FI77600B - VAKUUMKALIBRERINGSANORDNING. - Google Patents

Abstract

Vacuum sizing device has a modular construction consisting essentially of sets of pairs (32) of upper and lower sizing elements arranged end to end to define a passageway (26) having a cross-sectional shape and size corresp. to that required for a plastic extrusion (24) from a die (22). The elements are clamped between upper and lower backing members (20,30) held together by T-headed bolts (76). In order to maintain the extrusion (24) in close contact with the internal walls of the sizing elements, the walls are broken by strategically placed vacuum openings which merge within the element bodies and open into vacuum chambers. These chambers have screw threaded ports communicating with the exterior which can be connected to a vacuum source by couplings (50). The elements also contain cooling chambers through which a cooling fluid can be circulated for cooling the extrusion. The vacuum sizing device is for sizing extruded profiles such as PVC window frames. By using a modular structure, the mfg. costs of the device are considerably reduced as the element pairs are relatively small, identical pieces of metal which are ideally suited for computer controlled machine tool mfr. Also, the device can be dismantled and transported and cleaned with ease.

Description

1 77600

VACUUM CALIBRATION DEVICE - VACUUM CALIBRATION SYSTEM

The invention relates to a vacuum finishing device used in the manufacture of plastic extrudates to cool and finish the extrudate immediately downwards from the extrusion nozzle. Vacuum finishing devices are also known as calibration devices, but to simplify the explanation, the previous term is used here.

The plastic extrudate exiting the extrusion nozzle is generally in a relatively hot and malleable state, and as a result, it generally does not retain the shape provided by the extrusion nozzle unless special precautions are taken to keep the extrudate in that shape. In some cases, deformations are not important (e.g., when the extrudate is to be blown), but in many cases, precise adjustment of the shape profile 15 and finishing of the extrudate is necessary. Accurate matrices with "fingers" that are in contact with the hot extrudate as it cools in air are often used. However, these devices need skilled personnel to position their fingers accurately and constantly monitor the dimensions of the extrudate-20 below the matrix to ensure that adequate control is maintained. The matrix must also keep the extrudate at a relatively long distance to ensure that control is maintained until the extrudate has completely cooled.

25 Vacuum finishing equipment was developed for extrudates that must adhere to precise profile finish and shape tolerances. One example of a situation where such precise control is required is the manufacture of plastic extrudates for use as plastic window frames. The September 1981 edition of "Modern Plastics" describes on page 14 an example of a conventional vacuum finishing device (referred to herein as a "calibration device") for making PVC window frames.

35 2 77600

A conventional vacuum finisher is a relatively massive and cumbersome structure, typically about 0.9 to 1.2 m long and weighing tens of kilograms and. Extending through the structure are ducts through which the nozzle-5 junction passes and whose cross-sectional shape is precisely dimensioned to correspond to the desired final external dimensions of the nozzle. The structure forms an upper part and a lower part which meet on the connecting line, forming a duct so that one longitudinal part of the duct forms a lower part of the structure, while the upper part delimits the other longitudinal part of the duct. The two parts are bolted together when the device is in use so that the parts work together, strictly limiting the distance.

It is important that the surfaces that delimit the walls of the ducts are carefully machined and provided with suitable surface coatings because of any defects. on the surface of the duct wall pass into the extrudate. Vacuum openings are generally also formed in the walls of the duct to form a connection to an external vacuum source so that the mouth baffle passing through the duct 20 remains positively held by the vacuum against the wall surfaces. Again, these gates must be carefully machined to avoid or at least minimize scratching of the extrudate.

; Cooling water ducts are generally also provided in the upper and / or lower part of the finishing device 25 so that cooling water can be circulated through the device to promote rapid curing of the plastic material.

Conventionally, the upper and lower parts of a vacuum finisher are of unitary construction, which are made in one piece. It is important that there is sufficient time and skill to manufacture these parts. Typically, a plurality of longitudinal ducts must be traversed along at least one section along their entire length (about 0.9 to 1.2 m or more). Transverse ducts joining these longitudinal ducts often have to be drilled horizontally through the sections, and the corresponding ducts must be closed at their ends, as is necessary to form a halter 3 77600 ltu route for cooling water or vacuum, as the case may be. It is, of course, clear that not all vacuum finishing devices are the same. In most cases, the cooling ducts and vacuum ducts must be located according to the profile of the special extrudate to be specially prepared. In general, larger parts of the profile require more cooling and more vacuum than lighter (thinner) parts.

It follows from the above that such conventional vacuum finishing devices are technically very difficult to manufacture and are therefore extremely expensive. At the same time, they are large and bulky and can only be moved by multiple people or with a lifting device. Not only does this make the handling and installation of the devices 15 inconvenient, but it can cause extreme difficulties in abnormal situations, eöim. in the event of a power failure, in which case the extrudate may cool in the duct of the vacuum finisher.

In this case, it is extremely small to separate the parts 20 of the device from each other and to remove the extrudate; in fact, it may be impossible to separate the parts of the device when the extrudate has an outwardly widening profile.

It is an object of the present invention to provide an improved vacuum finishing apparatus.

The invention relates to a vacuum calibration device comprising longitudinally extending ducts thereof, the cross-sectional shape and size of which correspond to the desired shape and size of the plastic extruded profile to be calibrated in the device, the device comprising: a plurality of upper and lower pair of calibration elements; between them the longitudinal part of the duct and the pairs of elements are arranged at the ends and adapted to co-operate with each other, which elements together form the whole of said duct, each calibration road element being a single component and at least some of them provided with vacuum members communicating with the duct.

The invention is characterized in that upper and lower support members are arranged above and below the pairs of calibration elements 4 77600 elements, which extend over the entire length of the duct, that the members detachably fasten the support members to each other in connection with and hold the calibration element pairs together. each calibration element is provided with a coolant opening communicating with the coolant chamber in the element and with vacuum openings which open onto a surface of the element which is accessible from outside the device.

It is clear that an important advantage of this device over the prior art is that the finishing duct device forms a number of individual finishing elements which can be individually manufactured to form the exact desired shape of the cooling openings and the cooling openings. For ease of manufacture, the lower finishing elements (i.e., the elements closest to the lowest support member) are preferably all identical to each other. . and the upper finishing elements are also ‘. identical to each other. This greatly facilitates the fabrication of the elements themselves, as only two-shaped elements are required. Normally, it is not possible for all elements (both upper and lower elements) to be identical to each other unless the nozzle to be finished is: symmetrical with respect to the horizontal plane. All finishing elements that are identical can be conventionally made with a computer-controlled machining tool, which greatly reduces the manufacturing cost of the finishing device.

For ease of understanding of the invention, reference will now be made to the accompanying drawings, which illustrate a preferred embodiment of the invention by way of example, and in which Figure 1 shows a perspective view of a vacuum finishing device V according to the invention; Figure 2 shows an exploded perspective view of a finishing element pair; and Tue 77600 Figures 3 and 4 show vertical sections along lines III-III and resp. IV-IV from Figure 2.

Reference is first made to Figure 1, in which the vacuum finisher is generally indicated by reference numeral 20 and the device 5 is shown below the plastic mouth press machine shown in broken lines 22. A plastic extrudate that continuously protrudes from the nozzle end of an extrusion machine (not shown) is indicated by reference numeral 24. The device 20 has ducts extending longitudinally through the device and 10 having a cross-sectional size and shape corresponding to the desired profile, size and shape of the extruder 24. One end of this duct is shown in Figure 1 at the bottom left, and the ducts themselves are indicated by reference numeral 26. The extrudate 24 protrudes into the duct 26 at the right-hand end of the finisher in Figure 1 and passes through the duct at a speed depending on the operating speed of the extruder 22. Typically, a traction device and a separation device (not shown) is. . arranged below the vacuum finisher 20. The extrudate exiting the duct 26 is shown in broken lines 24 ', and the cross-sectional shape of the extrudate is shown in solid lines.

"... The finishing device consists of a series of individual • finishing element pairs fastened between the upper::: and lower support members. In Fig. 1, the support members 25 are denoted by reference numerals 28 and 30, respectively, and the last telegraph element pairs between support members are generally denoted by reference numeral 32. in a particular embodiment, there are eight pairs of finishing elements, and the end faces of the elements in one pair are shown at the left end of Figure 1. The lower element in each pair (i.e., the elements closest to the support member 30) are all: identical to each other, and the upper elements organ 28) are identical to each other but different from the lower elements.

35 Figure 2 shows one such pair of finishing elements, the elements shown separately. Figures 3 and 4 show cross-sections of the same two elements, but shown in the positions they have in the assembled device. In these figures, the elements are denoted together by reference numeral 32 (the same general reference numeral as in Fig. 1), while the upper and lower elements are denoted individually by reference numerals 34 and 36.

It is best seen in Figures 3 and 4 that the two elements 34 and 36 are shaped to form a longitudinal portion of the duct 26 passing between them between the finishing device 26. In the assembled device, the pairs of elements are arranged end to end and co-operate with each other to form the entire duct 26. With further reference to Figures 3 and 4, it will be seen that each of the elements 34 and 36 is substantially L-shaped in general cross-section, and that the elements are nested together to form a space forming part of the duct 26. The surfaces in the respective elements forming this space are shaped, especially in extrusion, according to the desired profile, and are uniform in cross-section along the entire length of the element.

: Reference is now made again to Figure 2, which shows that each of the elements 34, 36 is generally square when viewed from above, and their side length can be, say, 10 cm. . The element 36 has an upper surface 38 which includes a lower horizontal surface 38a, an overhang surface 38b and a horizontal upper surface 38c. The surface 38b and a portion of the surface 38a form portions of the duct 26, and the extrudate passes through these ducts 26. To keep the extrudate in close contact with these surfaces (and the corresponding surfaces of the element 34), vacuum openings are formed on the surfaces to be connected to an external vacuum source. From the particular embodiment described, it can be seen that the surface 38a of the element 36 is provided with three rows of 35 small circular openings, indicated by reference numeral 40. The openings extend substantially parallel to the length of the channel 36 and are perpendicular to the surface ti 7 77600 38 in a far right as seen in Figure 2, located at the junction of said surface and the vertical surface 38b. In addition, three slit-shaped vacuum openings, indicated by reference numeral 42, are formed near the left (downward) end of the element 36 5 (viewed in the direction of movement of the extrusion along the channel 26). These slits are arranged substantially parallel to each other and at right angles to the rows of openings 40.

The slits 42 extend downwardly into the body 10 of the element 36 and open into the vacuum chamber 44, which opens below the element 36. The chamber 44 is shown in section in Figure 3, and it can be seen that the chamber includes an upwardly projecting portion 44a below the upper horizontal surface portion 38c of the surface 38.

This part of the vacuum chamber is not actually used in the application shown 15, but is designed so that additional vacuum openings can be easily formed by drilling through the surface 38b and into the vacuum chamber, if any. : openings are considered necessary. The vacuum openings 40 communicate with the vacuum chamber 44 through elongate ducts 20 46 (Figure 3) which are drilled through the body of the element above the chamber 44 and closed at their ends. These ducts communicate with the slits 42, and the openings 40 extend vertically downwardly into these ducts. In addition, the openings 40, which are directly above the chamber 44, extend down into the chamber itself.

A screw threaded opening is formed on the other side of the element 36, accessible from outside the mounted finisher, and communicates with the chamber 44. This opening may be provided with a screw thread connection as indicated generally by reference numeral 50 in Figure 1, and may then be connected with a suitable connection to the vacuum source.

Referring again to Figure 2, it is seen that the vacuum chamber 44 occupies somewhat less than half of the total length of the finishing element 36, and that a second, substantially similar chamber is formed adjacent the chamber 44. This second chamber, indicated by reference numeral 52 in Figure 2, is a coolant chamber through which coolant or other coolant can be circulated while the finisher is in use. The chamber 52 5 is substantially the same shape as the chamber 44, but is provided with two openings, denoted by reference numerals 54 and 56, which open to respective opposite sides of the element 36. These openings are also screw threaded to connect connections similar to connections 50 10 in Figure 1, and in this case one connection is connected to the cold water storage and the other to a return line, typically a jet cooler, to evaporate the heat removed from the finisher. In the case of a cooling chamber, the connections are, of course, made to the front and back of the finisher in Figure 1 (connections 50).

Figure 4 shows a coolant chamber 52, and two openings 54 and 56; the arrows in Figure 4 are intended to show the circulation of coolant through the chamber.

Reference is now again made to Figure 2, in which the finishing element 20 has vacuum and cooling chambers / denoted by reference numerals 44 'and resp. 52 ', which are substantially the same as the cooling chambers 44 and 52 in the element 36. The chambers in the element 34 are shown from below. The slit-like vacuum openings, in connection with the vacuum chamber 44 ', are indicated by reference numeral 42, and the rows of vacuum openings corresponding to the openings 40 are indicated by reference numeral 40'. The longitudinal ducts connecting the chamber 44 'and the openings 40' are shown in particular by the dashed lines in the element 34 and are denoted by reference numeral 58. The plugs 20 which close the ends of these ducts are denoted by reference numeral 60. As well as the element 36, the vacuum chamber 44 'is provided with a vacuum port, indicated by reference numeral 48', and the vacuum chamber 52 'is provided with inlet and outlet ports, designated by reference numerals 54' and resp. 56 '. 35 As previously indicated, all the lower finishing elements of the finisher (Figure 1)

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9 77600 in pairs 32 are identical to each other and all upper elements are likewise identical to each other. Further, the respective upper and lower elements are identical whenever there are differences in the form of the mouth-5 mold to be finished. Thus, the upper finishing elements (e.g., element 34) are specifically shaped at their inner surfaces to form a generally T-shaped formation 62 corresponding to an elongate channel in the extrudate and an inwardly projecting portion 64 corresponding again to the channel of the extruder cross member 10. In the latter case, a series of parallel vacuum openings 66 extend from the outer surface of this part into the vacuum chamber 44 'to help ensure the formation of this part of the extrudate. In all cases, despite these differences, all finishing elements are substantially similar and are made from standard metal blanks by a computer-controlled machine tool. These types of machine tools can be adjusted to produce. . automatically an exact copy of any part, which *: means that once the machine has been adjusted, the parts 20 can be formed very cheaply. The small changes required to machine the outwardly projecting portions 62 and 64 at the elements 34 in place of the flat surfaces of the element 36 can be lightly programmed into the machine. Thus, it is obvious that the vacuum finishing device according to the invention can be manufactured at about one tenth of the cost of a conventional device.

It should also be noted that the special shape of the vacuum openings and cooling chambers shown in Figures 2-4 is only one example, and that many variations are possible. For example, when it is considered most cost effective to make all finishing elements substantially similar, in some cases it may be desirable to use different elements at different points along the finishing device for different extrudates.

For example, in one case, it may be desirable to form a large area of vacuum openings in the upper portion of the finisher, possibly without cooling, and provide cooling but no vacuum at the opposite end of the apparatus. This can easily be achieved by arranging differently shaped finishing elements in different places. In one case, it may alternatively be sufficient to simply close or omit some of the openings in some of the finishing elements as required. In other cases, it may be desirable to form additional vacuum openings at a particular location in the finishing element or to provide additional cooling. Again, this can be accomplished by suitable simple deformations. For example, instead of providing each finishing element with two chambers, as shown in the application example, four chambers, say two vacuum chambers and two cooling chambers or three cooling chambers 15 and one vacuum chamber or any shape, may be formed for a particular profile to be extruded.

It will be appreciated from the foregoing that the finisher of the present invention allows extensive cooling and vacuum conditions to be established in each particular finisher and at the same time allows conditions to be changed easily by simply changing a particular finishing element, pair of finishing elements or group of elements. The finishing elements are preferably all assembled so that each pair of elements is generally similar in size to any other pair of elements to allow them to be replaced.

Reference is now again made to Figures 3 and 4, in which the support members 28 and 30 are shown in broken lines, but it can be seen from Figures - 30 that the finishing elements fit the hollow channels indicated by reference numerals 28a and 30a in the respective support members. Thus, each element resting on the respective finishing. Interior of the channel support member side, and a rubber seal is disposed between the channel and the finishing element to the UL-35 CLS. In Figures 3 and 4, the respective seals are shown by reference numerals 68 and 70. The seals form a 11 n 77600 barrier for air leaks into vacuum chambers or cooling water leaks from cooling chambers. Each finishing element is bolted to the corresponding support member with four seat-head screws, as shown at 72 and 74 in Figure 2. It can be seen from said figure that each element is provided with four openings, one at each corner of the element; each opening has one seat in a corresponding screw which is screwed into a corresponding threaded recess in the respective support member. Thus, the upper finishing elements (such as element 34) are all bolted to the upper support member 28, while the lower finishing elements are bolted to the member 30.

Referring now to Figure 1, two support members are releasably connected together by T-terminal bolts 76 passing through openings in the protruding side portions of the upper support member 28 and screwed into screw-threaded openings in respective portions of the support member 30. The bolts have protrusions (not shown) that press against the top surface of the member 28 so that when all the bolts 20 are tightened, they effectively compress the two support members together with the finishing elements therebetween.

"· However, when removing the bolts, the upper support member 28 can be lifted out of the lower support member and carries the upper finishing elements (such as element 34) with it, leaving the lower elements bolted to the lower support member. In this way, the pairs of finishing elements are all separated at the same time: by providing a recess on the surfaces of the elements, which limits the duct 26. In the illustrated embodiment, this enables access to an extrudate compressed in the duct 26 (e.g. as a result of a power failure) as the extrudate detaches from the protruding parts 62 with the upper finishing elements. However, it should be borne in mind that this may not be possible with some extruders, which may have 12 77600 attached to both the upper and lower finishing elements.

Figure 1 shows the shape of the cross-sections of the support members 28 and 30. Both members have a constant cross-sectional shape along their entire length, and both have slots of corner portions extending along their outer surfaces, such as slits 78 and 80 in the support member 28. The slots can be used to receive support handles 82 having outer ends (shaped These handles 10 allow the entire finisher to be carried with the bolts 76 in place or, with the bolts removed, allow the upper vacuum member 28 and the upper finishing elements to be lifted out of both elements as a single unit.

It should be emphasized that the foregoing description relates, by way of example, to a particular embodiment of the invention and that many modifications are possible within the broader scope of the invention. A number of possible modifications have been specifically explained above, and it should be emphasized again, 20 that the specific shape of the described refrigeration devices and vacuum chambers is given by way of example only, and that these "may vary.

; The finishing elements in the finisher are preferably, but not necessarily, assembled so that they all have the same general size and shape. The finishing elements are preferably made of aluminum (for lightness) and coated on treads with nickel, but: again this is not essential. Examples of other metals that can be used are brass and stainless steel, although stainless steel needs a hard coating or chrome coating. at least at the points of consumption.

In the illustrated embodiment, the finishing elements are shown bolted to the respective support members 28 and 30, but this is again not essential, although some kind of fastening device (e.g. support) is desirable between the fastening elements and the support members. Bracket-

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The 13 77600 members may also be aluminum, but are preferably made of steel.

Claims (10)

A vacuum calibration device (20) comprising longitudinally extending ducts (26) having a cross-sectional shape and size corresponding to a desired shape and size of a plastic extruded profile (24, 24 ') to be calibrated in the device, the device comprising: a plurality of upper and pairs (32) of lower calibration elements (34, 36), each pair of elements 10 being shaped to form a longitudinal portion of the duct therebetween, and the pairs of elements being arranged end to end and cooperating with each other to form said entire duct, each calibration-15 the element is a single component and at least some of them are provided with vacuum members in communication with the duct, characterized in that the upper and lower pairs (32) of the pairs (32) of calibration elements (34, 36) *: * below are arranged upper and lower support members (28, 30) extending along the entire length of the duct (26) so that the members (76) releasably fasten the support members (28, 30) to each other to keep the drops of the calibration element-1 cooperating with each other , and that each calibration element (34, 36) is provided with a coolant opening (54, 54 ') communicating with the coolant chamber (52, 52') in the element (36 or 34) and with vacuum openings (48, 48 ') which the openings (48, 48 'and 54, 54') open onto a surface of the element (36 or 34) which is accessible from outside the device (20). Device according to Claim 1, characterized in that the pairs of calibration elements (32) are modular in such a way that each pair has the same general shape. Device according to claim 1, characterized in that each upper calibration element (34) is removably attached to the respective support member (28), and each lower calibration element (36) is removably attached to the corresponding lower support member (30). , while the calibration elements in each pair (32) are free from direct attachment to each other. Device according to Claim 3, characterized in that at least some of the calibration elements (34 or 36) have a vacuum chamber (44 'or 44) which communicates with the vacuum openings, and that the chamber (44' or 44) opens to the rear of the element and is closed by an associated support member (28 or 30) by means of an intermediate seal (68 or 70). Device according to Claim 4, characterized in that the vacuum chamber (44 ', 44) communicates with the vacuum openings via at least one duct (46, 58) which extends longitudinally through the calibration element and the ends of which are closed (60). Device according to claim 3, characterized in that each liquid chamber (52, 52 ') formed in the calibration element (36 or 34) opens to the rear of the element and is closed by an associated support member (30 or 28). with seals (70 or 68). Device according to claim 3, characterized in that each calibration element (34 or 36) is provided with a coolant chamber (52 'or 52) and a vacuum chamber (44' or 44), the chambers being arranged in parallel and substantially similar in shape , wherein the vacuum chamber (44 '30 or 44) communicates with the vacuum openings, and each chamber opens to the rear of the element and is closed by an associated support member (28, 30) with intermediate seals (68, 70). Device according to one of Claims 1 to 7, characterized in that the support elements (28, 30) are designed so as to protrude from the calibration elements (34, 36) on each side of the device (20), and that the removable fastening device C? 6) comprises bolts projecting through protruding parts of the support members on both sides of the device, releasably connecting the members (34, 36) together. Device according to one of Claims 1 to 8, characterized in that each fastening element (28, 30) has an outer surface with two parallel slots (78, 80) having an angular cross-section which extend along their outer surfaces and are adapted to receive correspondingly shaped end portions of the handles (82) to facilitate lifting of the device (20) and the securing member (28 or 30). Device according to one of Claims 1 to 9, characterized in that each calibration element (34 or 36) is made of aluminum and is coated with nickel on its treads.