DE8624282U1 - Automatic device for plastic extruders - Google Patents

Description

The invention relates to an automatic device for sorting and adjusting profile bar sections made of thermoplastic material in machines for producing extruded plastic profiles.

It is known that a plant for the continuous production of extruded thermoplastic profiles essentially comprises the following parts: an extruder operating at variable speed, a cooled molding unit which determines the external shape of the profile, a variable speed take-off device which takes off the profile at the correct speed, a cutting device which cuts the profile into predetermined lengths, and finally a device for receiving and delivering the profile lengths after they have been cut.

The extruded sections of plastic material obtained in this way may present dimensional deformations with respect to the desired required shape, i.e. deviations from the correct profile, and also with respect to the thickness of the walls of the profile section.

The external profile of the extruded sections of thermoplastic material is obtained by extruding the material through a die and cooling it and applying it to its external surface

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is calibrated using tools whose shape is complementary to the shape that is ultimately desired.

As regards the thickness of the walls, it must be noted that the thermoplastic material can be stretched or extended to a greater or lesser extent by the pull-out device during the extrusion stage and the softening and/or plasticization. Accordingly, greater or lesser wall thicknesses of the profile section can be obtained and, accordingly, different volumes and weights per unit of measurement can be changed as a function of the pull-out speed set by the operator and, as a result, considerable variations in the profile per unit of length can result.

It follows that, in order to maintain the uniformity of the profile shape, the operator must constantly monitor the thickness or weight of the section and manually adjust the speed of withdrawal with an uncertainty of approximation, thus obtaining more or less satisfactory results which depend to a large extent on experience and the speed of the corrective action.

It is known that in order to produce a smooth and uniformly cooled section, the cooling mold calibration device requires the same proportion of weight

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and volume must be preserved so that the dimensions are correct.

It is also known that the extruder and the associated device cannot always obtain a precise continuous uniform proportion of the extruded product for various reasons, for example due to a change in the dimensions of the granulate, due to lack of homogeneity of the material, due to the feed speed, due to humidity and so on, which forces the operator to carry out constant monitoring and to constantly monitor the adjustment of the withdrawal speed.

From these facts it follows that in a normal extrusion plant of the type described, as far as the automatic monitoring of the weight is concerned, which is the main reason for maintaining the shape of the profiles, no provisions are made and a very experienced operator must be appointed to carry out the monitoring and the necessary adjustments and to supervise the production plant.

The invention is based on the object of avoiding this need for continuous manual monitoring of the thickness and/or weight of the extruded sections and of carrying out this work and the resulting adjustment automatically in a more reliable manner.

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} Another purpose of the invention is

J automatically the extruded profile sections

I of the thermoplastic material, the

I meet the requirements and separate them from

I faulty profile sections that do not have the correct

I have a specific profile shape or form and consequently

I do not match in thickness dimensions and weight

According to the invention, this object is achieved by an automatic device for selecting and adjusting the profile bar sections in machines for producing extruded plastic profile sections, which is arranged downstream of an extruder device. This device has a pulling unit and a cutting device with which the continuously extruded profile is divided into sections. According to the invention, the stated object is achieved by: a base which has a

S table on which the profile section is supported

I will and slides that means are provided to

! the support table between a position in which it

aligned with the extruder unit and a lowered position in which an alignment with a scale for weighing the Profilabi cut is carried out, with the carrier firmly connected to the

] basis that means are provided to

\ a lateral discharge to opposite

; pages, depending on

the selectively determined weight of the profile sections in the lowered position, and that a

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An electronic device is provided which compares the values supplied by the scale and a setpoint generator so that the unloading of the profile bar sections takes place on one side or the other* and that the adjustment of the device producing the profile sections is carried out in accordance with the deviation.

Embodiments of the invention are described below with reference to the drawing. The drawing shows:

Fig. 1 is a side view of a device according to the invention to which a continuous rod is fed;

Fig. 2 is a view of the device corresponding to Fig. 1 in a different working position;

Fig. 3 a section along the line III-III |

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Fig. 4 is a section along the line IV-IV of Fig. 2;

Fig. 5 is a side view of a modified embodiment of the unloading station;

Fig. 6 is a side view in the direction of arrow VI-VI according to Fig. 5;

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Fig. 7 a side view in the direction of the

Arrow VIl-VII according to Fig. 5.

The drawing shows an automatic device 10 for selecting and adjusting a bar section \ i -Fuv* Macrhi non W &iacgr; ω AKcrhn &iacgr; + + a &igr;/ &eegr;&eegr; Dl ac+ &iacgr; l/mato^ia I

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downstream of an extruder _- with a drawing device shown schematically in Fig. 12, wherein a shearing device 13 divides the continuous rod into lengths of predetermined size.

The automatic device 10 comprises a base 14 relative to which a support table 15 is vertically movable, which is operatively supported by a cross table 16 via pairs of cylinders 17, 17a arranged transversely to the table, the crosspiece 16 being guided vertically relative to the side end shoulders 18 by guide columns 19 which slide in bores 20 of the same crosspiece.

The vertical displacement of the crosspiece 16 is controlled by a series of cylinders 21 or vertical displacement devices, for example pneumatic devices, connected to the same crosspiece 22 and articulated relative to the base 14 at 23.

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The two pairs of cylinders 17, 17a act as lateral unloading devices and are articulated at 24 to the crosspiece 16 and a rotating support, and the support table 15 is articulated at the end of the piston rods 25 via pivot pins 26. In addition, V-shaped support scales 27 are provided which are firmly connected to the crosspiece 16 and are designed to ^guide the ^rods 26 during the relative rotation of one of the longitudinal edges of the support table 15 during the lateral unloading, which takes _place by inclination, so that the selection of the rod sections 11 can take place.

Under the support table 15 there is a cylinder 29 which is connected to a support frame 28 which has the shape of an inverted omega, and the cylinder 29 carries at the end of its piston rod 30 a support 31 which supports two guide rollers 32 for laterally guiding the extruded plastic section, so that a mobile guide unit is formed which is generally designated by reference numeral 38 in Fig. 1 and 2.

Two holes 33 provided in the support table 15 allow the guide rollers 32 to move vertically between an upper working position and a lower position under the same table 15 while the lateral unloading takes place, there being guide studs 34 fixed to the support frame 28 via nuts 35 and in

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respective bearing bushes 27 and holes* provided in the carrier 31.

The support table 15 is also provided with three openings corresponding to the position of the divided rod 11

39, which allows the passage of weighing devices

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The weighing devices 40 are mounted on vertical columns

41 projecting from the base 14 to which they are integral, and the weighing devices 40 are supported on load cells 42 between arms 43 integral with the columns 41, and arms 44 support the same devices 44 so as to form individual weighing devices or weighing units, generally indicated at 45.

The three load cells 42 are connected via lines 46 to an electronic circuit shown at 47, which determines the final weighing value of the respective bar section 11 under test and compares the weight with a preset weight and a tolerance value and selects the bar sections accordingly.

The electronic stage 47 compares the value determined by the weighing device 45 with a predetermined value and operates via a control

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line 49 connected to a cutting machine or a cutting device 12 thereof to correct the setting so that a correct value of the bar section to be processed is delivered.

The work sequence is described below:

The continuously pxtruded thermoplastic rod runs in the direction of arrow 48.

When the rod has reached its predetermined length, it is cut off by the shearing unit 13. At this time, the support table 15, which is connected to the cross table 16, is extended by the cylinders 21 - as shown in Fig. 2 - to a fully lowered limit position. The remaining part of the extruded rod continues its travel in the direction of the arrow 48.

The cut rod section 11 is therefore I

on the table 40, the weighing device 45 to lie- jj

which are located on the load cells 42 - as shown in Fig. 2 I

visible - rest on and the tables 40 enter into f

the openings 39 which are provided in the support table 15.

are available. i

The load cells 42 generate a signal proportional to the load to which they are subjected and transmit this signal via the lines 46 to the electronic stage 47, which calculates the loads of the three

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Cells 42 are added to visually display the weight of the entire rod section 11.

If the resulting weight is within the predetermined tolerances, the support table 15 is raised at one longitudinal edge only by the pneumatic cylinders 17 operating under thrust conditions, as shown in phantom in Figure 3, while the other longitudinal edge of the support table 15 is maintained in its lowered position by the cylinders 17a operating under tension conditions, via the pivot pins 26, each pivot pin resting on its support cradle 27.

Should the weight be outside the preset tolerances, the support table 15 is correspondingly raised at its opposite longitudinal edge by the cylinders 17a operating under thrust conditions, while the other edge of the support table is held in the lowered position by the cylinders 17 operating under tension conditions.

It can thus be stated that the bar section 11 can be deposited by inclination on the side serving to collect the bars which have the predetermined tolerance values, while on the opposite side the bars which do not have the prescribed tolerances are deposited.

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It must be noted, however, that such a bar profile section 11 cannot slide either way, since it is supported by the rollers 32 carried by the guide units 38, as shown in full in Fig. 4.

Accordingly, when the support table 15 has reached its maximum inclination position, the guide rollers are caused by the pneumatic cylinders 29 to retract under the same table 15 so that the corresponding bar section can be deposited sideways downwards.

If the weight error is outside the tolerance limit, the electronic stage causes the error to be signaled acoustically and/or visually by a digital display or other display indicating the weight, and it also causes a correction and, via the control line 49, an adjustment of the speed of the withdrawal device or of the extruder 12, or of the measuring device (not shown), to the extent necessary for the weight to return to the tolerance limits.

If the weight does not return to the tolerance limits after a number of weighed bars 11 have passed through as preset by the operator, the device automatically carries out the steps required to complete the entire

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to switch off the system.

Preferably, the lateral unloading devices for the bars 11 are arranged by inclination so as to operate according to the side intended for collecting the bars which are outside the tolerance limits.

On the other hand, when profile bars are produced which are cut and sorted without having stripes on their external surfaces and have not been subjected to deformations, as is necessary, a modified lateral unloading device according to Figs. 5, 6 and 7 can be used. Laterally to the automatic device 10, the overall dimensions of which are shown in phantom, there is provided a further unloading device or lateral pushing device 50 which acts on the profile bars 12 which come to rest on the support table 15 of the extruder 12.

The lateral unloading device 50 has a group of three lateral displacement devices 54, which are arranged transversely to the support table 15 and are formed by columns 56, which lie on one side of a stationary table, which is formed by compartments 57. On the opposite side, a stirring arm 52 is provided, which protrudes like a cantilever and also engages in the device 10. A chain 63 runs in the guide 53, which is guided by motor-driven sprockets

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is driven and carries a thrust member 65, which is also slidable and acts on the individual profile bars 11 in such a way that they are transferred from the support table 15 to a table 66 which is arranged above the column 56.

Each of the three lateral displacement devices 54 is associated with a loading device 52, which carries a stack of individual tables 59, which operate as U-shaped receiving devices and receive several rods 11 inside and are designed in such a way that they lie one above the other and act as spacers, so that the profile rod sections inside are secured against possible deformations due to the weight load.

A stack of tables 59 is placed on a carriage 58 which is moved vertically by a screw 61 acting on a nut (not shown) which is fixedly connected to the same carriage 58. The screw 61 is rotatably mounted in a frame 71 and operatively connected via a gear 51 to a stepping motor 62.

At the upper portion of the frame 71, a loading element 60 is provided which acts in such a way that the last table 59 lying on top of the stack is removed by placing it in its working position on the stationary table 57 when the previous table has been withdrawn and the stepping motor has been actuated so that the stack has been raised by one step so that the height

of a single table 59,

A frame 55, which for example has the shape of a portal and is arranged laterally parallel to the bar profile sections 11 collected above the table 66, carries a gripper and a conveyor device for grasping and conveying individual tables 59.

Two crosspieces 72, which are arranged at the end of the frame 55, carry actuating elements 67, which cause a horizontal displacement for at least two gripper arm pliers 69, these pliers in turn being equipped with a drive 73 for opening - by mutual spreading - or closing - by mutual approach - of the arms 69.

In addition, a further drive 74 is provided which causes the vertical sliding movement on the guides 68 of the clamps 69 in such a way that the latter are held in the raised position or lowered position relative to the carrier and unloading table.

The individual tables 59, which are fully loaded with bar profile sections 11, are then stacked on top of each other on the flat bed 70 of a conveyor carriage 75.

The side unloading and conveying device 50 operates as follows:

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When the selection unit has determined the correct weight tolerance of a bar profile section 11, it moves the cut section 11 on the tables 66 of the columns 56 by a predetermined stroke up to a limit pitch (not shown) and shortly thereafter returns to the

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the automatic device 10 has specially recessed seats. Then the pusher element 65 conveys the cut profile sections 11 as they have been produced and brings them closer to each other, either in mutual contact or at a distance from each other by means of a stop or a limiting contact present in order to complete the predetermined quantity of bar sections. In a previous stage, the feeder element 60 has brought a table 59 onto the stationary table 57.

At this point, the gripper and conveyor device, which is formed by the horizontal drives and 73 and by the vertical drives 74, actuates the gripper arms 69.

These drive devices operate either pneumatically or hydraulically, or mechanically driven by a known drive device which is not described in detail here. When the predetermined quantity of profile sections 11 is present on the table 66, the gripping arms run

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along the guides 68 downwards and are retracted towards the middle, whereby the table 59, which is placed on the table 57, is then grasped at the bottom so that the table 59 is raised and all profile sections are conveyed upwards.

The horizontal drives 67 move sideways and transport the table 59, which is fully loaded with profile sections 11, so that it is placed on the flat bed of the carriage 75*

The arms 69 are also provided with contacts, not shown, which cause the arms to open outwards when they come into contact with the flat bed 70 or with the tables 59 already stored and located underneath.

The tables 59 can also be flat, but in the preferred embodiment, as already mentioned, they are designed in the form of a wide U-profile, with two limiting strips at the lateral ends so that the sections are held together without having to bear the weight of the following layers, thus preventing the risk of deformation.

After the wagon 75 is fully loaded, it must be transported to an unloading station or packing station and replaced by a new wagon.

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Both the loading device 52 and the lateral displacement device 54 and the tongs 69, which are provided in the form of three elements in the embodiment, can also be doubled at least with regard to the unloading device 50 in order to be operable.

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Claims (1)

Patent Attorneys ^J1 ; -j &Ggr;: ·*: _# ;D;i'pji-lng. Curt Wallach European Patent Attorneys '!'""^"^"ip l.-l ng. Gü nther Koch European Patent Attorneys Dipl.-Phys. Dr.Tino Haibach Dipl.-Ing. Rainer Feldkamp D-8000 Munich 2 · Kaufingerstraße 8 · Telephone (0 89) 2 60 80 78 · Telex 5 29 513 wakai d G 86 24 282.2 ^Date: 21 January 1987 MILANI RESINE S.p.A. Our reference: 18 356 - K/Ap Automatic device for plastic extruders Protection claims: 1. Automatic device for selecting and adjusting a profile bar section in machines for producing extruded plastic profiles, in which a pull-out device and a device for cutting the continuously drawn profile into individual sections are mounted downstream of the extruder unit, characterized in that a base (14) supports a support table (15) for the sections (11), that the support table (15) can be lowered by an adjusting device (17, 17a) from a position in which it is aligned with the extruder unit onto a weighing device for the profile bar section (11), which is firmly connected to the base, that ejectors are provided for the cut profile bars, 4 i II I ti ·<·· ; and that an electronic unit of the weighing device $ tion is assigned to the ejectors for ?;' weight-based selection. 2. Automatic device according to claim 1, &bull; characterized in that the evaluation are arranged on a crosspiece, which is arranged on the device for vertical displacement f and supports the support table. 3. Automatic device according to claim 1, characterized in that the support table has openings arranged centrally in the direction of the profile bar which is fed and tested, and that the weighing device passes through this opening in its lowered position. 4. Automatic device according to claim 1, characterized in that the weighing device comprises support tables for supporting the bar to be tested, and in that the tables rest on load cells operatively supported by the base. t * 9 · ··&diams;·■#&diams;· CC C tilt · * # i · Si Automatic device according to claim 1, characterized in that lateral guide means are firmly connected to the support table in order to guide the profile bar laterally, and in that the lateral guide means are movable between an operating position above the support table and an unloading position for unloading the bar _in which they disappear under the table. 6. Automatic device according to claim 1, characterized in that the actuating device is formed by piston-cylinder drives (17, 17a). 7. Automatic device according to claim 2, characterized in that the ejectors for the profile bars are designed as inclination devices. 8. Automatic device according to claim 7, characterized in that the inclination device is supported by piston-cylinder pairs which are arranged transversely to the support table and are anchored to the cross table or to the support table, the cylinders being acted upon in such a way that the table can be tilted to one side or the other. 9. Automatic device according to claim 1, characterized in that the electronic unit is assigned to the drive of the units of the production machine in such a way that a shutdown occurs after a predetermined weight value has passed through. 10. Automatic device according to claim 1, characterized in that the ejectors for the lateral discharge of the profile bars are formed by pusher elements which are arranged transversely relative to the support table, that internal sliding guides are provided which displace the individual profile bar sections onto a table parallel to the first table at a distance from one another. 11. Automatic device according to claim 10, characterized in that the receiving device under the parallel table is fed by a feeding device which is movable stepwise in the vertical direction and that a horizontal feeding element is provided in order to feed the receiving device on a stationary table which is connected to the transverse guide. ti · · < II«· Ul i i &bull; I - 5 12. Automatic device according to claim 10, characterized in that the receiving device is formed by tables which have the shape of a wide U and are provided with end strips. 13. Automatic device according to claim 10, characterized in that pan-like gripping devices are also provided to grasp and lift the receiving device, which is fully loaded with profile bars, in order to move it sideways and to place it on a transport trolley. 14. Automatic device according to claim 11, characterized in that the loading device has a rotatable support frame for a screw which is driven by a motor via a gear, and that a nut runs on the screw which is firmly connected to a carriage which carries the empty receiving devices stacked on top of one another. ..IM I*"'. «I.." I the nil ) t 1 1 * 1 * 15. Automatic device according to claim 13, characterized in that the gripping device comprises a frame which is mounted on cantilever-like crosspieces, "which enables a gripping of gripping arms to be operated "moderately arranged" so that they are opened and moved towards each other by an actuating element, and further actuating elements are provided to exert the horizontal movement and the transverse movement on the crosspiece.