Inner frame of a formwork for forming concrete products

Abstract

To provide a drawing mechanism of an inner frame (core, inner mold) of a framework for concrete product molding having excellent workability upon inner frame opening / closing and upon formwork cleaning after demolding and capable of molding a product provided with a deep bottomed or bottomless empty space into a correct shape.SOLUTION: An inner frame 1 comprises: a rigid body 2 and narrow partial frames 3a, 3b. The inside of the inner frame is erected with a driving shaft 22 vertically moving by an air cylinder 21, and the partial frames are advanced and retreated by links 6a, 6b provided at the upper part and the lower part of the partial frames. The side end parts of the inner frame body are connected to the partial frames by connection members 25, 26, 27, and the inner frame body is opened / closed by the advance / retreat operation of the partial frames. The partial frames can be guided by the side end faces of the inner frame body, the advance / retreat operation is stabilized, and opening / closing can be smoothly executed even in a tall inner frame by the vertically arranged links to remarkably reduce a work load.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inner mold (also referred to as a core, an inner mold, etc.) for forming concrete products, and more particularly to a squeezing mechanism in a cylindrical inner mold erected inside an outer mold, that is, a mechanism for retreating the circumferential surface of the inner mold from the surface of the product solidified during product demolding.

Background Art

[0002] A concrete product (hereinafter simply referred to as "product") having a vertically cylindrical cavity with at least one end open is manufactured by injecting concrete milk into the cavity formed by a bottom plate, an outer mold, and an inner mold, and then solidifying it, and lifting and removing (demolding) the solidified product from the mold. The outer mold is provided with a bottom plate and an outer mold erected on the bottom plate, and a cylindrical inner mold erected inside the outer mold.

[0003] When demolding the product, it is necessary to expand the outer mold and squeeze (reduce the diameter) the inner mold to separate it from the surface of the product. Expanding the outer mold is simple because it can be retracted outward by parallel movement or swinging. However, in a mold that cannot provide a draft angle for the inner mold, a squeezing mechanism for retracting the inner mold made of a steel plate inward must be provided.

[0004] In order to form a product with an accurate shape, it must have rigidity to withstand the pressure of the concrete milk. In order to reduce the diameter of the rigid inner mold, a structure is adopted in which the circumferential surface of the inner mold serving as the molding surface is divided into a plurality of face plates, and strip plates with a small circumferential dimension are provided at the dividing portions. After retreating the strip plates inward to form a gap, the face plates are squeezed.

[0005] For example, the inner frame described in Patent Document 1 has a strip plate at one location on the peripheral wall of the inner frame and a bent portion on the faceplate, or the faceplate is divided into two and the two are pivotally connected at a position opposite the strip plate, and the strip plate and the adjacent portion of the faceplate adjacent to the strip plate are connected by a link. In the formwork described in Patent Document 1, the strip plate moves inward by rotating a drive shaft which is a left and right screw shaft, and as this movement occurs, the faceplate bends or swings and is tightened by the connecting link.

[0006] Patent Document 2 also shows an inner frame structure in which two strip plates are provided at opposing corners of a rectangular inner frame, and it is stated that demolding is possible simply by retracting the opposing strip plates inward. Patent Document 3 also shows an inner frame structure in which the faceplate is divided into two by two strip plates, the opposing faceplates are reduced in diameter by a link (toggle link) that expands and contracts by the rotation of a drive shaft, and the adjacent parts of the strip plates and the faceplate are connected so that the strip plates move inward with a delay to the faceplate.

[0007] In the structure described above, a common mechanism for moving the strip plates or faceplates inward within the inner frame is one in which a drive shaft erected within the inner frame is connected to the strip plates or faceplates by a link such as a toggle link or a linear crank mechanism. Means for operating the link include a mechanism that uses the rotation of the drive shaft, which is a screw shaft, or a mechanism that uses the vertical movement of the drive shaft.

[0008] For example, in Patent Documents 1 and 2, a drive shaft with a right-hand thread and a left-hand screw is rotated to pull in strip plates via a V-shaped link, and in Patent Document 1, the faceplate is tightened in conjunction with the movement of the strip plates. In Patent Document 3, the faceplate is pulled in via a linear crank mechanism by the rotation of the drive shaft, and in Patent Document 4, the faceplate is tightened by moving the drive frame up and down with a cylinder. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 52-19708 [Patent Document 2] Japanese Utility Model Publication No. 7-7909 [Patent Document 3] Japanese Patent Application Publication No. 9-286017 [Patent Document 4] Patent No. 3705597 [Overview of the project] [Problems that the invention aims to solve]

[0010] As mentioned above, various types of inner frame drawing structures have been proposed, and each inner frame structure has desirable features, but there were still problems that needed to be solved, such as poor workability when opening and closing the mold, the time and effort required to clean the mold after demolding, and the fact that when molding products with large vertical dimensions, i.e., deep hollow sections, the inner frame and the product rub against each other during demolding, requiring technical skill.

[0011] For example, the inner frame described in Patent Document 1 has problems such as the entire molding surface of the inner frame not being uniformly separated from the product surface and the difficulty in opening and closing the inner frame; the inner frame described in Patent Document 2 has problems such as the faceplate not being reduced in diameter and requiring technical skill for demolding; the inner frame described in Patent Document 3 has problems such as the large surface area faceplate being reduced in diameter before the strip plates, resulting in a large amount of movement of the faceplate and the need for guide members, which increases the workload during demolding; and the inner frame in Patent Document 4 has problems such as a part of the molding surface becoming an elastic surface, which reduces the shape accuracy of the product, and because the cylinder is located at the lower end of the drive shaft, extra space is required at the bottom of the mold to obtain a large vertical stroke, and extra structural parts are required at the bottom of the mold.

[0012] This invention aims to solve the problems of the conventional devices described above, provide a concrete product molding formwork that offers excellent workability during opening and closing of the inner frame and during cleaning of the formwork after demolding, and that can accurately mold concrete products with deep, bottomed cavities or bottomless, cylindrical cavities into precise shapes. [Means for solving the problem]

[0013] This invention relates to a cylindrical inner frame 1 erected on a base plate 11 or frame 12 of a formwork for forming concrete products. The inner frame 1 of this invention is rigid and can form products with precise shapes. The inner frame 1 is provided with narrow strip plates 3a and 3b at at least one location in the circumferential direction that can be separated from the face plate 2 and retracted inward. By retracting the strip plates 3a and 3b, a gap necessary for constricting (reducing the diameter of) the face plate 2 is formed.

[0014] Within the inner frame 1, vertical drive shafts 22 and 32 are arranged, and an air cylinder 21 is provided to drive these drive shafts vertically. The strip plates 3a and 3b are connected to the drive shafts 22 and 32 by links 6a and 6b, such as telescopic links and tilting links, at their upper and lower positions, and the vertical movement of the drive shafts 22 and 32 is converted into forward and backward movement of the strip plates 3a and 3b by the links 6a and 6b.

[0015] Since the faceplate 2 is held relatively stably within the formwork, when opening and closing the formwork, the narrow strip plates 3a and 3b can be moved forward and backward ahead of the faceplate 2, allowing the strip plates 3a and 3b to be guided by the side edges of the faceplates 2a and 2b, resulting in stable movement. Furthermore, by moving the strip plates 3a and 3b forward and backward via links 6a and 6b positioned above and below them using the vertical movement of the drive shafts 22 and 32, the strip plates can be smoothly moved forward and backward even in tall inner frames using the simple structure of links 6a and 6b. In addition, by moving the drive shafts 22 and 32 up and down with the air cylinder 21, the workload when opening and closing the formwork can be significantly reduced.

[0016] The air cylinder 21 moves the drive shafts 22 and 32 up and down at a position between the upper and lower links 6a and 6b. The side ends 2e located on both sides of the strip plates 3a and 3b of the faceplate 2 are connected by connecting members 26, 27, and 33, which bring the side ends 2e closer together when the strip plates 3a and 3b are retracted inward.

[0017] This structure allows for the installation of an air cylinder with a large stroke, and even with a low-height inner frame, the spacing between the upper and lower links 6a and 6b can be widened, enabling the forward and backward movement of the strip plates 3a and 3b and the faceplate 2 connected thereto to be performed smoothly by parallel movement.

[0018] By using a rod-through type air cylinder as the air cylinder 21, in which piston rods extending from both sides of the piston inside the cylinder case pass through the cylinder case, the piston rods 22 can be used as drive shafts 22 and 32, and the drive shafts 22 and 32 can be moved up and down smoothly with a simple structure.

[0019] Furthermore, by providing strip plates 3a and 3b at opposing positions on the inner frame 1, the faceplate 2 is divided into two identical faceplates 2a and 2b facing each other. Due to the action of the upper and lower connecting members 26, 27, and 33 between the faceplates 2a and 2b and the strip plates 3a and 3b, and the action of the upper and lower links 6a and 6b connecting the strip plates 3a and 3b to the drive shafts 22 and 32, the two strip plates 3a and 3b and the faceplates 2a and 2b move forward and backward simultaneously in parallel while facing each other. As a result, the gap between the inner frame 1 and the product during demolding becomes uniform, making it possible to demold the product more reliable and easier.

[0020] In a mold for forming a product with a bottomed cavity, it is necessary to provide a top plate 4 with a periphery that contacts the upper edges of the face plate 2 and the strip plates 3a and 3b. In this case, by providing an inclined surface or inclined edge that causes the face plate 2, more preferably the face plate 2 and the strip plates 3a and 3b, to move slightly downward as the face plate 2 retracts, smooth sliding movement between the periphery of the top plate 4 and the top edge of the inner frame 1 can be achieved. The size of the top plate 4 is such that its periphery is located inside the peripheral wall of the extended face plate 2, preferably inside the peripheral wall of the retracted face plate 2. [Effects of the Invention]

[0021] By providing the inner frame according to this invention, the work load during formwork opening and closing and the work load during formwork cleaning after demolding can be reduced. In particular, products with a long length of the void provided in the product or products with a deep depth can be molded into an accurate shape. In addition, it is possible to provide a concrete product molding formwork with a simple structure and smooth opening and closing operations of the formwork.

Brief Description of the Drawings

[0022] [Figure 1] Side view showing the internal structure of the first embodiment [Figure 2] Plan view of the first embodiment shown excluding the top plate [Figure 3] Figure showing the state at the time of demolding in FIG. 1 [Figure 4] Figure showing the state at the time of demolding in FIG. 2 [Figure 5] A figure similar to FIG. 2 showing another example of the inner frame structure [Figure 6] Figure showing another example of the mounting structure of the air cylinder

Modes for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of this invention will be described with reference to the drawings. FIGS. 1 to 4 show the most preferred embodiment of the inner frame in a product molding formwork having a bottomed void. FIGS. 1 and 2 show the state at the time of mold closing (product molding), and FIGS. 3 and 4 show the state at the time of mold opening (demolding). In the figures, 1 is the inner frame, 11 is the bottom plate, and at the time of mold closing, the lower part of the peripheral wall of the inner frame abuts against the inner peripheral edge 11e of the bottom plate 11.

[0024] The inner frame 1 is a long and narrow square tubular shape with the axial direction being the vertical direction, having opposed gable-shaped face plates 2a, 2b in plan view and opposed strip plates 3a, 3b located between the edges of both, and is provided with a top plate 4. The face plates 2a, 2b and the strip plates 3a, 3b are supported by wheels 14 that roll on a plurality of short rails 13 provided on the base frame 12 for each frame. The extending direction of the rails 13 is the opposing direction of each of the face plates 2a, 2b and the strip plates 3a, 3b, and the upper surface thereof is slightly inclined in the direction where the inner side is lower.

[0025] The top plate 4 is sized to be inside the retracted position of the molded surfaces of the face plates 2a and 2b when narrowed, and is fixed to the upper ends of two columns 15 erected on the base frame 12 via beams 16 and brackets 17.

[0026] A rod-through type air cylinder 21 is fixed to the column 15 at an intermediate height via a mount 18. The ends of rods 22 extending from both ends of the cylinder case are connected to strip plates 3a and 3b via opening and closing links 6a and 6b that extend in opposing directions to the strip plates 3a and 3b, and horizontal pins 23 and 24 perpendicular to the opposing direction. Each link 6a and 6b is equipped with a threaded rod 6e for fine adjustment of its length.

[0027] With the above structure, the strip plates 3a and 3b are connected to the piston rod 22 at two points, above and below them, via links 6a and 6b. As the piston rod 22 moves up and down, the links 6a and 6b swing, causing the strip plates to move closer together and further apart. When separated, they fit between the edges of opposing faceplates, creating a closed state. When brought closer together, they form a gap between the edges of opposing main frame sections, allowing the faceplates 2a and 2b to move inward. In other words, the piston rod 22 acts as the drive shaft for opening and closing the inner frame 1.

[0028] The strip plates 3a and 3b and the side ends 2e of the adjacent face plates 2a and 2b are connected by a connecting pin 26 erected on a pin plate 25 fixed to one side and a guide plate 27 fixed to the other side. The guide plate 27 is provided with a retraction-side guide edge 28 that contacts the connecting pin 26 when the strip plates 3a and 3b retract, i.e., when the strip plates 3a and 3b move toward each other, causing the face plates 2a and 2b to retract with a delay. When the strip plates 3a and 3b advance, the side edges of the strip plates 3a and 3b push the side edges of the face plates 2a and 2b, causing the face plates 2a and 2b to advance.

[0029] Next, the operation of the inner frame described above will be explained. When demolding a product molded in the closed state shown in Figures 1 and 2, lowering the piston rod 22 causes links 6a and 6b to tilt as shown in Figure 3, retracting the opposing strip plates 3a and 3b. In conjunction with this retraction of the strip plates 3a and 3b, sliding contact between the connecting pin 26 and the retraction-side guide edge 28 causes the faceplates 2a and 2b to retract, constricting the inner frame 1 and creating a uniform gap between the faceplates 2a and 2b and the surface of the product. Since the strip plates 3a and 3b have retracted before the faceplates 2a and 2b, the product can be easily demolded by lifting it without sliding it against the inner frame.

[0030] After demolding, the formwork is usually cleaned to remove molded slag that has leaked and hardened between the strip boards 3a and 3b and the face panels 2a and 2b and the top plate 4. However, the contact surfaces between the edges of the strip boards 3a and 3b and the face panels 2a and 2b, as well as the contact surface with the top plate 4, can be made to have a certain width, and sealing rubber 7 or the like can be attached as needed, thereby reducing concrete milk leakage and easing the effort required for cleaning.

[0031] After cleaning is complete, moving the piston rod upward causes the strip plates 3a and 3b to advance. The faceplate advances to the mold closing position faster than the advancement of the strip plates, and the strip plates 3a and 3b are fitted into the gap between its edges, thus closing the mold.

[0032] During mold opening and closing, the strip plates 3a and 3b are connected to the piston rod 22, which is the drive shaft, by links 6a and 6b at their upper and lower ends and move back and forth synchronously. The face plates 2a and 2b are connected to the strip plates 3a and 3b at their upper and lower side ends 2e and move back and forth synchronously. As a result, the circumferential surface of the inner frame 1 is narrowed in parallel, and even with a tall inner frame, a uniform gap can be formed between it and the product surface during demolding.

[0033] Furthermore, as the strip plates 3a, 3b and face plates 2a, 2b move in the retraction direction, the strip plates 3a, 3b and face plates 2a, 2b, which are supported by the rails 13 via the wheels 14, move slightly downward. This loosens the contact between the top plate 4 and the upper edges of the strip plates 3a, 3b and face plates 2a, 2b, and the top plate 4 ensures the smooth movement of the strip plates 3a, 3b and face plates 2a, 2b.

[0034] The above embodiment is a structure in which the faceplate is divided into two and the inner frame is opened and closed by the parallel movement of each faceplate. However, it is also possible to use a single strip plate and provide a bent portion on the opposite side to narrow it. Figure 5 is a schematic diagram showing the main part of such an inner frame structure, in which a bent portion 2f made of elastic steel plate is provided on the part opposite to the strip plate 3a. The strip plate 3a is connected to the edge of the faceplate 2 by a connecting link 33.

[0035] The drive shaft 32, located within the inner frame, is connected to the strip plate 3a by a short opening / closing link 6a, and to a position adjacent to the bent portion 2f of the faceplate 2 via a connecting plate 34 by a longer opening / closing link 6b. A gap 35 is provided at the connection between the connecting plate 34 and the faceplate 2 so as not to hinder the smooth bending operation of the bent portion 2f.

[0036] In the above structure, when the drive shaft 32 is driven upward or downward from the mold-closed state where the opening and closing links 6a and 6b are in the horizontal position, the links 6a and 6b tilt, retracting the strip plate 3a and simultaneously retracting the faceplate 2 at both sides of the bent portion 2f. At this time, the strip plate 3a, which is connected to the drive shaft 32 by the shorter link 6a, retracts more than the faceplate 2, and the faceplate 2 moves toward the strip plate 3a and is pulled and squeezed by the connecting link 33 as the strip plate 3a retracts. As a result, a substantially uniform gap is formed between the inner frame 1 and the product when demolding.

[0037] As shown in the embodiment described above, the structure can be simplified by using a through-rod type cylinder 21 as the cylinder that moves the drive shaft 32 up and down. When using a general cylinder 31 in which the piston rod extends from only one end of the cylinder case, as shown in Figure 6, the drive shaft 32 can be connected to the piston rod 38 of the cylinder 31 by a connecting member 37 at an intermediate position between the connection parts 36, 36 with the upper and lower opening and closing links 6a, 6b, and the drive shaft 32 can be moved up and down. In Figure 6, two cylinders are arranged to balance the left and right vertical power, but when a cylinder is provided on only one side, a sliding bearing should be provided to guide the drive shaft 32 in order to prevent excessive force from acting on the cylinder. [Explanation of Symbols]

[0038] 1 Inner frame 2 face plates 2e Side edge 3a, 3b strip board 4 Top plate 6a, 6b Open / Close Links 11 Bottom plate 12-frame 21 Air Cylinder 22 Piston Rod 32 drive shafts 26 connecting pins 27 Guide plate 33 Connecting links

Claims

1. A cylindrical inner frame erected on the bottom plate or base frame of a formwork for forming concrete products, The inner frame surface is provided with a narrow strip plate that is detachable from the rigid faceplate at at least one location in the circumferential direction, In the inner frame comprising a drive shaft erected within the inner frame, an air cylinder for moving the drive shaft up and down, and a link mechanism for moving the strip plate forward and backward when the drive shaft moves up and down, The air cylinder is fixed to a column erected on the base plate or frame, and the link mechanism connects the drive shaft and the strip plate at the upper and lower positions of the air cylinder. The panel comprises adjacent portions located on both sides of the strip plate and a connecting member that connects the strip plate and brings the adjacent portions on both sides closer together when the strip plate moves inward. Inner frame for a mold used to form concrete products.

2. The inner frame according to claim 1, wherein the air cylinder is a rod-through type air cylinder, and the drive shaft is the piston rod of the rod-through type air cylinder.

3. The inner frame according to claim 1 or 2, wherein two of the strip plates are provided at opposing positions on the inner frame, and the two strip plates move forward and backward in synchronous motion due to the vertical movement of the drive shaft.

4. An inner frame for a concrete product molding formwork that molds a concrete product having a bottomed cavity, wherein a top plate for molding the bottom surface of the cavity is provided in contact with the upper end of the peripheral wall of the inner frame, and the inner frame is provided with an inclined surface or inclined edge that slightly moves the face plate downward when the inner frame is retracted.

Images