JP6186232B2 - Concrete strength test formwork - Google Patents

Description

  The present invention relates to a mold for forming a specimen for a concrete strength test.

  Regarding the strength of concrete, various test methods are defined in JIS (for example, compressive strength test of JIS A 1108 concrete). The test is carried out by curing the concrete to create a structure with a certain shape and measuring the strength of this structure. The method of making this structure (hereinafter referred to as a specimen) is also JIS A 1132 etc. It is prescribed as

  The specimen is manufactured by filling the formwork with concrete to be tested and removing the formwork after curing. In JIS, the shape of the specimen is assumed to be cylindrical, and its height is assumed to be twice the diameter. Therefore, a mold that satisfies this rule is used. As for the formwork, JIS A 5308 “Ready mixed concrete” Annex E (normative), there is a prescription for precision of the formwork in the attached file of the lightweight formwork. Several types of molds with different shapes are commercially available as molds that satisfy these regulations.

  Conventionally, metal molds manufactured by casting have been used as such molds, but they are heavy and difficult to carry, and can be reused after testing, but they are stuck to the molds. The work of removing concrete pieces was a burden.

  Therefore, the present inventors have proposed a plastic mold that can be easily broken and the specimen can be taken out (see Patent Document 1). Furthermore, the present inventor has proposed a mold frame provided with a stopper portion for preventing deformation of a breaking jig used for breaking a plastic mold frame (see Patent Document 2).

  The plastic mold has a cylindrical shape having a bottom portion, and a fragile portion is formed in the longitudinal direction of the cylindrical portion. The fragile portion is a portion that breaks when the concrete specimen is taken out of the formwork, and is formed thinner than the other cylindrical portions. Moreover, a pair of convex wall was provided so that the weak part may be pinched | interposed.

  The work of breaking the mold is to break the cylindrical part into two along the weak part by pushing the pair of bar parts of the break jig between the convex walls so as to push the weak part of the form. It is. The breaking operation at this time is considered to be due to brittle fracture due to an impact load at the fragile portion because the breaking jig is hit from above with a hammer or the like and pushed between the convex walls.

  However, for example, when the shape of the cylindrical portion exceeds 200 mm, the fragile portion also becomes longer according to the height of the cylindrical portion, and there has been an event that the rupture operation does not break along the fragile portion so far. Some have been confirmed.

  FIG. 12 is a photograph for explaining a fractured state of a conventional concrete strength test formwork. In order to push the breaking jig between the upper end of the mold and the convex wall, it breaks along the fragile part near the upper end of the mold, but it breaks diagonally away from the fragile part in the middle of the cylindrical part . Thus, in the case where it does not break along the fragile portion, the concrete specimen remains in the mold cylinder left near the bottom, and the specimen is placed in the axial direction of the remaining cylinder. There is a hassle that must be pulled out.

JP 2005-345169 A JP 2013-125007 A

  Accordingly, an object of the present invention is to provide a concrete strength test form that can be more reliably broken along the fragile portion during the breaking operation.

[Application Example 1]
The concrete strength test form according to this application example is
A plastic cement material strength test mold having a cylindrical part having one end opened and a bottom part closing the other end of the cylindrical part,
On the outer surface of the cylindrical portion, a fragile portion extending along the axial direction from one end to the other end of the cylindrical portion, and a pair of convex walls facing each other with the fragile portion interposed therebetween are formed.
The vulnerable part is
A thin part thinner than the cylindrical part other than the weak part,
A first groove formed in a concave shape from the outer surface at a midpoint in the width direction of the thin portion;
A second groove and a third groove that are formed in a concave shape from the outer surface on both sides of the first groove in the thin-walled portion, and make it difficult for the molten plastic to flow when molding a mold,
It is characterized by having.

  According to this application example, in order to form the second groove and the third groove, the narrowed portion is formed in the mold. The constricted portion makes it difficult for the molten plastic to flow at the time of molding, so that a weld line can be formed in the vicinity of the first groove in the thin portion where the molten plastic flows. Therefore, according to this application example, when the formwork is broken, it can be more reliably broken along the fragile portion, and the concrete specimen can be easily taken out of the formwork.

[Application Example 2]
In the above concrete strength test form,
The fragile portion has an inclined surface inclined from the outer surface toward the thin-walled portion,
The first groove, the second groove, and the third groove are formed such that the width gradually decreases inward from the outer surface,
The second groove and the third groove may be formed near both ends in the width direction of the thin portion.

  According to this application example, the flow of the plastic melted at the time of molding the mold can be made gentle by the inclined surface. Moreover, since the width | variety of a 1st groove | channel, a 2nd groove | channel, and a 3rd groove | channel narrows gradually toward an inner side from an outer surface, a flow can be slowed without stopping the flow of the molten plastic at the time of shaping | molding of a formwork. Furthermore, since there are the second groove and the third groove near both ends in the width direction of the thin portion, the molten plastic whose flow is slowed down by the inclined surface, the second groove, and the third groove easily joins in the thin portion. Therefore, according to this application example, when the formwork is broken, it can be more reliably broken along the fragile portion, and the concrete specimen can be easily taken out of the formwork.

[Application Example 3]
In the above concrete strength test form,
The first groove may be deeper than the second groove and the third groove.

  According to this application example, by making the first groove deeper than the second groove and the third groove, the flow of the most melted plastic in the first groove during molding of the mold is slowed, and in the vicinity of the first groove. It becomes easier for molten plastic to merge. In addition, the first groove of the deepest groove is the thinnest and tends to be a starting point of destruction. Therefore, according to this application example, when the formwork is broken, it can be broken along the first groove, and the concrete specimen can be easily taken out of the formwork.

[Application Example 4]
In the above concrete strength test form,
The bottom portion has a bottom fragile portion continuous with the fragile portion, and a bottom opening that opens in the middle of the bottom fragile portion,
The bottom weak part is
A bottom thin portion thinner than the bottom portion other than the bottom weak portion, and
A first bottom groove formed in a concave shape from the bottom surface at a midpoint in the width direction of the bottom thin portion;
A second bottom groove and a third bottom groove formed in a concave shape from the bottom surface in both sides of the first bottom groove in the bottom thin portion;
Can have.

  According to this application example, by forming a fragile portion similar to the cylindrical portion at the bottom, when the mold is broken, the bottom can be more reliably broken along the fragile portion. The specimen can be easily removed from the formwork.

  According to the concrete strength test form according to the present invention, when the form is broken, it can be more reliably broken along the fragile portion, and the concrete specimen can be easily taken out of the form. .

It is a perspective schematic diagram of a concrete strength test formwork and a fracture jig concerning one embodiment of the present invention. It is a front view of the form for concrete strength testing concerning one embodiment of the present invention. FIG. 3 is a partially enlarged view of an AA cross section in FIG. 2. It is a partially expanded view of the BB cross section in FIG. FIG. 3 is a partially enlarged view of a CC cross section in FIG. 2. It is a bottom view of the formwork for concrete strength tests concerning one embodiment of the present invention. It is DD sectional drawing in FIG. 6 for demonstrating the structure of a bottom part. It is a partially expanded view of the EE cross section in FIG. 6 for demonstrating the structure of a bottom part. It is a figure explaining the state which takes out a specimen from the form for concrete strength testing concerning one embodiment of the present invention. It is a partial enlarged view of CC section in a modification. It is a partial enlarged view of the EE cross section in a modification. It is a photograph explaining the fracture | rupture state of the conventional concrete strength test formwork.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

A concrete strength test form according to an embodiment of the present invention is a plastic cement material strength test form having a cylindrical part having one end opened and a bottom part closing the other end of the cylindrical part. The outer surface of the cylindrical portion is formed with a fragile portion extending in the axial direction from one end to the other end of the cylindrical portion, and a pair of convex walls facing each other with the fragile portion interposed therebetween. The thin portion is thinner than the cylindrical portion other than the fragile portion, a first groove formed in a concave shape from the outer surface at a midpoint in the width direction of the thin portion, and in the thin portion, It has a second groove and a third groove which are formed in a concave shape from the outer surface on both sides of one groove and make it difficult for molten plastic to flow when the mold is formed.

  FIG. 1 is a schematic perspective view of a concrete strength test mold and a breaking jig according to an embodiment of the present invention. FIG. 2 is a front view of a concrete strength test form according to an embodiment of the present invention. FIG. 3 is a partially enlarged view of the AA cross section in FIG. 2. 4 is a partially enlarged view of the BB cross section in FIG. FIG. 5 is a partially enlarged view of the CC cross section in FIG. 2. FIG. 6 is a bottom view of a concrete strength test mold according to an embodiment of the present invention. 7 is a cross-sectional view taken along the line DD in FIG. 6 for illustrating the structure of the bottom. FIG. 8 is a partially enlarged view of the EE cross section in FIG. 6 for explaining the structure of the bottom. FIG. 9 is a diagram illustrating a state in which a specimen is taken out from the concrete strength test form according to the embodiment of the present invention.

  As shown in FIG. 1, a concrete strength test mold 70 is a plastic cement material having a cylindrical portion 1 having an opening 10 at one end and a bottom portion 5 closing the other end of the cylindrical portion 1. It is a form for strength testing.

  A flange portion 2 is formed in the opening 10. The flange portion 2 is a bowl-shaped portion formed in an annular shape along the edge of the opening 10 of the cylindrical portion 1.

  Two jig holes 20 are formed in the flange portion 2. The jig holes 20 are provided at intervals of 180 degrees in the flange portion 2, and are symmetrical positions with respect to the central axis of the cylindrical portion 1. The jig hole 20 is substantially rectangular. A rod portion 92 of the breaking jig 9 described later is inserted into the jig hole 20. The flange portion 2 may have a slightly larger width at the portion where each jig hole 20 is formed.

  On the outer surface 11 of the cylindrical portion 1, a weak portion 3 extending along the axial direction from an opening 10 at one end of the cylindrical portion 1 to a bottom portion 5 at the other end, and a pair of convexes facing each other across the weak portion 3 A wall 4 is formed.

  The fragile portion 3 is a portion where the thickness is partially reduced by forming a groove in the outer surface 11 of the cylindrical portion 1. The fragile portion 3 is formed to extend in the axial direction of the cylindrical portion 1 from the jig hole 20 toward the bottom portion 5, and is provided in at least two places in the cylindrical portion 1.

  The convex wall 4 is a wall-shaped part protruding outward from the outer surface 11 of the cylindrical portion 1. The convex wall 4 has an upper end connected to the flange portion 2 and extends to a height position in the middle of the cylindrical portion 1. The spacing between the paired convex walls 4 is slightly smaller than the width of the thickest portion 93 of the rod portion 92 of the breaking jig 9. The length of the convex wall 4 in the height direction is substantially the same as the length of the bar portion 92 of the breaking jig 9.

  The bottom portion 5 is provided with a bottom weak portion 6 extending so as to linearly connect positions corresponding to the lower ends of the pair of weak portions 3 and 3 in the cylindrical portion 1. A bottom opening 50 is formed in the middle of the bottom weakened portion 6.

  The breaking jig 9 is integrally formed of a metal such as steel, and is a pair of bar portions 92 extending linearly and a plate-like portion connecting the base end portions of these bar portions 92 91. Each bar portion 92 is inserted into the jig hole 20 in a state in which each parallel inner surface thereof is close to each fragile portion 3 on the outer surface 11 of the cylindrical portion 1.

Further, the bar portion 92 has a thickest portion 93. The tip of the rod portion 92 is formed so that its width is slightly narrower than the circumferential dimension of the jig hole 20 and the interval between the opposing convex walls 4, 4, and can be inserted into the jig hole 20 as it is. The thickest portion 93 is formed on the proximal end side of the rod portion 92, and is formed so as to gradually spread linearly on both sides in the width direction from the distal end side to the proximal end side of the rod portion 92. The width of the thickest portion 93 is formed so as to gradually increase from the width of the tip of the rod portion 92 to 2 to 4 times the circumferential dimension of the jig hole 20 (the interval between the opposing convex walls 4). The plate-like portion 91 is formed in a flat shape that is easy to hit with a hammer or the like when the formwork 70 is broken.

  As shown by the arrows in FIG. 2, when forming the mold 70, molten plastic is introduced from both sides of the bottom 5 sandwiching the bottom fragile portion 6 and injection molding is performed. Although not shown, the mold used for injection molding of the mold 70 has a cavity having the same shape as the mold 70, and has, for example, two gates at corresponding positions on the bottom 5 (see the gate G in FIGS. 6 and 7). ) Is provided. The two gates are provided at positions corresponding to positions that divide the cylindrical portion 1 in the mold into two equal parts in the circumferential direction. The molten plastic is injected simultaneously from these two gates. Thus, the molten plastic injected into the mold from the two gates has two flows, spreads into the cavity forming the bottom 5 and flows into the cylindrical part 1. These two flows merge in the vicinity of the bottom weak part 6 in the bottom part 5 and in the vicinity of the weak part 3 in the cylindrical part 1, and a weld line is formed at each position divided into two equal parts in the circumferential direction in the cylindrical part 1. The

  The weld line may not appear on the appearance. The weld line has a fragile structure with low mechanical strength inside. In particular, when a fiber reinforced plastic is used, since there are few fibers to reinforce across the weld line, a region with low mechanical strength is formed on the weld line.

  Also, the molten plastic flows quickly because the wide part of the cavity is easy to flow, and flows slowly because the narrow part of the cavity is difficult to flow. That is, since the width of the cavity is narrow in the thin portion such as the fragile portion 3 and the bottom fragile portion 6, the flow of the molten plastic is slower than the other portions during the injection molding.

  As shown in FIGS. 3 to 5, the fragile portion 3 has a shape in which a groove is formed on the outer surface 11 of the cylindrical portion 1 at a position between the pair of convex walls 4. The fragile portion 3 includes a thin portion 32 thinner than the cylindrical portion 1 other than the fragile portion 3, a first groove 31 a formed in a concave shape from the outer surface 11 of the thin portion 32 at a midpoint in the width direction of the thin portion 32, and a thin wall A second groove 31b and a third groove 31c that are formed in a concave shape from the outer surface 11 of the thin-walled portion 32 on both sides of the first groove 31a and make it difficult for molten plastic to flow when the mold 70 is molded. And having.

  By having such a fragile portion 3, a narrowed portion is formed in the mold for molding the second groove 31 b and the third groove 31 c, and this narrowed portion makes it difficult for the molten plastic to flow during molding. Therefore, the melted plastic whose flow has slowed slowly fills the thin portion 32, and the melted plastic flows merge in the vicinity of the first groove 31a to form a weld line. Therefore, according to such a formwork 70, when breaking the formwork 70, it can be more reliably broken along the fragile portion 3, and the concrete specimen can be easily taken out of the formwork. .

  The fragile portion 3 has an inclined surface 34 that is inclined from the outer surface 11 toward the thin portion 32. The inclined surfaces 34 are formed at both ends of the thin portion 32 in the width direction. By having such an inclined surface 34, the thickness of the cylindrical portion 1 is gradually reduced, and the flow of the molten plastic can be moderated when the mold 70 is molded.

The first groove 31a, the second groove 31b, and the third groove 31c are formed so that the width gradually decreases inward from the outer surface 11 in the thin portion 32. Since the widths of the first groove 31a, the second groove 31b, and the third groove 31c gradually narrow inward from the outer surface 11, the flow can be slowed without stopping the flow of the melted plastic when the mold 70 is molded. . Further, when the first groove 31a, the second groove 31b, and the third groove 31c have V-shaped cross sections, stress concentration occurs in the deepest part of the groove, and the groove can be easily broken. The first groove 31a, the second groove 31b, and the third groove 31c may have the same shape or different shapes.

  The second groove 31b and the third groove 31c can be formed near both ends of the thin portion 32 in the width direction. A narrowed portion formed by the second groove 31b and the third groove 31c is formed near both ends in the width direction of the thin-walled portion 32. When the mold 70 is formed, the flow of molten plastic is caused by the narrowed portion formed by the second groove 31b and the third groove 31c. Becomes slow, and it becomes easy to merge in the thin portion 32.

  The second groove 31b and the third groove 31c are formed at positions that are line-symmetric with respect to the first groove 31a.

  The two fragile parts 3 are in line-symmetrical positions (positions at an interval of 180 degrees) with the central axis of the cylindrical part 1 as the symmetry axis. In particular, the deepest portion of the first groove 31 a is located symmetrically with respect to the central axis of the cylindrical portion 1 and is on the same straight line in the radial direction of the cylindrical portion 1.

  The convex wall 4 is made to act in the direction which widens the space | interval with the convex wall 4 which opposes by contacting with the rod part 92 of the fracture | rupture jig | tool 9. FIG. The force acting in the direction in which the interval between the opposing convex walls 4 is increased acts as a tensile force on the fragile portion 3, and the cylindrical portion 1 breaks into two along the fragile portion 3.

  The convex wall 4 has a stopper portion 41 at an outer end portion when viewed from the cylindrical portion 1. The stopper portion 41 is a protruding plate piece that protrudes toward the opposing convex wall 4, and has a shape that bends the end portions of the convex walls 4 to the sides facing each other. Although the stopper part 41 extends from the upper end part (continuous part with the flange part 2) of each convex wall 4, it is not formed over the full length of each convex wall 4, but extended to the height position in the middle It has become. However, it may extend over the entire length of each convex wall 4. The stopper portion 41 can prevent the breaking jig 9 from being deformed so as to spread outward with respect to the cylindrical portion 1.

  As shown in FIG. 6, the bottom 5 has a bottom fragile portion 6 that is continuous with the fragile portion 3 provided in the cylindrical portion 1, and a bottom opening 50 that opens in the middle of the bottom fragile portion 6.

  The bottom opening 50 is at the center of the circular bottom 5, and the bottom weakened portion 6 is formed on a straight line passing through the bottom opening 50 and crossing the bottom 5. On the bottom 5, a trace of the gate G into which the plastic melted when the mold 70 is injection-molded is left. The gate G is a point target inward centered on the bottom opening 50 and is in a line-symmetrical position with the bottom weakened portion 6 as an axis of symmetry.

  As shown in FIG. 7, a metal plate 52 is disposed on the inner side of the bottom portion 5 (on the cylindrical portion 1 side) with a predetermined distance from the bottom portion 5. The metal plate 52 is placed on the step portion 51 provided over the entire circumference at the connection portion between the bottom portion 5 and the cylindrical portion 1, and is bonded with the adhesive S provided between the bottom portion 5. . The adhesive S is preferably not provided on the bottom opening 50 and the bottom fragile portion 6 in order to easily break the mold 70.

  When the concrete is poured into the mold 70, the metal plate 52 has a role of preventing the deformation of the bottom 5 formed relatively thin and closing the bottom opening 50.

As shown in FIG. 8, the bottom fragile portion 6 includes a bottom thin portion 62 thinner than the bottom portion 5 other than the bottom fragile portion 6, and a concave portion formed from the bottom surface 53 at the midpoint in the width direction of the bottom thin portion 62. 1 bottom groove 61a;
Within the bottom thin part 62, it has the 2nd bottom groove 61b and the 3rd bottom groove 61c which were formed in the concave shape from the bottom face 53 on both sides of the 1st bottom groove 61a.

  Since the 1st bottom groove 61a, the 2nd bottom groove 61b, and the 3rd bottom groove 61c are the same cross-sectional shapes as the 1st groove | channel 31a, the 2nd groove | channel 31b, and the 3rd groove | channel 31c, description here is abbreviate | omitted.

  Thus, by forming the bottom fragile portion 6 similar to the cylindrical portion 1 in the bottom portion 5, when the formwork 70 is broken, the bottom portion 5 is more surely extended along the fragile portion 3 and the bottom fragile portion 6. It is possible to break, and the concrete specimen can be easily taken out from the mold 70.

  The bottom fragile portion 6 has a bottom inclined surface 64 that is inclined from the bottom surface 53 toward the bottom thin portion 62. The bottom inclined surfaces 64 are formed at both ends of the bottom thin portion 62 in the width direction. By having such a bottom inclined surface 64, the thickness of the bottom portion 5 is gradually reduced, and the flow of molten plastic at the time of molding the mold 70 can be moderated.

  As the formwork 70, a plastic material can be selected in consideration of impact resistance and shape stability. For example, the mold 70 can be made of polybutylene terephthalate (PBT) resin to which glass fiber is added as a reinforcing material. Glass fiber reinforced PBT resin is excellent in impact resistance and shape stability, and also has a large amount of market distribution, so it is also superior in cost competitiveness, and as a material for concrete strength test formwork. Is preferred.

  Injection molding of the mold 70 is performed by injecting molten plastic, for example, reinforced PBT resin, into a gate which is an injection port provided in a mold having a cavity in the shape of the mold 70, and cooling in the mold for a predetermined time. After the reinforced PBT resin is hardened, the molding is performed by taking out the molded frame 70 from the mold.

  Normally, when molding a simple bottomed cylindrical shaped body, plastic is injected from one gate provided at the center of the bottom, and after filling the entire bottom with molten plastic, it flows into the cylindrical part, The molten plastic progresses almost evenly into the upper opening in a cylindrical shape. Therefore, in such a case, if there is no portion where the plastic wraps slowly, the weld line is hardly formed in the cylindrical portion.

  In this embodiment, the gate G is provided at two locations with the bottom weak portion 6 sandwiched between the bottom 5 of the mold 70. It is expected that the melted plastic injected simultaneously from the two gates G spreads in a circle around each gate G and merges in the vicinity of the bottom weak part 6. Then, the flow of the plastic melted from the bottom portion 5 to the cylindrical portion 1 progresses, and it is expected that the two flows also merge into the opening 10 in the vicinity of the fragile portion 3.

  The portion where the melted plastics merge is relatively stable in the vicinity of the bottom fragile portion 6 at the bottom portion 5 near the gate G, but the fragile portion in the cylindrical portion 1 after flowing away from the gate G and bent in a right angle. There is a high possibility that it will deviate from 3.

  However, by adopting the fragile portion 3 in the present embodiment, it is possible to easily form a weld line where the flow of the molten plastic merges in the vicinity of the first groove 31a in the thin portion 32. And the certainty can be made still higher by employ | adopting the bottom part weak part 6 for the bottom part 5. FIG.

More specifically, the fragile portion 3 in FIG. 5 will be described as an example. The flow of molten plastic approaches the fragile portion 3 with two flows from the left and right of the fragile portion 3 in FIG. First, the cavity forming the fragile portion 3 is gradually narrowed by the inclined surface 34 (the space between the mold surfaces), thereby slowing the flow of the molten plastic. Furthermore, the flow of the molten plastic that has reached the thin portion 32 is slowed down in the narrowed portion of the cavity formed so as to be constricted by the second groove 31b and the third groove 31c formed near both ends of the thin portion 32. Naturally, the melted plastic hardly flows even by the narrow cavity of the thin portion 32, so that the cavity is slowly filled up to the first groove 31a.

  By adopting such a configuration, for example, even when the flow on the right side of the fragile portion 3 in FIG. 5 reaches the fragile portion 3 in the CC cross section slightly earlier than the flow on the left side, the fragile portion 3 Can be merged in the vicinity of the first groove 31a by the slow molten plastic flow in the fragile portion 3 without flowing to the left side.

  The weld line does not need to be formed at the same position as the first groove 31a, and may be formed in the vicinity of the first groove 31a. Since stress concentrates on the deepest part of the first groove 31a, that is, the thinnest part, if there is a weld line with low mechanical strength in the vicinity of the first groove 31a, the fracture occurs in the vicinity of the first groove 31a. Because.

  The process of taking out the specimen 100 from the mold 70 will be described with reference to FIGS. 1 and 9.

  First, the formwork 70 shown in FIG. 1 is filled with concrete, and the concrete is made uniform by hitting it with a wooden mallet. At this time, the opening 10 at one end of the cylindrical portion 1 is closed with a dedicated lid or the like. After a certain period of time, when the concrete is hardened, the breaking jig 9 is inserted into the jig hole 20 with the bar portion 92 of the mold 70, and the plate portion 91 is hit with a hammer or the like up to the thickest portion 93 of the bar portion 92. Push into the jig hole 20. When the opposing convex wall 4 is expanded by the bar portion 92, the fragile portion 3 is broken. At this time, even if the rod portion 92 of the breaking jig 9 is to be deformed so as to open outward, such plastic deformation is restricted because of the stopper portion 41.

  The breakage of the fragile portion 3 propagates from the opening 10 side to the bottom portion 5 side in an instant along the first groove 31a with almost no ductile fracture, resulting in brittle fracture. In particular, in the formwork 70 according to the present embodiment, a weld line is present in the vicinity of the first groove 31a due to the second groove 31b and the third groove 31c. Further, by breaking along the fragile portion 3, the breakage easily propagates to the bottom fragile portion 6 formed in a portion continuous to the fragile portion 3. Furthermore, since the bottom opening 50 is continuous with the bottom weakened portion 6, the breakage is easily propagated.

  For this reason, as shown in FIG. 9, the specimen 100 can be easily extracted from the mold 70 that is broken into two semi-cylindrical shapes.

  Further, three or more fragile portions 3 may be provided in the circumferential direction with respect to the cylindrical portion 1. For example, when three weak parts 3 are provided in the circumferential direction of the cylindrical part 1, three gates can be provided, and when four weak parts 3 are provided in the circumferential direction of the cylindrical part 1, the gates are provided. It can be provided at four locations.

(Modification)
FIG. 10 is a partially enlarged view of a CC cross section in the modified example. FIG. 11 is a partially enlarged view of the EE cross section in the modified example.

  As shown in FIG. 10, as a modification of the present embodiment, in the cylindrical portion 1 of the mold 70, the first groove 31a can be a deeper groove than the second groove 31b and the third groove 31c. As shown in FIG. 11, in the bottom part 5 of the mold 70, the first bottom groove 61a can be deeper than the second bottom groove 61b and the third bottom groove 61c.

  By making the first groove 31a deeper than the second groove 31b and the third groove 31c, the flow of the plastic most melted in the first groove 31a during the molding of the mold 70 is slowed down, and melted in the vicinity of the first groove 31a. The plastics that have been added are easy to merge. Further, the first groove 31a of the deepest groove is the thinnest and is likely to be a starting point of destruction. Further, the same effect can be obtained with respect to the first bottom groove 61a of the bottom portion 5. Therefore, when the mold 70 is broken, it can be broken along the first groove 31a and the first bottom groove 61a, and the concrete specimen 100 can be easily taken out of the mold 70.

  In addition, by using a glass fiber reinforced PBT resin, the mold 70 is excellent in terms of impact resistance and shape stability as described above, but in the weld line that is a merged portion of the two flows, Glass fiber is difficult to reinforce the weld line. Therefore, not only the glass fiber reinforced PBT resin but also other fiber reinforced plastics, the mechanical strength in the weld line and the mechanical strength of the other parts are easily different, and the fragile portion 3 and the bottom fragile portion 6 It is advantageous in that it is easy to break along.

  In the present invention, the term “concrete” needs to be understood in a broad sense. Mortar is hardened without mixing gravel into cement and is distinct from concrete, but the formwork structure of the present invention can also be used for strength testing of mortar. Is also included.

  As mentioned above, although this embodiment or the modification was demonstrated, this invention is not limited to these this embodiment or a modification, It is possible to implement in a various aspect in the range which does not deviate from the summary.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 Cylindrical part, 2 flange part, 3 weak part, 4 convex wall, 5 bottom part, 6 bottom weak part, 9 breaking jig, 10 opening, 20 jig hole, 11 outer surface, 31a 1st groove | channel, 31b 2nd groove | channel, 31c 3rd groove, 32 Thin part, 34 Inclined surface, 41 Stopper part, 50 Bottom opening, Step part 51, 52 Metal plate, 53 Bottom, 61a 1st bottom groove, 61b 2nd bottom groove, 61c 3rd bottom groove, 62 bottom thin part, 64 bottom inclined surface, 70 mold, 91 plate-like part, 92 bar part, 93 thickest part, 100 specimen, G gate, S adhesive

Claims (4)

A plastic cement material strength test mold having a cylindrical part having one end opened and a bottom part closing the other end of the cylindrical part,
On the outer surface of the cylindrical portion, a fragile portion extending along the axial direction from one end to the other end of the cylindrical portion, and a pair of convex walls facing each other with the fragile portion interposed therebetween are formed.
The vulnerable part is
A thin part thinner than the cylindrical part other than the weak part,
A first groove formed in a concave shape from the outer surface at a midpoint in the width direction of the thin portion;
A second groove and a third groove that are formed in a concave shape from the outer surface on both sides of the first groove in the thin-walled portion, and make it difficult for the molten plastic to flow when molding a mold,
A form for testing concrete strength, comprising: In claim 1,
The fragile portion has an inclined surface inclined from the outer surface toward the thin-walled portion,
The first groove, the second groove, and the third groove are formed such that the width gradually decreases inward from the outer surface,
The second groove and the third groove are formed in the vicinity of both ends in the width direction of the thin portion, and the concrete strength test form. In claim 1 or 2,
A concrete strength test form, wherein the first groove is deeper than the second groove and the third groove. In any one of Claims 1-3,
The bottom portion has a bottom fragile portion continuous with the fragile portion, and a bottom opening that opens in the middle of the bottom fragile portion,
The bottom weak part is
A bottom thin portion thinner than the bottom portion other than the bottom weak portion, and
A first bottom groove formed in a concave shape from the bottom surface at a midpoint in the width direction of the bottom thin portion;
A second bottom groove and a third bottom groove formed in a concave shape from the bottom surface in both sides of the first bottom groove in the bottom thin portion;
A form for testing concrete strength, comprising: