Title of Invention

"A MOLDING SYSTEM HAVING A PLURALITY OF MOLD BLOCKS"

Abstract

A molding system including a plurality of mold blocks A molding system (1) including a plurality of mold blocks (9) which move along a molding path to form double wall plastic pipe having an outer wall with corrugations which set outside diameter of the pipe and an inner wall around a pipe bore through the pipe, each mold block having profiled face which determines shape of the pipe, said profiled face including a trough, a crest mounting portion and a crest forming part characterized in that said trough (13) and said crest mounting portion (12) are formed in and integral with said mold block and said crest mounting portion is positioned inwardly of the trough (13) with said crest mounting portion (12) detachably and selectively receiving said crest forming parts (15, 23) which are of radial different dimensions for reconfiguring said profiled face between a first and a second face profile to change both depth of the corrugations and diameter of the bore through the pipe without varying the external diameter of the pipe.

Full Text

The present invention relates to a molding system having a plurality of mold blocks. FIELD OF THE INVEgnPION The present invention relates to a pipe molding system including a mold tunnel formed by moving mold blocks in which the shape of the pipe can be varied without having to replace the mold blocks. BACKGRUND OF THE INVENTION In a traditional pipe molding apparatus of the type using mold blocks which move along a molding path to form what is known as a moving mold tunnel, the only way to change shape of the pipe is to replace the pipe forming mold block sections. This is very costly in that these mold block sections themselves are extremely expensive because they include features such as vacuum openings, cooling channels etc. required in the fonnatxon .of the pipe. However, according to known pipe forming devices using moving mold tunnels it is a requirement to have interchangeable mold block sections to produce different shapes and sizes of pipes. Different job applications require different pipe strengths even though the same diameter of pipe may be required for each job application. It would seem that a simple way of dealing with this situation is to vary the wall thickness of the pipe to make the pipe either stronger i.e., more rigid through increased wall thickness or to make the pipe softer i.e., more flexible through decreased wall thickness. However, industry standards dictate that a certain wall thickness is required which does not allow thinning of pipe walls for making a pipe more flexible. constant thickness of the pipe walls. As a result of the immediately above aspect of the present invention a single molding system without the requirement for mold block replacement can be used to make either a stronger i.e., more rigid pipe or a softer i.e., more flexible pipe. BRIEF DESCRIPTION OF THE DRAWINGS The above as well as other advantages and features of the present invention will be described in greater detail according to the preferred embodiments of the present invention in which; Figure 1 is Figure 1 is a schematic view of a pipe molding apparatus used in a pipe mold system according to a preferred embodiment of the present, invention; Figure 2 is a further schematic view of the pipe .molding region of the apparatus of Figure 1 with the mold blocks set up in a first face profile condition to produce a relatively flexible length of corrugated pipe; Figure 3 is a further schematic view of the molding region of the apparatus of Figure 1 with the mold blocks set in a second face profile condition to produce a relatively rigid length of corrugated pipe; Figure 4 is a front view of one of the mold block sections with the apparatus set up in the Figure 2 condition; Figure 5 is a front view of one of the mold block sections of the apparatus set up in the Figure 3 condition; and Figure 6 is a sectional view through the mold block section of Figure 4. DETAILED DESCRIPTION ACCORDING TO THE PREFERRED - EMBODIMENTS OF THE PRESENT INVENTION IN WHICH; Figrure 1 shows a pipe molding apparatus generally indicated at 1. This pipe molding apparatus includes an extruder 3 which provides molten plastic through plastic flow channels of an extruder die 5 to a moving mold tunnel generally indicated at 7. The moving mold tunnel is formed by a plurality of mold block sections 9 to each side of the mold tunnel. These mold block sections have profiled i.e., corrugated faces to receive plastic from the two channel mouths 6a and 6b of the die equipment located within the mold tunnel. The plastic emanating from channel mouth 6a flows into the troughs in the faces of the mold blocks to form an outer corrugated wall of the pipe. The plastic emanating through channel mouth 6b forms an inner pipe wall bordering a central bore through the pipe. The molten plastic of the inner pipe wall is set to shape and cooled by a cooling plug 11 internally of the mold tunnel. Figure 2 of the drawings shows the apparatus set up to produce a double wall pipe 18 having an inner pipe wall 19 and an outer corrugated pipe wall 21. Each of the mold blocks 9 includes a trough 13 to shape the corrugations 21 on pipe 18. These corrugations set the outside diameter of the pipe. Each of the mold blocks further includes a mold block crest between each of the troughs 13. In accordance with a preferred embodiment of the present invention the height of this mold block crest is variable to vary the depth of the corrugations. This variance in turn produces a bore diameter change in the pipe with little or no change to the wall thicknesses of the pipe. Again referring to Figure 2 of the drawings, each of the mold block sections 9 has a mounting surface 12 on each side of each of the troughs 13 in the; mold block section. This mounting surface 12 is adapted to interchangeably receive different mold block crest forming attachments. In Figure 2, crest forming attachments 15 are mounted to each of the mold block mounting surfaces 12. Now turning to Figure 3 it will be seen that the mold block sections 9 and in particular the profiled faces of the mold block sections have been reconfigured from the Figure 2 faie profile to a different face profile. This is done by the attachment of crest forming attachments 23 to the mounting surfaces 12 of the mold block sections in the Figure 3 set up. Crest forming attachments 23 of Figure 3 are substantially longer than crest forming attachments 15 of the Figure 2 set up. Furthermore as will be seen in Figure 3 of the drawings the pipe generally indicated at 27 formed using the Figure 3 set tap includes an outer wall formed by corrugations 31 which are substantially taller than the corrugations 21 of pipe 18 from Figure 2. Furthermore, in Figrure 3 the bore diameter of the pipe 27 defined by the inner pipe wall 29 is substantially smaller than the bore diameter through pipe 18 defined by inner wall 19 in Figure 2. Accordingly, pipe 27 of Figure 3 is a substantially stronger or more rigid pipe than pipe 18 of Figure 2. However, the overall external di.ameter of the two pipes is identical. Furthermore, the wall thickness of pipe 18 is essentially the same as the wall thickness of pipe 29. The reconfiguration of the pipe from the Figure 2 pipe shape to the Figure 3 pipe shape is achieved simply by the use of interchanageble face attachments of different heights at the mold block faces without having to replace the mold block sections. In addition, it will be noted in Figure 3 that a smaller diameter cooling plug 25 has replaced the larger diameter cooling plug 11 to form the smaller bore pipe 27 of Figure 3. Figures 4 and 5 of the drawings show a number of preferred features of the present invention. In particular. Figure 4 shows a mold block section 9 provided with the shorter crest forming members 15 supported by the mounting surfaces 12 to either side of the troughs 13 in the face of the mold block sections. Figure 5 on the other hand shows the taller crest forming members 23 fitted to the mounting surfaces 12 to either side of the trough 13 in the profiled face of mold block section 9. A number of other features can be seen in Figures 4 and 5 of the drawings. In particular, these drawings show that the mold block sections include sophisticated vacuum and cooling channels required to first shape and then cool the plastic at the faces of the mold blocks. The interchangeability of the face attachments at the mounting surfaces 12 of the mold block sections in no way impedes or affects either the vacuum or the cooling channels- Figures 4, 5 and 6 also show a particular means of replaceably mounting the face attachments to the mold block sections. This means comprises a bracket 35 having forwardly extending arms 37 and 39 to opposite ends of the bracket. The mounting surface of the mold block section is provided away from the pipe forming region with a bore 40 to receive a threaded bolt 41. Also provided in the mold block section is a recess 10 for receiving the leg 39 of bracket 35. A similar recess 16 is provided in the face attachment 15 to receive the leg 37 of bracket 35. As will be appreciated from the description above the bracket is easily secured to and removed from the mold block to secure face attachment 15 or to replace it with face attachment 23 which has a corresponding bracket receiving recess. Although various preferred embodiments of the present invention have been described in detail, it will be appreciated by those skilled in the art that variations may be made without departing from the spirit of the invention or the scope of the appended claims. We claim: 1. A molding system (1) having a plurality of mold blocks (9) which move along a molding path to form double wall plastic pipe having an outer wall with corrugations which set outside diameter of the pipe and an inner wall around a pipe bore through the pipe, each mold block having profiled face which determines shape of the pipe, said p)rofiled face including a trough, a crest mounting portion and a crest forming part characterized in that said trough (13) and said crest mounting portion (12) are formed in and integral with said mold block and said crest mounting portion is positioned inwardly of the trough (13) with said crest mounting portion (12) detachably and selectively receiving said crest forming parts (15, 23) which are of radial different dimensions for reconfiguring said profiled face between a first and a second face profile to change both depth of the corrugations and diameter of the bore through the pipe without varying the external diameter of the pipe. 2. A molding system as claimed in claim 1, wherein the mold block has a vacuum channel located beneath the trough and the crest mounting portion of the profiled face of the mold block. 3. A molding system as claimed in claim 2, wherein said vacuum claimed is connected to said trough. 4. A molding system as claimed in claim 1, 2 or 3, wherein said crest mounting portion (12) having a projecting shoulder received in a corresponding recess of said crest forming parts to locate said crest forming parts in said mold block. 5. A molding system as claimed in Claim 3 wherein each mold block having opposed ends extending in a length of the mold block for abutting with an opposed mold block and said opposed ends are recessed and has a fastening arrangement securing each crest forming part to said mold block. 6. A molding system as claimed in claim 1, wherein the mold block has a cooling channel located beneath the trough and the crest mounting portion of the profiled face of the mold block. 7. A molding system as claimed in claim 1, wherein the mold block has a recess (10) in the trough and the crest mounting portion of the profiled face and a clip (35) which hooks into the recess (10) and which hooks into a recess of the selected crest forming part (15, 23), the clip (35) securing into of the trough and the crest forming portion of the profiled face at the crest mounting portion (12) by means of a mechanical securing member (41). 8. A molding system as claimed in claim 1, wherein a first cooling plug (11) which is used in the system when the crest forming part (15) is fitted to the crest mounting portion (12) and a second cooling plug (25) which is used in the system in replacement of the first cooling plug (11) when the crest forming part (23) is fitted to the mounting portion (12), the crest forming part (23) being longer than then crest forming part (15) and the cooling plug (25) being of smaller diameter than the cooling plug (11). 9. A molding system as claimed in claim 1, wherein said profiled faces of said mold blocks when configured with the first face profile forming the pipe with a first corrugation depth and a first bore diameter and when configured with the second face profile forming the pipe with a second corrugation depth greater than the first corrugation depth and a second bore diameter less than the first bore diameter. 10. A molding system as claimed in claim 8, wherein said inner wall of said pipe has a wall thickness that remains essentially constant when reconfiguring the profiled faces of the mold blocks between the first and second face profiles. 11. A molding system as claimed in claim 8, wherein said molding path having cooling and shape holding means for the inner wall of the pipe, said means being diameter variable according to which face profile is provided on the faces of the mold blocks. 12. A molding system as claimed in claim 11, wherein said cooling and shape molding means comprises first and second cooling plugs which are interchangeably fittable in said molding path, said first cooling plug having a diameter which is greater than that of said second cooling plug, the first cooling plug being used when the mold blocks have the first face profile and the second cooling plug being used when the mold blocks have the second face profile. 13. A molding system as claimed in claim 3, wherein said mold blocks include first and second mold block sections first and second cooling plugs of diameters differing from one another, securable in a molding tunnel of the system which contains one of said cooling plugs, the mold tunnel receiving a continuous stream of molten plastic to form the pipe over the one of the cooling plugs with an internal bore and a wall having an undulating exterior surface around said bore defined by said mold blocks, said crest forming parts including a first set of crest forming parts and a second set of crest forming parts, the undulating surface defining an external diameter of the pipe; said system when in a first set up condition producing the pipe with a first bore diameter when the said set of crest forming parts are fitted in said mold blocks and said first cooling plug is secured in the mold tunnel; said system when in a second set up condition producing pipe with a second bore diameter different from the first bore diameter while maintaining essentially constant wall thickness of the pipe when the second set of crest forming parts are fitted in said mold blocks and said second cooling plug is secured in the mold tunnel; the external diameter of the pipe remaining constant in both the first and the second set up conditions of the system. 14. A pipe molding system as claimed in claim 13 wherein each crest forming part includes a recess on a back face thereof that receives a projecting shoulder of one of said crest mounting portions to provide alignment of said crest forming parts with said crest mounting portions.

Documents:

2051-delnp-2005-abstract.pdf

2051-delnp-2005-claims.pdf

2051-delnp-2005-complete specification(as filed).pdf

2051-delnp-2005-complete specification(granted).pdf

2051-DELNP-2005-Correspondence Others-(23-03-2011).pdf

2051-DELNP-2005-Correspondence-Others-(13-08-2009).pdf

2051-DELNP-2005-Correspondence-Others-(24-09-2009).pdf

2051-delnp-2005-correspondence-others.pdf

2051-DELNP-2005-Correspondence-PO-(13-08-2009).pdf

2051-delnp-2005-correspondence-po.pdf

2051-delnp-2005-description (complete).pdf

2051-delnp-2005-form-1.pdf

2051-delnp-2005-form-18.pdf

2051-delnp-2005-form-2.pdf

2051-DELNP-2005-Form-27-(23-03-2011).pdf

2051-DELNP-2005-Form-3-(13-08-2009).pdf

2051-DELNP-2005-Form-3-(24-09-2009).pdf

2051-delnp-2005-form-3.pdf

2051-delnp-2005-form-5.pdf

2051-delnp-2005-gpa.pdf

2051-delnp-2005-pct-210.pdf

2051-delnp-2005-pct-220.pdf

2051-delnp-2005-pct-304.pdf

2051-delnp-2005-pct-308.pdf

2051-delnp-2005-pct-409.pdf

2051-delnp-2005-pct-416.pdf