EP0056020B1

EP0056020B1 - A method and apparatus for manufacturing profiled elements

Info

Publication number: EP0056020B1
Application number: EP80900687A
Authority: EP
Inventors: Per-Eric Bondpers; Per Inge Ingesson
Original assignee: A-BETONG AB/SABEMA MATERIAL AB; Sabema Material AB; Abetong AB
Current assignee: A-BETONG AB/SABEMA MATERIAL AB; Sabema Material AB; Abetong AB
Priority date: 1980-04-09
Filing date: 1980-04-09
Publication date: 1984-08-15
Also published as: EP0056020A1; WO1981002865A1; DK538881A; DE3068934D1; ATE8972T1

Abstract

In a method of manufacturing profiled elements from a hardenable mass such as concrete, using a casting machine (1), the mass is discharged from said machine in the form of a continuous casting via an exchangeable nozzle (1a), which determines the profile shape of the casting, whereafter the casting is cut into elements (8) of desired lengths To enable rational handling of the profiled casting and automatization of the production sequences without stocking in relation to hardening of the elements, the profiled casting is discharged onto a transport unit (10) provided with an endless movable belt (12) and cut. The belt (12) is caused to stop and the actual transport unit moved further in a circuit path (A-K) during which the element is hardened, and after hardening discharged from the transport unit, whereafter the empty transport unit is returned to the starting position for receiving a further profiled casting from the casting machine (1) When the casting is fed onto the transport unit and the hardened element (8) discharged there from, the belt (12) is driven by means of an external drive source (21) which, to this end, is connected to one of the belt-turn shafts (21a) of the endless belt. The belt can also be driven when the transport unit passes a cleaning station (1) during its return to the delivery station (A) after curing of the casting. To enable the available space to be used in a more rational manner when hardening the castings, preferably a plurality of transport units, for example four such units, are stacked one over the other in a frame prior to said hardening process, and transferred, thus stacked, to a hardening storage site (E), said transport units being de-stacked subsequent to said hardening process, whereafter the finished profiled elements (8) are discharged The invention also relates to apparatus for manufacturing profiled elements by means of the method according to the invention.

Description

The present invention relates to a method and apparatus for manufacturing profiled elements from a hardenable mass, such as concrete, while using a casting machine from which the mass is discharged in the form of a continuous casting or string via a nozzle which is preferably exchangeable and which determines the profiled shape of the casting. More specifically the invention relates to a method and apparatus defined in the preamble of claim 1 and 2, respectively.
In a previously known method of manufacture there is used a casting machine provided with screw feed means, in which machine the concrete mass is compressed upstream of the nozzle, whereat no other pressure than that provided by the screw is exerted onto the concrete mass for its correct feed through the nozzle. In relation to conventional concrete casting methods, there is provided, i.a., the advantage that the cast concrete mass need not be subjected to any particular vibrations.
Another advantage afforded by said known method is that if so desired or so required, the concrete casting or string can be readily provided with a reinforcement. To this end, reinforcing rods of suitable length can be introduced through an opening which is located on the other side of the machine in register with the nozzle, whereat the rod or rods is or are inserted to an extent such that they pass out through the nozzle together with the casting exiting therethrough. When the nozzle has discharged a casting of sufficient length, normally about 1/2 m, the friction between the reinforcing rods and the casting is sufficiently great for the casting to entrain therewith the rod or rods during continued discharge of the casting. The length of the reinforcing rod or rods is previously adapted to the predetermined length of the profiled element in question, the casting being cut when the full length of one or more reinforcing rods has passed through the nozzle.
Owing to the fact that the profiled casting is discharged in the manner aforementioned, on said transport unit provided with an endless, movable belt, a high degree of reliability is obtained in conjunction with the outfeed of said casting, since the speed at which the belt moves can be synchronized exactly with the speed at which the profiled casting is discharged from the casting machine. Consequently, the risk of damaging the profiled casting when being discharged through the nozzle can be substantially fully eliminated.
In other known methods, the concrete continuous casting is discharged onto a smooth surface or a conveyor belt whose movement is controlled or driven by the discharged casting. The continued handling of the casting is effected substantially manually, which has created a number of complications and involved high costs. Even in those cases known hitherto where the casting is fed out onto a movable conveyor belt driven by a separate motor, great difficulties have been encountered during the continued transport and handling of the casting, primarily with respect to the handling of the casting during its transport to a curing or hardening storage site. As a rule hardening of the casting requires a period of from 3 to 5 hours or more, and it will readily be understood that the hardening operation must, of necessity, take place at a site in the factory area where those elements undergoing a hardening process do not prevent the discharge of further profiled castings from the casting machine.
Examples of known methods of the aforedescribed kind and other kinds are disclosed in SE-C-87 517 and 99475 and SE-A-302 738 and 399 202.
FR-A-1 247 052 discloses a method which comprises discharging the profiled elements onto a transport unit provided with an endless movable belt, the belt being caused to stop after having received the profiled element and the transport unit is moved in a circuit path during which the element is hardened and subsequently removed from the transport unit; thereafter the empty transport unit is returned to the starting point in order to receive a new profiled element.
In this known method the casting machine is not an extruder producing a continuous string via a nozzle, which subsequently is cut transversely into the desired lengths, but a mould equipment which produces the elements in the desired lengths.
An object of the present invention is to provide a method and apparatus of the aforedescribed kind in which the production sequences can be carried out in a highly reliable and accurate fashion during positive and careful handling of the discharged continuous casting so as to enable the manufacturing operation to be automatized with a minimum of manual operations in said sequence.
Another object of the invention is to provide a method and an apparatus of the aforementioned kind which enable the manufacture of profiled elements of any cross-sectional or profile shape to be rationalized, the maximum size of the manufactured element being determined by the dimensions of the nozzles which can be mounted onto an existing casting machine.
A further object of the invention is to provide a method and an apparatus which enable the manufacture of profiled elements from differing types of hardenable masses, i.e. not only concrete, and in which a discharged continuous casting can be cut into any number of separate elements and thus also of any desired length, in which case a complete group of such elements is subjected to simultaneous and similar handling operations during transport to a hardening storage site, and subsequent to being hardened, to a receiving station.
The method according to the invention is mainly characterized by claim 1.
Because the whole unit as such, carrying a profiled casting, is transported, purposeful and positive handling of the profiled casting is permitted, both to a hardening storage site and, subsequent to completion of the hardening process, optionally to a station in which the casting is finally worked, and then removed from the transport unit. A particular advantage in connection herewith is that when the casting is transported to the hardening storage site, the vertical space in the factory area can be utilized in that, for example by using a separate stand, frame or the like, several conveyor units can be handled simultaneously, stacked vertically one above the other.
A further advantage is that simple and purposeful conveying means for the transport units is provided, e.g. in the form of a roller path which permits such accurately guided and simply controlled horizontal transport of the units that the apparatus can be readily automatized with the use of limit switches and like standard devices which provide for accurate guidance and control of the working sequences.
In addition, in the method according to the invention the profiled casting is discharged onto the transport unit and readily cut into a plurality of separate elements, if so desired. In this way, the method according to the invention enables many differing types of profiled elements comprising hardenable masses of varying kinds and for different purposes to be readily manufactured. Examples of elements which can be manufactured by means of the method according to the invention include differing kinds of profiled concrete elements, such as beams, battens, curbing stones, stays and struts of differing kinds, floor elements, such as so-called split floors for cow sheds and the like, roofing tiles, hollow blocks etc. Examples of other kinds of elements which can be manufactured with other hardenable masses include roofing stone, roofing tiles, profiled elements, beams and posts of plastics material etc.
In practice, the belt on the transport unit is driven by the external source at least whilst the concrete casting is fed onto and/or the hardened element is removed from the transport unit. The advantages obtained when driving the transport unit at these two stations will be obvious in the light of the aforegoing. The most important advantage is that manual handling of the casting can be avoided when the casting is delivered from the casting machine and when the finished element is removed from the transport unit.
By using an external drive source for driving the belt, the same drive source can be used for all transport units, thereby rendering the construction considerably more simple and less expensive. An external drive source at the receiving station in connection with the casting machine can also, to advantage, be provided with a variator which enables the speed of the conveyor belt to be accurately adjusted to the outfeed speed of the casting. Further, the correct length of the casting can be readily adjusted with the aid of a pulse counter arranged to automatically stop the outfeed of a casting when the correct length has been reached.
The pulse counter may also be arranged to provide a given additional length, to enable the casting to be centered on the transport unit, thereby facilitating the further handling of the casting.
Prior to energizing the outer drive source, the transport unit is locked in position, this being carried out automatically as the drive source is energized.
In practice, four transport units, for example, can be stacked one above the other in a frame or rack arranged to be lifted by means of the hook of a traverse crane or the like.
The empty transport units are returned, preferably via a cleaning station, in which the belts of the units are driven. This renders the cleaning operation more effective.
The invention also relates to apparatus for carrying out the aforedescribed method, the main characterizing features of the apparatus being disclosed in claim 2.
An exemplifying embodiment of the invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 is a plan view of an apparatus for carrying out the method according to the invention.
Figure 2 is a perspective view of a transport unit for use in the apparatus shown in Figure 1.
Figure 3 is a perspective view of a transport frame supporting a plurality of transport units according to Figure 2, said frame being arranged to transfer transport units carrying profiled castings or elements to and from a hardening storage site.

The plan view shown in Figure 1 illustrates schematically principal parts of an apparatus for manufacturing continuously cast profiled elements of concrete while using a casting machine 1 having an exchangeable nozzle 1a. The machine is provided with a feed screw (not shown), which, via the nozzle 1 a, delivers a profiled casting onto a transport unit 10, which will be hereinafter described.
The concrete mass is charged to the machine 1 via a container 2 and a cross feeder 3.
The casting discharged from the machine 1 is reinforced with reinforcing rods 4 from a reinforcing rod store 5. The rods 4 are placed on a carriage 6 and are introduced centrally into the machine, where they are fed out, whilst guided by a separate calibrating head, together with the concrete casting discharged through the nozzle. The carriage is caused to move synchronously with the concrete casting, the reinforcing rods being inserted until they are gripped by the casting.
The profiled casting is discharged onto a transport unit 10 at a station referenced A in Figure 1. As the casting is fed onto the transport unit, the conveyor belt 12 of said unit is driven by an external drive source, said source having the form of a drive motor 21 provided with a variator 22. The drive unit has an output shaft 21a, which is connected, via a claw coupling 23, to a belt-turn shaft 14 cooperating with the belt 12 of the transport unit. The belt-turn shaft at the opposite end of the transport unit is referenced 13.
Before the output shaft 21 a of the drive motor is connected to the shaft 14, the transport unit is locked in position by means of a fixing claw 20' arranged to cooperate with a transversely extending rod 20 at one end of the transport unit. The claw 20' is shown schematically in Figure 2.
Locking of the transport unit 10 and its connection to the drive motor 21 are effected fully automatically.
The correct length of the elements is determined by means of a pulse counter (not shown) which automatically interrupts the outfeed from the casting machine 1 when the correct element length has been reached. The pulse counter can, at the same time, be arranged to provide certain additional lengths, to enable the continuous casting to be centered on the belt.
When an element of the correct length has been obtained, the casting is cut, which can either be effected manually or by an automatically operating cutting means (not shown). The transport unit is then moved around, in a circle, while passing certain treatment stations and other stations referenced B to K in Figure 1. The casting and the transport unit respectively are subjected to certain handling and/or treatment processes at the different stations.
Fine polishing of the cut concrete surfaces is carried out at station B. Station C can be employed to check the result of those working operations carried out hitherto, it always being ensured that the production sequence is interrupted for those profiled castings which cannot lead to an acceptable final product.
At station D, a plurality, suitably four, of transport units are automatically stacked one above the other, to which end there is used a separate stacking rack 41 having vertically movable arms.
After stacking said four transport units in the stacking rack 41, a transport frame 40 of the kind shown in Figure 3 is moved to the rack 41. The transport frame 40 is moved on rails 42 in the floor, which includes a turn-plate 42a permitting the transport frame to be turned through 90°. The purpose of this is to transfer the transport units to the station E, which comprises a hardening storage site.
The transport frame 40 shown in Figure 3 comprises a vertical frame structure 40a having a lower frame part 40b which carries wheels 40c. Four pairs of raiseable and lowerable arms 40d for carrying the transport units 10 are activated by two hydraulic devices 40e. The transport units 10 are thus transferred from the stacking rack 41 to the transport frame 40, by moving the transport frame close into the rack 41, whereupon all of said arms 40d are lifted into engagement with the transport units 10.
Subsequent to turning the transport frame 40 through 90° by means of the turn-plate 42a, the transport units are removed in a corresponding way at the hardening site 43 at station E, which as beforementioned comprises a hardening storage site.
The hardening station 43 may have the form of a slowly moving conveyor, on which the units move from one end of the conveyor to the other over a period of time required to harden the castings. Alternatively the station may have a form of a stationary frame structure in which transport units are stacked one above the other until the frame is completely or partially filled, said units remaining in rest until the castings have hardened.
Irrespective of the form taken by the hardening station E, corresponding transport of units from the other end of the hardening station to the de-stacking station F takes place by means of a similar transport frame 40' which is movable on rails 42' having an associated turn-plate or table 42'.
At the de-stacking station F, the sequence of operations is the opposite to that at the stacking station D. When a transport unit 10 has taken a position in register with an adjacent receiving table at the discharge station G the conveyor belt 12 is started with the aid of an external drive motor 21 located at said station, the concrete profiled element being transferred to station G, at which any final adjustment required to the element is made before the finished element is finally discharged.
At the same time, the return transport of the empty transport unit 10 is commenced, said unit first passing a cleaning station H, in which the transport unit is fixed and connected to an external drive motor 21 for driving the belt of said unit, thereby facilitating cleansing of the transport unit by means of, for example, a water sprayed brush.
The transport unit then passes a further two stations, designated I and J, which can be used as buffer stations before the transport unit finally reaches the station K, where a cross conveyor 50 automatically transfers the transport unit to the starting position at station A, where a new cycle is commenced. The transport units are conveyed between stations D-E-F on a roller path 30, 30a of the kind shown in Figure 2. This permits accurate guidance and control of the transport sequence. The same is true of the transportation of the continuous casting and profiled element provided when the belt 12 is started with the aid of the external drive source 21.
Depending upon the type of element being manufactured, the transport cycle may contain additional stations. Thus, there can be provided a cutting station in which, primarily, those elements which exhibit manufacturing faults, for example because the reinforcing rods project out of the element, or like faults, can be processed. Further, elements which have certain defects can be at least partially "saved", by cutting away the defected parts of said elements while recovering the remaining part thereof.
Those skilled in the art will understand that the described production sequences can be modified in different ways, depending upon the type of element to be manufactured by means of the method according to the invention. When using masses which are cured relatively quickly, the stacking and de-stacking stations D and F, and the hardening storage site E can be omitted, the manufacture of the elements instead taking place in a substantially uniform stream, in which hardening of the elements takes place during the time the transport units are still on the underlying roller conveyor.
Instead of the roller conveyors 30, 30a other types of transport means for said units are conceivable. A requirement for a highly-automatized industrial manufacture of profiled elements, in which is expressed the actual meaning, is that the manufacturing sequences must be accurately guided and controlled.

Claims

1. A method of manufacturing profiled elements from a hardenable mass, such as concrete, using a casting machine (1) from which the mass is delivered in the form of a continuous casting or string via a preferably exchangeable nozzle (1a) which determines the profile shape of the casting, including the steps of

discharging said profiled casting onto a transport unit (10) provided with an endless movable belt (12), and cutting it to elements of desired length; characterized by

causing the belt to step after receipt of the element and moving the actual transport unit (10) in a circuit path during which the element (8) is hardened and, subsequent to said hardening process, removing said element (8) from the transport unit (10);

returning the empty transport unit (10) to the starting position for receipt of a new profiled casting from the casting machine; and

driving the belt (12) of the transport unit (10) at least while the casting is being fed onto and/or the hardened element is removed from the transport unit (10);

driving said belt (12) by means of an external drive source (21) having an output shaft (21a) which is temporarily connected to a belt-turn shaft (14) arranged at one end of the transport unit (10);

stacking two or more transport units (10) prior to said hardening process, one above the other, in a frame (41) and transferring the units, thus stacked, to a hardening storage site (E); and

subsequent to said hardening process, de-stacking said transport units (10) and removing the finished profiled elements (8).

2. An apparatus for manufacturing profiled elements from a hardenable mass such as concrete, comprising

a casting machine (1) provided with a preferably exchangeable nozzle (1 a) for delivering a profiled casting of the hardenable mass;

a transport system having a plurality of stations (A-G) for handling, working and/or hardening cut pieces of the casting; said transport system comprising

a plurality of transport units (10) having endless movable belts (12); characterized in that said transport system further comprises

means (30, 30a) for transporting said transport units (10) in a circuit path during passage of said stations (A-G);

means (20) for temporarily holding the transport units (10) stationary in at least one station, such as a casting-delivery station (A) and/or a casting discharge (G);

external drive means (21, 23) for driving the conveyor belt (12) of the transport unit (10) in at least one such station (A-G), said external drive means comprising an external drive motor (21) having an output shaft (21 a) arranged to be connected with one of the belt-turn shafts (14) of the conveyor belt (12); and in that

the transport means of the transport units comprise at least one roller path (30, 30a) for horizontal transport of consecutive transport units (10) to a stacking station (D) and at least one transport rack (40) for transferring two or more transport units (10) stacked one above the other to and from a hardening storage site (E).

3. Apparatus according to claim 2, characterized in that a drive motor (21) for driving the conveyor belt (12) of said units is arranged at a casting delivery station (A), a de-stacking or discharge station (G) and a cleaning station (H) for empty transport units.