CA1096788A

CA1096788A - Drum

Info

Publication number: CA1096788A
Application number: CA319,769A
Authority: CA
Inventors: Theo Hammes
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-04-08
Filing date: 1979-01-17
Publication date: 1981-03-03
Also published as: NO781990L; DE2815326A1; IL54703A; BR7803954A; IT7824233A0; NO147549B; SU1053739A3; SE437967B; NO147549C; NL7806062A; FR2421805A1; DE2815326C2; FR2421805B1; IL54703A0; JPS575730B2; BE867560A; ES236757U; AU520740B2; DK222578A; AU3760578A

Abstract

ABSTRACT OF THE DISCLOSURE
An L-shaped roller chime is provided adjacent each end of a closed head drum. The drum is formed of a thermoplastic material and is blown into shape in an openable mold so that the drum has axially extending dividing seams. Each L-shaped chime has a first leg extending outwardly from the drum and a second leg extending generally perpendicularly to the first leg and in the axial direction of the drum. The depth of the groove formed by the first and second legs and the outer drum surface is uni-form, however, the thickness of the first leg varies from a maxi-mum at the dividing seams to a minimum intermediate the seams.

Description

~0~6788 Tlle present invellt;on is I;rectcd to a c]o;ed head drum rnade of tlle~ op1astic material alld blown into shape w;thin an openable mold. The drum has roller chimes of L--shaped cross section which extend around the ouler surface of the drum body adjacent the head elld and the bot-~om end. The ro]ler ch;mes are formed integrally in the drum body. The roller chimes in corn-bina-tion with the outer surface of the drum body forrn a recess or groove with the opening of the groove directed toward the adjacent end of the drum. 'rhe (~rooves provide engagement sur-faces for a gripping and transporting tool.
As compared to drums in which prefabricated ro]lerhoops are inserted into the blowing mold so that the hoops are welded to the drum when the extruded parison is inflated, drums incorporating roller chimes as described above have the advan-tage that production is much simpler. Since the roller chimes formed integrally with the drum body are component parts of the drum, they cannot be displaced during rough handling.
The blowing mold used for producing such closed head drums consists of two mold halves which are separable along a vertical plane, that is, the plane extending in the axial direc-tion of the drum. The upper and lower region of each mold half is horizontally divided to provide mold parts which slide one into the other. Such a mold is disclosed in our co-pending Canadian application no. 297,588 filed on Feb. 23, 1978.
When the parison is lowered out of the extrusion head of the blowing machine, the mold halves are in the separated position so that the parison can enter into the opened blowing mold. At this time, the mold parts in each mold half which slide relative to one another are opened. After the parison is lowered in the axial direction of the drum into the mold, the two mold halves are closed and the blowing process commences.

Air flowing in through a mandrel expands the parison so that it 1~6788 is pressed outwardly against the inner wall of t-he closed mold and, as a result, assumes the predetermined shape of the drum.
With the upper and lower mold parts of each mold half disposed in an open position, the material of -the parison enters into the recesses formed by the open mold parts. With such a mold construction, flanged rings are formed open -toward the inside.
When the mold halves have been closed, but before the inflation step has taken place, -the parison is held in the mold by being clamped, at its upper and lower ends, between the mold halves. This causes these ends to take on generally the shape of a flattened tube.Clearly, as the parison is inflated, the control regions of the flattened tube will have further to expand outwardly than the edge regions before they strike the mold walls. This leads to an uneven thickness of the walls of the drum around its periphery adjacent its ends. The parts of the drum walls in the region of the dividing seams of the mold, that in the regions of the edges of the flattened parison have a greater thickness than those parts which are angularly dis-placed by 90 from the dividing seams, that is those parts which formed the control region of the parison prior to the inflation step.
Subsequently, the mold parts are moved relative to one another into a closed position. The mold parts which can be moved relative to one another are shaped to provide the roller chime configuration and the material pressed into the opening provided by the mold parts forms the roller chimes when the mold parts are moved relative to one another. The roller chimes have an L-shaped cross section each with an out-wardly extending horizontal web or leg and with a vertical leg extending from the outer end of the horizontal leg in either the upward or downward direction depending upon the location of the chimes.

1~6788 'rhe sh~lpe of t]le roller chime is of special signifi-cance. The gripping device for lif-ting and carrying the drum grasps with its -tong arms under the hori%ontally outwardly pro-jecting roller chime leg and ],ehind the vertically extending leg. Accordingly, the vertical leg of the upper ro]ler chime, that is, the chime adjacent the drum hcad, extends upwardly from the horizontal leg while the vertical leg of the lower roller chime, that is, the chime adjacent the bottom end of the drum, is directed downwardly from the horizontal leg. Due to the varying material distribution in the drum body, difficulties occur in the formation of the roller chimes. In the region of the dividing seams in the mold, the material of the extruded parison is doubled when the mold halves are moved to the closed position as the parison is clamped in place. During the blow-ing process as discribed above, the parison is stretched and those regions which move away from the squeezed seam become sig-nificantly thinner. In the formation of the roller chimes in the upper and lower displaceable parts of each mold half, dif-ferent volumes of material are available. As a result, due to 20- the larger amount of the material in the region of the dividing seams, the displaceable mold parts cannot close completely and, thus, a satisfactory formation of the roller chimes in the region of the thinner areas becomes impossible. Because of the gripping devices used in lifting and transporting the drums, a satisfactory formation of the roller chimes is required.
It is the primary object of the present invention to form roller chimes of L-shaped cross section which extend out-wardly from and are formed out of the drum body and provide a uniformly shaped groove for gripping the drum taking into con-sideration the unequal material distribution within the parisonas it is blown outwardly within the openable molds.
In accordance with the present invention, while the 1~96788 depth of the groove formed by the roller chime is uniform about the entire circumference of the drum, the wall thickness of the horizontal leg decreases from the dividing seams in the mold for an angular extent of 90 until the horizontal leg thickness reaches a minimum corresponding to the ,hickness of the drum body and then increases steadily to the region of the next mold dividing seam. The horizontal legs of the roller chime adjacent the head end of the drum where the region of largest material accumulation occurs are widened, that is, in the radial direction from the drums, by providing indentations in the head end dir- !
ected toward the interior of the drum.
For producing the desired horizontal leg thickness, the part of the mold which forms the outer surface of the hori-zontal leg has a wave-like contour with the wave troughs arranged in the region of a larger accumulation of the material and the wave crests located in the region of the lesser material accumulation. Accordingly, the movable mold parts of each mold half can be closed completely without pressing the larger mat-erial volume into the interior of the drum. Furthermore, the shape of the mold part forming the outer horizontal leg surface guarantees the uniform or constant height of the vertical leg of each roller chime around its circumference.
To enlarge the cooling surface and thereby reduce damaging shrinkage stresses in the regions of the larger material accumulation, at such locations the horizontal legs of the roller chimes are widened adjacent the head end of the drum by forming indentations into the head end with the indentations opening to the outer surface of the drum. The indentations are formed around and downwardly from the bungs located in the mold divid-ing seams. These bungs, in turn, direct additional materialinto the regions of the mold dividing seam when the blow mandrels are moved apart during the step of closing the blowing mold.

10~6788 The various features of novelty whic]l characterize the invention are pointed out with particularity in the clairns annexed -to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
In the drawings:
Fig. 1 is a side view of a closed head drum having a roller chime adjacent each of its head end and bottom end;
Fig. 2 is a developed projection of a drum half as shown in Fig. 1 with the development illustrated in a simplified manner and in a reduced scale as compared to Fig. l; and Fig. 3 is a top view of the closed head drum shown in Fig. 1 and also illustrated on a reduced scale.
In Fig. 1 a closed head drum 3 is shown in the verti-cal position, that is, with its axis vertical. The drum body 3 is formed in a mold consisting of mold halves which can be moved between open and closed positions. Additionally, each mold half has mold parts movable in the axial direction of the drum.
Roller chimes l, 2 are formed radially outwardly from the drum body by moving the mold parts in the axial direction after the mold is closed and the parison of thermoplastic material is blown outwardly against the interior surfaces of the mold halves.
Each of the roller chimes 1, 2 as viewed in Fig. 1, has a hori-zontally extending leg extending radially outwardly from the outer surface of the drum body 3 and a vertically extending leg in generally parallel relation with the axis of the drum and extending from the horizontal leg toward the adjacent end of the drum. In other words, the vertical leg of roller chime 1 extends toward the top or head end 4 of the drum while the ~oq6788 vertically extend;ng 1eg of roller chime 2 extcnds downwardly toward the adjacent bottom end of the drum.
As can be seen in Fig. 1, the head end 4 and hottom end 5 of the drum body each project axially beyond the roller chimes 1, 2 so that the roller chimes are protected when the drums are stacked. P~ungs 6, ~ are formed on the opposite sides of the drum head in recesses or indentations 8 formed into the head end.
In Fig. 2 which illustrates -the development of one drum half extending between the dividing seams, the roller chimes 1, 2 have vertical legs 10. Dotted lines 9 designate the face of the horizontal leg within the groove or recess formed by the roller chime and the adjacent surface of the ad~acent surface of the drum body. In other words, in the roller chime 1 the surface 9 faces upwardly while in the lower roller chime 2 the surface 9 faces downwardly. The solid line 12 designates the outside surface of the horizontal leg, that is, the downwardly facing surface of the upper roller chime 1 and the upwardly facing surface of the lower roller chime 2.
20 - The outer surfaces 12 face toward the center of the drum. The opposite vertically extending lines on the left and right of the half drum body 3 in Fig. 2 are the mold dividing seams in which region is the largest accumulation of material in the roller chimes 1, 2. In accordance with the design of the surface of the blowing mold which define the roller chimes, the wall thick-nesses of the horizontal legs of roller chimes 1, 2 decrease steadily from one mold dividing seam toward the center of the developed mold half where the wall thickness reaches a minimum and then steadily increases to the opposite end mold dividing seam.
The height of the vertical legs 10 projecting upwardly or downwardly from the inner surface 9 of the horizontal legs is 10~67~8 constant around the entire circumfercnce of the drum, the bottom of the grooves formed by the roller chimes and the outer surface of the drum body is indica-ted by -the dotted surfaces 9 of the horizontal legs. If the entire development of the drum were illustrated, a wave-like pattern of l:he lower face of the hori-zontal leg of the upper roller chime 1 or the upper ~ace of the horizontal leg of the lower roller chime 2 would result and view-ing the upper chime 1, the wave troughs would be located in the region of the mold dividing seams. ~imilarly, the wave crests would be located in the regions of the least accumulation of material, that is, where the parison is subjected to the greatest stretching action when it is blown outwardly against the mold surface.
In Fig. 3, the horizontal leg of the upper roller chime 1 has a wider portion 11 in the region of the largest accumula-tion of material adjacent the bungs 6, 7 due to the formation of the recesses or indentations 8 directed into the drum.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the inven-tion may be embodied otherwise without departing from such principles.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
l. A closed head drum formed of a thermoplastic material parison blown within a mold openable horizontally along a vertical plane and comprising a head end, a bottom end spaced from said head end, and at least one side wall formed integrally with and extending between said head and bottom ends and forming the lateral closure of the drum, said side wall having a pair of circumferentially spaced mold dividing means located on the openable vertical plane, at least one roller chime formed integrally with and extending around said side wall, said roller chime being L-shaped and comprising a first leg extending radially outwardly from said side wall and a second leg extending from and transversely of the radially outer end of said first leg so that said second leg extends generally in the same direction as said side wall, said second leg is spaced radially outwardly from the outer surface of said side wall and forms, in combination with said side wall and said first leg, an annular recess extending circumferen-tially around the drum, and said first leg having a variable thickness extending in the direction between the head end and bottom end of the drum with the maximum thickness being located at the dividing seams and the minimum thickness thereof located spaced between the dividing seams.
2. A closed head drum, as set forth in claim 1, wherein the minimum thickness location of said first leg is equidistantly spaced from the dividing seams.
3. A closed head drum, as set forth in claim 1, wherein at least one indentation is formed in said head end adjacent and opening to the circumferential periphery thereof.
4. A closed head drum, as set forth in claim 3, wherein said roller chime is located adjacent said head end and said first leg of said roller chime has a greater dimension radially outwardly from the outer surface of said side wall in the angular range of said indentation then the radially extend-ing dimension of said first leg for the remaining circumferen-tial extent of said chime.
5. A closed head drum, as set forth in claim 3, wherein two said chimes are formed in said side wall,one adja-cent said head end and the other adjacent said bottom end, two said indentations are formed in said head end with said indenta-tion located diametrically opposite one another at the location of the mold dividing seams.
6. A closed head drum, as set forth in claim 5 wherein said second leg of each said annular recess has the same height from said first leg for the circumferential extent of said annular recess.