the blank is blown outwardly to take the shape of the mould. Annular rings 28, 29 are formed in the gap between the lips 22, 23, 24, 25 and the corresponding shoulders formed by the stepped portions of the mould. Part of the ring 28 is shown in more detail in Figure 2. When the blowing operation has been completed, the end sections of the mould are drawn together to the contracted position shown in ~ ;
Figure ~; and the right half of Figure 1. This causes the materia~ forminct the rings 28, 29 to be s~ueezed into the recesses 26, 27 and thereby form the lips 6 (Figure 3) of the O chimes 2. ~igure 3 shows the material forming the rin~ 28 in Figure 2 fully within the recess 26 which forms a secondary mould for the lips 6 of the chimes.
Figure 1 shows a mould for forming the ~ and lower chimes ~, but clearly, intermediate chimes 2 can be formed in -~
a similar manner. In this case, the mould halves 7l 8 are also divided in the planes where it is desired to form the intermediate chimes. A lip is formed on the part of the mould half above the division, and a co-operating stepped shoulder is formed in the part of the mould half below the division to define a gap in which an annular ring is formed in the blow-moulding operation. When the mould is contracted lcngitudinally, all the chimes 2, ~ are stamped ou~ in a similar way.
~5~
Thus, it will be seen that, in the described process, ~ :
the chimes 2, ~ are actually formed out of the material forming ~-~
the drum and are integral therewith.
The tube or blank inserted in the mould may also be referred to as a parison.
' ` ~' 0 ,~
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- - , ;, , . , . .. ~
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of forming a blow-moulded drum of thermoplastics material provided with projecting chimes, comprising providing a mould having laterally displaceable mould sections which in a closed position, define a mould cavity having side walls extending inwardly at the ends of the mould to form frusto-conical sections, the mould sections being further divided into separate parts in upper and lower planes spaced respectively from the top and bottom of the mould cavity in which upper and lower drum chimes are to be formed, said planes being located inwardly of said frusto-conical sections, the separate parts of the mould sections defining between them, in an extended position of the mould parts, gaps in the side walls of the mould cavity, and a projection being formed on one of the mould parts adjacent each said dividing plane, said projection forming a recess between the side wall of the mould and said projection directed towards the adjacent end of the mould cavity; inserting a parison in said mould cavity; blowing said parison to form the drum while allowing the material to enter said gaps and form annular rings around the drum;
and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes, each chime being L-shaped and having a lip extending axially towards the adjacent end of the drum formed by said projection and recess, and said chimes being disposed inwardly of frusto-conical end portions of the drum formed by said frusto-conical sections of the mould.
and contracting the mould parts along the drum axis to stamp the annular rings into the projecting chimes, each chime being L-shaped and having a lip extending axially towards the adjacent end of the drum formed by said projection and recess, and said chimes being disposed inwardly of frusto-conical end portions of the drum formed by said frusto-conical sections of the mould.
2. A method as claimed in claim 1, wherein a chime is also formed in the middle region of the drum.
3. A blow-moulded drum having frusto-conical end sections and upper and lower L-shaped chimes formed integrally with the walls of the drum and spaced respectively from the top and bottom of the drum, having a lip extending axially towards the respective adjacent end of the drum, said upper and lower chimes being located inwardly of said frusto-conical sections.
4. A blow-moulded drum as claimed in claim 3, further having an intermediate chime between said upper and, lower chimes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,588A CA1114116A (en) | 1978-02-23 | 1978-02-23 | Plastic drum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,588A CA1114116A (en) | 1978-02-23 | 1978-02-23 | Plastic drum |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1114116A true CA1114116A (en) | 1981-12-15 |
Family
ID=4110850
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,588A Expired CA1114116A (en) | 1978-02-23 | 1978-02-23 | Plastic drum |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1114116A (en) |
-
1978
- 1978-02-23 CA CA297,588A patent/CA1114116A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |