GB2068292A - A method and an apparatus for the removal of excess layers from building elements made of cured lightweight concrete - Google Patents

Abstract

An apparatus (6) for the removal of an excess layer (4) from building elements (2) made of cured lightweight concrete comprises a front tool (9) having edges (10) which are located at a certain depth under the top surface of the excess layer (4) and a rear tool (11) having an edge (12) located at a somewhat greater depth under said surface. Hereby the excess layer is planed off from the element in two stages when the element (2) is fed through the apparatus (6), while securing a smooth and plain surface (18) on the finished element. (Fig. 3). The front tool consists of a plurality of cutting elements spread along a line, and the rear tool consists of one continuous blade. <IMAGE>

Description

SPECIFICATION A method and an apparatus for the removal of excess layers from building elements made of cured lightweight concrete When producing building elements of lightweight or aerated concrete a slurry including at least a silica-containing material, a hydraulic binding agent, a pore-forming agent and water is cast into a mould in which it is allowed to expand and stiffen to a semi-plastic self-supporting mould body. In order to delimit individual building elements helping cuts are applied into this mould body by means of cutting wires and thereafter the body is caused to finally harden by being subjected to a steamcuring operation at high pressure and high temperature.When the steamcuring is finished the various building elements included in the mould body are separated from each other in a special machine which imparts a combined rotary and displacing movement to each individual element.

Depending on the dimensions of the elements to be manufactured more or less thick excess layers are obtained on the outermost elements of said mould body. It these excess layers are more than 55 mm in thickness they can be removed by means of the abovementioned separating machine. If, however, the thickness is less than 55 mm a manual chipping-off of the excess layers is needed.

This work is not only time-consuming and costly but furthermore it often results in damages because the layers may be imtimitely adhered to the underlying buiding elements and thereby carry away surface portions thereof. If the surface of the elements is destroyed in this manner, the elements either have to be rejected or repaired.

The present invention aims at eliminating the manual chipping-off of the excess layer and securing the achievement of smooth, undamaged surfaces of the underlying building element. According to the invention this is achieved by providing a relative movement between the building element in question and a processing apparatus which comprises two spaced apart tools, namely a front tool having at least one processing edge which is located at a certain depth below the top surface of the excess layer and a rear tool having at least one processing edge which is located at a greater depth below said surface than the front tool edge so as to remove two part layers from the element during said relative movement, namely a first part layer the thickness of which is determined by the depth of the front tool edge below said layer surface and a second part layer the thickness of which is determined by the difference in depth between said front tool edge and said rear tool edge. By choosing the thickness of said second part layer rather small, e.g. in the region of 5-1 5 mm and under all circumstances smaller than 25 mm, no great forces are needed for breaking loose the excess material from the element and thereby the risk for carrying away portions of the uncovered surface of the element becomes negligible.

The features of the above-mentioned processing apparatus as such appear in detail from the attached claims.

With reference to the accompanying drawing a detailed description of an embodiment of the invention put forward as an example will follow below. In the drawing Fig. 1 is a perspective view illustrating a mould body of steamcured lightweight concrete during the passage thereof through the processing apparatus according to the invention, Fig. 2 is a cross section through an enlarged portion of the same mould body and Fig. 3 is a sectional view of the mould body and the processing apparatus shown in Fig. 1.

The mould body which in its entirety is designated 1 in the drawing comprises a plurality of building elements 2 which are delimited from each other by means of horizontal helping cuts 3 which have been applied into the body before the streamcuring thereof.

These cuts have a delimiting effect, but do not prevent the individual elements from being rather strongly adhered to each other and therefore they have to be separated from each other mechanically as previously pointed out.

The topmost element 2 of the body presents an excess layer 4 which shall be removed. To this end the mould body is fed in the direction of the arrow 5 through a processing apparatus of the invention generally designated 6.

The above-mentioned apparatus includes a transport or feeding track for the mould body 1, said track being schematically shown at 7.

Across the track 7 a frame 8 extends which support two spaced-apart cutting or planer-like tools, namely a front tool 9 having at least one preceding edge 10 located on a certain level above the track or path 7 and a rear tool 11 having at least one processing edge 1 2 located on a somewhat lower level over the track and said front tool edge 1 0. In the exemplified embodiment the first-mentioned tool 9 is composed of a plurality of individual teeth or shanks 1 3 which are spaced apart from each other and each of which has an edge 10. The rear tool 11 on the contrary consists of one single oblong continuous blade.This blade is adjustably mounted on the frame, more precisely by being pivotable about articulations 14, the pivoting movement thereof being provided by two piston-cylindermechanisms 15, suitably of the hydraulic type. Hereby the blade edge 1 2 can be accurately adjusted into the same plane as the cut 3 between the element 2 and the excess layer 4.

As appears from Fig. 3 the blade 11 as well as the shanks 1 3 are obliquely arranged rela tive to the horizontal plane in which the layer 4 and the element 2 are located in this case.

More precisely the blade and the shanks are inclined approximately 45" relative to the horizontal plane, though larger angles may be involved too.

In Fig. 2, 1 6 designates the plane in which the edges 10 of the front tool 9 are intended to attack the material of the excess layer 4.

1 7 designates the top surface of the layer 4.

The apparatus described operates in the following manner. When the mould body passes the two tools 9, 11 two part layers are removed from the excess layer, namely a first part layer the thickness t1 of which is determined by the depth of the front tool edges 10 below the top surface 1 7 of the layer 4 and a second part layer the thickness t2 of which is determined by the difference in depth or level between the front tool edges 10 and the rear tool edge 1 2. The removal of said part layers takes place by crushing and/or shearing the material. In order to obtain an intact smooth top surface 1 8 of the finished element 2 the thickness t2 of the second part layer should be less than 25 mm as previously mentioned.

Thus experimental tests have shown that if this layer thickness t2 exceeds said figure there will be a risk that material from the element 2 itself is taken away together with the second part layer due to the adhesivity which occurs in the interface constituted by the cut 3.

After having passed the apparatus 6 shown in the drawing the element 2 which has been relieved of the excess layer 4 may be fed through a scraping device (not shown) and thereafter possibly through a clean-sucking device. The element thus cleaned may possibly also be fed through a device for applying onto the surface 1 8 a suitably hydrophobation agent, such as silanes or polysiloxanes.

Though a mould body 1 comprising a plurality of building elements 2 is shown in the drawing usually only one single element 2 together with its excess layer 4 is fed through the processing apparatus 6 after the elements themselves have been previously separated from each other in the manner indicated above. In order to make the processing of elements having varying thicknesses possible not only the rear tool 11 but also the front tool 9 may be vertically adjustable so that the attack line 1 6 of the tool will be located on the appropriate level above the cut 3. It may further be pointed out that the apparatus described is fit for use irrespective of the question whether any helping cuts 3 occurs in the element or not. Thus, also in the case when such cuts are missing the rear tool 11 will plane off the second part layer while obtaining a smooth top surface 1 8-provided that the difference in level between the edges 10 and 1 2 is not too great. Instead of just two tools of the type described three or even more tools may be included in the apparatus 6, said tools being located on different levels after each other along the feeding path 7. It should also be pointed out that the tools do not at all have the extend horizontally, but they may be oriented in any arbitrary angle relative to said plane. They may for instance be vertically arranged. Also other modifications of the invention are possible within the scope of the accompanying claims.

Claims (10)

1. A method for the removal of excess layers from building elements of cured lightweight concrete, characterized in that a relative movement is provided between said element and a processing apparatus which comprises two spaced apart tools, namely a front tool having at least one processing edge which is located at a certain depth below the surface of the excess layer and a rear tool having at least one processing edge which is located at a greater depth below said surface than the front tool edge so as to remove two parts layers from the element during said relative movement, namely a first part layer the thickness of which is determined by the depth of the front tool edge below said layer surface and a second part layer the thickness of which is determined by the difference in depth between said front edge and said rear tool edge.

2. A method according to claim 1, characterized in that a helping cut is made in the element before the curing in a manner known per se, said cut delimiting the excess layer from the element itself, the edge of the rear tool being located in the same plane as said cut.

3. An apparatus for the removal of excess layers from building elements of cured lightweight concrete, characterized in that it comprises two spaced-apart tools, namely a front tool having at least one processing edge intended to be located at a certain depth below the surface of the excess layer and a rear tool having at least one processing edge intended to be located at a greater depth under said surface than the front tool edge so as to remove two part layers from the element when a relative movement is provided between said element and said tools, more precisely a first part layer the thickness of which is determined by the depth of the front tool edge below the layer surface and a second part layer the thickness of which is determined by the difference in depth between the front tool edge and the rear tool edge.

4. Apparatus according to claim 3, characterized in that the difference in depth between the front tool edge and the rear tool edge is less than 25 mm.

5. Apparatus according to claim 3 or 4, characterized in that the front tool comprises a plurality of individual shanks which are spaced apart along a line being perpendicular to the direction of said relative movement.

6. Apparatus according to anyone of claims 3-5 characterized in that the rear tool consists of one single continuous blade.

7. Apparatus according to claim 5 or 6, characterized in that the tool blade and/or shanks are inclined at least 45' relative to the plane of the excess layer or the element.

8. Apparatus according to anyone of claims 3-7, characterized in that at least the rear tool is adjustably mounted on a frame, e.g. by means of piston-cylinder mechanisms in order to make possible an adjustment of the edge of the tool into the same plane as a helping cut made in the element before the curing thereof.

9. A method substantially as hereinbefore described.

10. Apparatus substantially as hereinbefore described and as shown in the figures of the accompanying drawing.