Patent Application
20090091055
1. Field of the Invention
The invention relates to a method of producing pipes having a transverse profile from thermoplastic material by means of circulating mold segment halves which are arranged in two opposite rows downstream of an extrusion head and combine in pairs to form a closed hollow mold along a linear molding path,
wherein each of the unconnected mold segment halves of a row are guided out of the molding path at a downstream end in a direction substantially at right angles to a direction of production by means of a conveying device and are guided back to the upstream end of the molding path where they are re-fed into the molding path, and
wherein downstream of the downstream end of the molding path and on both sides thereof, a respective additional mold segment half is stored in a parking position, the additional mold segment half being feedable into the molding path by means of the conveying device.
Furthermore, the invention relates to an apparatus for producing pipes having a transverse profile.
2. Background Art
A method and an apparatus of this type are for example known from U.S. Pat. No. 5,693,347. By means of the conveying device, the respective mold segment halves used in the production of the corrugated pipe are removed from the molding path at the downstream end thereof and returned to the beginning of the molding path at the upstream end of the apparatus where they are fed back into the molding path. Each time a pipe form, in particular a socket, is to be produced which differs from the regular cross-section of a corrugated pipe, a pair of additional mold segment halves is additionally fed into the molding path from a parking position downstream of the molding path by means of the conveying device. After passing through the molding path, these additional mold segment halves are removed from the molding path by the conveying device and returned to the parking positions. Afterwards, the conveying device moves back to the downstream end of the molding path where it removes the next pair of mold segment halves in order to return them to the beginning of the molding path where they are fed into the molding path. The result of this embodiment was that the production speed of these apparatuses is limited.
Thus it is the object of the invention to develop a method of the generic type such that the production speed can be increased, and to provide an apparatus for realization of the method.
In a method of the generic type, this object is attained in that the additional mold segment halves are removed from the molding path at the down-stream end by means of a auxiliary conveying device, which is separate from the conveying device acting as main conveying device, before being moved to the parking positions while a pair of mold segment halves, which is disposed directly upstream of the additional mold segment halves in the molding path when seen in the direction of production, is returned to the upstream end of the molding path where it is fed into the molding path.
Due to the fact that the removal of the additional mold segment halves from the molding path and their transport to their parking position is dispensed with, the entire production process, more specifically the extrusion rate and the speed of the mold segments on the molding path, can be increased considerably since the mold segment halves are moved opposite to the direction of production on a substantially straight line so that conveyance can take place at a very high speed.
In an apparatus of the generic type, this object is attained in that down-stream of the molding path, an auxiliary conveying device is provided for removing the additional mold segment halves from the molding path at the downstream end thereof and for moving these additional mold segment halves to their parking positions. The main conveying device and the auxiliary conveying device may be formed like a gantry crane.
Further features, advantages and details of the invention will become apparent from the description of an embodiment by means of the drawing.
A counterpart bearing 14 is provided above the base 1 and above the mold. It has a base plate 15 on which is supported an upper driving pinion 16. This upper driving pinion 16 is likewise non-rotatably mounted on a drive shaft 17, both ends of which are run in bearings 18, 19 which are fastened to the base plate 15. The drive shaft 17 is driven by a gear motor 20 which is attached to the adjacent bearing 19. Supporting rollers 21 are located on the lower side of the base plate 15, having a horizontal axis of rotation 22 and supporting themselves on supporting surfaces 23 formed on the upper side of each mold segment half 4, 5, which defines the position of the counterpart bearing 14 relative to the mold segment halves 4, 5. Guide rollers 24 are positioned on the lower side of the base plate 15, having a vertical axis of rotation 25 and engaging laterally with guide surfaces 26 that are also formed on the upper side of the mold segment halves 4, 5. By means of these guide rollers 24, two mold segment halves 4, 5 that constitute a mold segment 3 are guided and held together by their upper portion. Between the supporting surfaces 23 and the guide surfaces 26, respectively, the upper driving pinion 16 engages with an indentation 27, which is formed on the upper sides of the mold segment halves 4, 5. Only one third to one quarter of the amount of advance exercised on the mold segments 3 by the lower driving pinion 8 is transmitted to the mold segments 3 by the upper driving pinion 16. The counterpart bearing 14 is supported in torque converter bearings 28, which are mounted on the base 1 and stand vertically upright thereon and which absorb the torque exercised by the gear motor 20 on the counterpart bearing 14.
A main conveying device 29 for the mold segment halves 4, 5 is provided above the base plate 1. This main conveying device 29 is designed in the way of a gantry crane. It has two guide rails 31, 32 extending parallel to each other and parallel to the direction of conveyance 6, to the central longitudinal axis 30 of the mold segments 3 and to the base 1. These guide rails 31, 32 are disposed above the counterpart bearing 14 and supported relative to the base 1 by props 33. A conveying bridge 34 is supported on the guide rails 31, 32 by bogie wagons 35. Displacement of the conveying bridge 34 on the guide rails 31, 32 takes place by means of linear drives 36, which are spindle drives in the concrete embodiment. Consequently, these linear drives 36 have threaded spindles 37, which are disposed on the guide rails 31, 32 and on which are disposed threaded nuts 38 which are again fixed to the bogie wagons 35. The threaded spindles 37 are driven each by a gear motor 39, 40, these two gear motors 39, 40 being forcibly synchronized by way of a horizontal coupling shaft 41 that extends at right angles to the guide rails 31, 32. These two threaded spindles 37 are driven precisely at the same speed so that the conveying bridge 34 is displaced free from tilting on the guide rails 31, 32. The conveying bridge 34 has two bridge sections 42, 43, which, seen from the guide rails 31, 32, run toward each other, inclining toward the base 1. Consequently, the lowest distance of the bridge 34 from the base 1 is in the middle of the bridge 34 vertically above the central longitudinal axis 30. A conveying carriage 44, 45 is displaceably disposed on each of the two bridge sections 42, 43 and is movable in the respective direction of displacement 46 or 47 by means of a linear drive 48 or 49. These linear drives 48, 49 substantially consist of a threaded spindle 50 that is housed in the respective bridge section 42 or 43 and engages with a threaded nut 51 on the respective conveying carriage 44 or 45. The two threaded spindles 50 are driven by a common gear motor 52. The gear motors 39, 40 and the gear motor 52 are reversible motors, i.e. they are suitable for forward and reverse motion.
A conveying arm 53, which extends vertically downwards, is attached to each conveying carriage 44, 45. Each conveying arm 53 is provided with a holding device 54 for a mold segment half 4 and 5, respectively. Allocated to the holding device 54, a holding abutment 55 is formed on each mold segment half 4 and 5, respectively. Each holding device 54 has an upper stop 56 which a holding abutment 55 is pressed against from below. Further, a clamping device 57, which substantially consists of a pneumatic or hydraulic piston-cylinder drive 58, belongs to the holding device 54. A locking pin 60 is formed on the piston rod 59 of this drive 58, which, upon corresponding actuation of the drive 58, engages with a locking recess 61 on the lower side of the holding abutment 55, simultaneously pressing the abutment 55 against the stop 56. In the position shown on the left of
Proximity switches—only some proximity switches 62, 63, 64, 65 of which are shown—are disposed on the guide rails 31, 32 and, upon approach of the conveying bridge 34, transmit signals reflecting the position thereof to a central control unit (not shown). Proximity switches 66, 67 are also provided on the conveying bridge 34, transmitting signals to the central control unit that reflect an inner or outer position of the respective conveying carriage 44, 45.
Apart from the main conveying device 29, an auxiliary conveying device 29′ is provided which is designed like the main conveying device 29 with the difference that the guide rails 31′, 32′ thereof, which are arranged between the guide rails 31, 32, only extend from the downstream end 68 of the molding path to the end 69 of the apparatus which is disposed even further down the line when seen in the direction of production 6. Since the design otherwise corresponds to that of the main conveying device 29, all equal or similar parts are denoted by reference numerals which are identical to those of the main conveying device 29 but are marked with an apostrophe. Therefore, reference can be made to the entire preceding description. Also shown in
Two tubes of thermally plastic material are extruded from the extrusion head 7 of the extruder, entering the mold at the upstream end 70 of the molding path 2 where they are molded, by means of overpressure or vacuum and, if necessary, support air, into a compound pipe 71 which has a smooth inside wall and an outer corrugation 72, as known in detail from EP 0 563 575 A1 (corresponding to U.S. Pat. No. 5,320,797) which reference is made to. By alternative, it is also possible to mold single-piece corrugated pipes or ribbed pipes.
If a profile differing from the corrugation 72, for instance a socket 73, is to be produced on the pipe 71 at in each case longer intervals, a pair of special mold segment halves, for instance a pair of socket mold segment halves 74, 75, needs to be fed into the molding path 2. These mold segment halves 74, 75 are stored in parking positions 76, 77 which are formed by pedestals 78, 79 on which these mold segment halves 74, 75 are placed when they are not involved in the pipe molding process. These parking positions 76, 77 are adjacent to the end 69 of the apparatus. The auxiliary conveying device 29′ serves to return these mold segment halves 74, 75 from the downstream end 68 of the molding path 2 to their parking positions 76, 77.
The mold consisting of the mold segments 3 advances in the direction of production 6. The pipe 71 produced therein migrates at the same rate. When a mold segment 3 has reached the downstream end 68 of the molding path 2, the two mold segment halves 4, 5 that constitute this mold segment 3 must be removed from the molding path 2 crosswise of the direction of production 6. As shown in
When the upstream proximity switches 62 are reached, the gear motors 39, 40 are stopped so that the conveying bridge 34 is at a standstill. The gear motor 52 is switched on, moving the conveying carriages 44, 45 inwards toward the molding path and leads, at the upstream end, the two mold segment halves 4, 5 crosswise of the direction of production 6 into the molding path 2, as shown by dashed lines in
If it is desired to form a socket 73 in the continuous pipe 71, the main conveying device 29 is moved into the position shown by a dash-dot line according to
As shown by
While the last pair of mold segment halves 4, 5, which—according to FIGS. 6 and 7—had been disposed upstream of the socket mold segment halves 74, 75 in the direction of production 6, is still being returned to the upstream end 70 of the molding path 2, the auxiliary conveying device 29′ is set in motion so as to move to the downstream end 68 where it is stopped by respective signals of the proximity switches 62′. The conveying carriages 44′, 45′ are moved inwards towards each other until they are stopped by way of proximity switches 67′, and the conveying arms 53′ and the socket mold segment halves 74, 75 are interlocked. The conveying carriages 44′, 45′ are then moved outwards until they are stopped by the proximity switches 66′. Afterwards, the auxiliary conveying device 29′ is returned to the parking positions 76, 77 in the direction of production 6 where the socket mold segment halves 74, 75 are placed on the pedestals 78, 79. The auxiliary conveying device 29′ is stopped at the parking positions 76, 77 by way of proximity switches 65′. The entire process takes place simultaneously with the return of the last mold segment halves 4, 5, which move upstream of the socket mold segment halves 74, 75, to the upstream end 70 and the feeding into the molding path 2. Thus, no additional time is required for removing and conveying the socket mold segment halves 74, 75 away from the molding path 2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 047 662.2 | Oct 2007 | DE | national |
