Abstract
A method for casting a hollow core concrete product with a substantially horizontal slipform casting process, where concrete mass is fed at least in one feeding stage through a limited cross-section (5, 6, 7) moving progressively along with the cast, and at least one core is formed in the concrete product to be cast with a core forming member (4), wherein the thickness of webs between the cores of the product to be cast are changed during the slipform casting process by changing the width of the at least one core forming member (4). The invention also relates to such an apparatus and a core forming member.
Claims
1. An apparatus for casting a hollow core concrete product with a substantially horizontal slipform casting process, the apparatus comprising a slipform mold defining a limited cross-section for the product to be cast, means for feeding concrete mix through the slipform mold at least in one feeding stage, and at least one core forming member, and means for changing the width of the at least one core forming member during the slipform casting process; the apparatus further comprising a control system for measuring a casting distance travelled by the apparatus and adapted to change the width of the at least one core forming member at determined points of the slipform casting process.
2. The apparatus according to claim 1, wherein the apparatus further comprises means for changing the height of the core forming member during the slipform casting process.
3. The apparatus according to claim 2, wherein the means for changing the width, or height or both only operates on part of a length of the core forming member.
4. The apparatus according to claim 1, wherein means for feeding concrete mass through the slipform casting mold, comprises a feed screw at the end of which feed screw the core forming member is connected.
5. A core forming member of a slipform casting machine for casting concrete hollow core products, which core forming member comprises at least two surface parts forming the outer surface on the length of the core forming member, and means for changing the distance between the at least two surface parts for changing the width of the core forming member; the slipform casting machine further comprising a control system for measuring a casting distance travelled by the machine and adapted to change the distance between the at least two surface parts at determined points of the slipform casting process.
6. The core forming member according to claim 5, wherein upstream ends of the at least two surface parts are connected to each other and the means for changing the width of the core forming member are adapted to move only downstream ends of the surface parts.
7. The core forming member according to claim 5, wherein the core forming member comprises at least four surface parts forming an outer surface on the length of the core forming member, and the core forming member comprises means for changing also the height of the core forming member.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) Exemplifying embodiment of the invention and its advantages are explained in greater detail below in the sense of example and with reference to accompanying drawings, where
(2) FIG. 1 shows schematically an extruder-type slipform casting apparatus of the invention,
(3) FIGS. 2A-2C show schematically a top view of a core forming member of the invention in different adjustment positions,
(4) FIGS. 3A-3C show schematically a top view of an alternative core forming member of the invention in different adjustment positions, and
(5) FIGS. 4A and 4B show schematically a back view of different core forming members of the invention.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
(6) FIG. 1 shows schematically an extruder-type slipform casting apparatus 1, which is operated during slipform casting process by feeding concrete mass from a concrete mass container 2 to feed screws 3, which feed screws extrude the concrete mass in a slipform casting mold formed by a casting bed 5, side plates 6, and a top plate 7. At the downstream end of the feed screws 3 is connected core forming members or mandrels 4, which also restricts the slipfom casting mold and form cores as longitudinal voids in the slab to be cast. The concrete mass is compacted during the slipform casting process by the rotating motion of the feed screws 3 extruding the concrete mass achieved with a drive motor 8, and by back-and-forth movement in the casting direction of the feed screws and the core forming members 4 achieved with a drive motor 9. The outer surfaces of the product to be cast are compacted by back-and-forth movement of the side plates 6, and vibrating and/or throwelling motion of the top plate achieved with a drive motor 10.
(7) FIGS. 2A-2C show schematically the core forming member 4 of the invention attached to the feed screw 3 in different adjustment positions. In the embodiment of FIGS. 2A-2C the core forming member 4 comprises two surface sections 4a and 4b forming the outer surface of the core forming member, where the surface section 4a is located partially inside the surface section 4b. Further, the surface sections 4a and 4b are connected to each other so, that the upstream ends of the surface sections define substantially constant cross-section, but the connection between the surface sections allow the downstream ends of the surface sections to be moved towards and away of each other. This can be achieved with swiveling connection between the surface sections 4a and 4b at their upstream ends, for example, and allows the core forming member to be fixed securely to the end of the feed screw 3.
(8) In the position of FIG. 2A the hollow core forming member 4 has uniform width through its length, which situation corresponds to the known core forming members.
(9) In the position of FIG. 2B the downstream ends of the surface sections 4a and 4b of the core forming member 4 are moved in a direction away from each other to provide core forming member that has gradually widening cross-section along its length. Since the downstream end of the core forming member 4 defines the cross-section of the core formed in the product to be cast, the adjustment position of FIG. 2B creates a wider core in the slab to be cast and thus also thinner web between the cores in the slab.
(10) In the position of FIG. 2C the downstream ends of the surface sections 4a and 4b of the core forming member 4 are moved in a direction towards each other to provide core forming member that has gradually thinning cross-section along its length. This adjustment position creates a thinner core in the slab to be cast and thus also thicker web between the cores in the slab.
(11) FIGS. 3A-3C show schematically a top view of an alternative core forming member 4 of the invention in different adjustment positions. The core forming member 4 and the positions shown in FIGS. 3A-3C corresponds to FIGS. 2A-2C with the exception that the core forming member comprises section 4x at the upstream end of the core forming member. This section 4x of the core forming member has substantially uniform unadjustable cross-section through its length, and thus section 4x can be used to fix the core forming member 4 at the downstream end of the feed screw 3 easily, that is similarly than connection between the feed screw and any prior art unadjustable core forming member. Further, the section 4x also makes the connection between the section 4x and the adjustable surface sections 4a and 4b much easier since the section 4x provides unrotating part for fixation and thus facilitates a better starting point for creating an adjustable connection that withstands the pressure of concrete mass inside the slipform casting mold.
(12) FIGS. 4A and 4B show schematically a back view of different hollow core forming members of the invention.
(13) In the embodiment of FIG. 4A, the core forming part 4 comprises two surface sections 4a and 4b, where the surface section 4a is partially inside the surface section 4b. The surface sections 4a and 4b are connected to each other with suitable swivel connection (not shown) at their upstream ends, and near their downstream ends the surface sections are connected to each other with suitable linear motion device 11, such as a hydraulic or pneumatic cylinder or an electric linear motor, for proving means and power to adjust the position of the downstream ends of the surface sections with respect to each other. The embodiment of FIG. 4A allows adjustment of the width of the downstream end of the core forming member 4.
(14) In the embodiment of FIG. 4B, the core forming part 4 comprises four surface sections 4a, 4b, 4c and 4d. In this embodiment the upstream ends of the surface sections 4a, 4b, 4c and 4d are connected at the overlapping area to the other overlapping surface section with a suitable swivel connection (not shown). The surface sections 4a and 4b are connected to each other near their downstream ends with suitable linear motion device 11, which allows the width of the downstream end of the core forming member 4 to be changed. The surface sections 4c and 4d are connected to other near their downstream ends with another suitable linear motion device 12, which allows the height of the downstream end of the core forming member to be changed.
(15) The specific exemplifying embodiments of the invention shown in figures and discussed above should not be construed as limiting. A person skilled in the art can amend and modify the embodiments of the core forming member of the invention described above, for example, in many evident ways within scope of attached claims. Thus the invention is not limited merely to the embodiments described above.
