JP3438522B2 - Medium size for hole forming of concrete block - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium-sized die for forming holes in a concrete block, and more specifically, it forms a hole in a concrete block under the condition of expansion and expansion of the rubber expansion tube, and then forms it by reducing the diameter of the rubber expansion tube. The present invention relates to a hole forming medium mold that can be extracted from the formed hole.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a plurality of concrete blocks 200 each having a U-shaped cross section are arranged, and a tightening material such as a long wire is passed through holes 202 formed in each concrete block 200. It is practiced to form a side groove and the like by fastening. Therefore, when these concrete blocks 200 having a U-shape are poured into a mold to cast concrete in a fluid state, the holes 202 are simultaneously formed. In addition to this, it is often necessary to simultaneously form holes in the concrete block.

As a method of forming the holes 202 in such a concrete block 200, a concrete forming space 2 formed by a form 204 as shown in FIG.
The rod-shaped hole forming middle die 208 is inserted and held in the hole 06 (in the figure, the frame 204 is oriented vertically and the hole forming middle die 208 is formed).
Is vertically inserted and held, but in general, the mold is set to be horizontal and the hole forming medium mold 208 is inserted and held horizontally. In that state, the concrete in a fluid state in the mold 204 is held. After that, the hole forming middle die 208 is extracted and the hole 202 is formed therein.

FIG. 8 shows a conventionally known hole forming medium die used for this purpose. 21 in the figure
Reference numeral 0 denotes a rubber expansion tube in the hole-forming medium mold 208,
Reference numeral 212 denotes a core body provided inside thereof. Core 212
Is made up of a first metal pipe 216 and a second metal pipe 214, which are in contact with the inner surface of the rubber expansion tube 210 when not expanded. One first metal pipe 21
6 has its end (right end in the figure) fixed to an end fitting 218 that closes the end of the rubber expansion tube 210, and is integral with this, that is, the right end of the rubber expansion tube 210 in the figure. It is designed to move in the direction (axial direction).

Similarly, the second metal pipe 214 also has the left end in the figure integrated with the mouth metal fitting 221 of the end metal fitting 219, that is, the left metal end 221 of the rubber expansion tube 210. It is designed to move together in the axial direction.
The one end fitting 219 is composed of a mouth fitting 221 and a coupler 220 screwed to the fitting 221.

The free ends of the first metal pipe 216 and the second metal pipe 214 are slidably overlapped with each other over a predetermined axial length, and the rubber expansion pipe 210 expands and contracts. These first metal pipe 2
16 and the second metal pipe 214 can be slid relative to each other on the free end side.
Numeral 222 indicates that the end of the rubber expansion tube 210 is attached to each end fitting 21.
It is a fastening band for fixing to 8, 219.

The hole forming medium die 208 is used as follows. That is, with the hole forming medium mold 208 set in the concrete forming space of the mold, the supply port 224
A fluid, for example, air is introduced into the rubber expansion tube 210 to expand and expand the diameter of the rubber expansion tube 210. In this state, concrete in a fluid state is poured into the molding space 206 inside the mold 204 and solidified. Then, when the concrete is solidified, the air pressure inside is released to reduce the diameter of the rubber expansion tube 210, and the hole forming middle die 208 is formed through the formed hole.
Pull out.

In the hole forming middle die 208, the core body 212 made of a metal pipe provided inside the rubber expansion tube 210 holds the shape of the hole forming middle die 208, and the core body 212 is placed in the mold 204. This is for improving the insertability and detachability when it is inserted or removed, and at the same time, prevents the rubber expansion tube 210 from being curved when the concrete block is formed, and the hole 202 formed by this to have a bent shape. It is for doing.

[0009]

The hole forming middle die 20.
In the case of No. 8, the degree of expansion / expansion of the rubber expansion tube 210 can be changed by adjusting the air pressure introduced into the inside, so that the holes 202 having different inner diameters can be formed by the same hole forming middle die 208. Have advantages.

On the other hand, however, the hole forming middle die 20
In the case of No. 8, in order to expand the rubber expansion tube 208 to the set constant thickness, the air of a constant pressure is surely applied.
It must be introduced into the interior of the container 10, and the constant air pressure must be maintained until the cast concrete solidifies.

However, in reality, it is unavoidable that the air pressure fluctuates at the construction site, and in this case, the outer diameter of the rubber expansion tube 210 fluctuates due to the fluctuation of the air pressure, and the obtained hole 202 is obtained. There will be variations in the inner diameter of the.

Even when the rubber expansion tube 210 can be expanded to a constant thickness with an appropriate air pressure when setting the hole forming medium die 208, the heat generated when the cast concrete solidifies causes the internal There is a problem that the air expands and the air pressure increases accordingly, and the rubber expansion tube 210 is further expanded and deformed as shown by the two-dot chain line in the figure.

[0013]

[Means for Solving the Problem] The hole forming medium die of the present invention has been devised in order to solve such a problem. Thus, the hole-forming medium mold according to claim 1 comprises a rubber expansion tube and a supply port for a fluid for pressurization, and the rubber expansion tube expands and expands in diameter by the pressure of the fluid introduced through the supply port.
In a concrete block hole-forming medium mold that is capable of forming a hole of a size corresponding to the expanded diameter in a concrete block, and that can be removed from the hole by reducing the diameter of the rubber expansion tube due to pressure release, the expansion of the rubber expansion tube -It is characterized in that it is provided with a stopper means that regulates a contraction dimension in the lengthwise direction due to the diameter expansion to a preset dimension.

According to a second aspect of the present invention, there is provided the hole forming middle die according to the first aspect, wherein a rigid elongated first stopper member is inserted inside the rubber expansion tube, and one end side in the longitudinal direction thereof is located at one end side of the rubber expansion tube. The first stopper member is fixed so as to move in the longitudinal direction integrally with the one end of the rubber expansion tube, and is separated from the contacted portion of the first stopper member in the longitudinal direction by a set dimension. A second stopper member having a contact portion facing each other is fixed to the other end side of the rubber expansion tube, and the stopper means is constituted by the first stopper member and the second stopper member. It is characterized in that the contraction size of the rubber expansion tube is defined by direct or indirect contact between the portion and the contacted portion.

The hole forming medium die of claim 3 is the same as that of claim 1 or 2.
In any one of the above, the second stopper member is an end fitting attached to the other end side of the rubber expansion tube, and the tip of the first stopper member is the contacted portion. And

The hole forming medium die according to claim 4 is characterized in that
In any one of the above, the second stopper member is a rigid and elongated member inserted inside the rubber expansion tube, and the second stopper member moves integrally to the other end side of the rubber expansion tube. It is characterized by being fixed in the state.

According to a fifth aspect of the present invention, there is provided the hole forming medium die according to the fourth aspect, wherein the first stopper member and the second stopper member are
The rigid pipe has a thickness that is substantially in contact with the inner surface of the rubber expansion pipe when it is not expanded, and the first stopper member and the second stopper member are superposed so as to be slidable in the axial direction at their free ends. It is characterized by

According to a sixth aspect of the present invention, there is provided a hole forming medium die according to the fifth aspect, wherein one of the first stopper member and the second stopper member has a stepped portion, and the other has a contact portion to the stepped portion. The abutted portion is formed by the stepped portion or the contact portion on the side of the first stopper member, and the contact portion is formed by the contact portion or the stepped portion on the side of the second stopper member. It is characterized by being

The intermediate mold for hole forming according to claim 7 is characterized in that:
In any one of the above, at least one of the first stopper member and the second stopper member is detachably attached to the end fitting of the rubber expansion tube.

An intermediate die for molding a hole according to claim 8 is the intermediate die according to claim 7, wherein the end fitting includes a removable end cap for closing one end of the rubber expansion tube in a longitudinal direction, and The first stopper member or the second stopper member is detachably screwed to the end cap.

[0021]

In order to solve the above problems, the present inventor has noticed that the rubber expansion tube contracts in the length direction (axial direction) at the time of expansion / expansion of the rubber expansion tube, and the contraction size thereof. Whether or not it is possible to control the expansion and diameter expansion of the rubber expansion tube by specifying

As a result, it has been found that the expansion / expansion degree of the rubber expansion tube can be controlled by defining the lengthwise contraction dimension of the rubber expansion tube. The present invention has been made based on such knowledge.

Thus, the hole-forming middle die according to the first aspect of the present invention is provided with a stopper means for defining the shrinkage dimension in the lengthwise direction due to the expansion / expansion of the rubber expansion tube to a preset dimension. According to this, it is possible to reliably set the expansion / diameter expansion dimension of the rubber expansion tube regardless of the fluctuation of the pressure of the fluid introduced therein. Further, in the case of this hole forming medium die, there is no possibility that the diameter of the concrete expanded by the rubber expansion tube is further expanded and deformed due to the heat generated when the concrete is solidified. Therefore, according to the hole forming medium die of the present invention, It is possible to form a hole of a desired size with high accuracy and without variation.

In the present invention, a rigid and elongated first stopper member is inserted into the rubber expansion tube to fix one end thereof to one end of the rubber expansion tube, and a second stopper member is provided on the other end side of the rubber expansion tube. The stopper member can be fixed, and the contraction dimension of the rubber expansion tube can be defined by the contact between the first stopper member and the second stopper member (claim 2).

In this way, the stopper means can be easily constructed without adversely affecting the moldability of the hole by the rubber expansion tube, and when the rubber expansion tube contracts in the set length direction, It is possible to reliably prevent further shrinkage, and thereby prevent the diameter from expanding beyond the set value.

In the present invention, an end fitting attached to the end of the rubber expansion tube may be the second stopper member, and the tip of the first stopper member may be the contacted portion ( Claim 3).

That is, the contraction dimension in the lengthwise direction can be defined by bringing the tip of the rigid first stopper member into contact with the metal fitting at the end of the rubber expansion tube. With this configuration, the end fitting can also serve as the stopper member, and the required number of members can be reduced.

On the other hand, in the present invention, a pair of rigid and elongated members are inserted and arranged inside the rubber expansion tube to form a first stopper member and a second stopper member,
It is also possible to define the axial contraction dimension of the rubber expansion tube based on the abutting action of the first stopper member and the second stopper member (claim 4). Even in this case, the contraction dimension in the length direction of the rubber expansion tube can be reliably regulated to a constant dimension.

According to a fifth aspect of the present invention, in the hole forming medium die, the first stopper member and the second stopper member are constituted by a rigid pipe having a thickness which is substantially in contact with the inner surface of the rubber expansion tube when not expanded.
In addition, in the case of the hole-forming medium die according to the present invention, the shape of the rubber expansion pipe is formed by the pair of rigid pipes, which are overlapped so as to be slidable in the length direction (axial direction) at the free end portion. It can be used as a core body for holding and preventing bending, and for improving the insertability when inserting into and removing from the mold.

According to a sixth aspect of the present invention, there is provided a hole forming medium die in which one of the first stopper member and the second stopper member of the fifth aspect has a stepped portion and the other has a contact portion to the stepped portion. Then, the stepped portion or the contact portion on the first stopper member side constitutes the contacted portion, and the contact portion or the stepped portion on the second stopper member side constitutes the contact portion. By doing so, while making the first stopper member and the second stopper member to have a thickness that is substantially in contact with the inner surface of the rubber expansion tube, and stacking the free end side slidably,
The length can be regulated by abutting them at a fixed position in the length direction.

According to a seventh aspect of the present invention, there is provided a hole forming medium die in which at least one of the first stopper member and the second stopper member is detachably attached to the end fitting of the rubber expansion tube. By replacing the first stopper member or the second stopper member with one having a different axial length, the stopper position in the length direction when the rubber expansion tube is expanded / expanded can be made different. That is, it is possible to form holes having different thicknesses (inner diameters) in the concrete block by changing the stopper member while using the same hole forming medium die.

In the hole forming medium die according to claim 8, the end fitting is
A structure in which a removable end cap for closing the axial end of the rubber expansion tube is included, and a first stopper member or a second stopper member is detachably screwed to the end cap. With this configuration, by removing the end cap, the first stopper member or the second stopper member detachably attached to the end cap can be easily replaced with another member having a different length.

[0033]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 1, reference numeral 10 is a hole-forming medium mold of the present embodiment, and 12 is a rubber expansion tube. The rubber expansion tube 12
The outer rubber layer 14, the fiber reinforcing layer 16, and the inner rubber layer 18
It has a laminated structure with. Here, the fiber reinforcing layer 16 is a braided fiber having a knitting angle of less than a static angle (54 °) (for example, about 30 °) so that the rubber expansion tube 12 can be sufficiently expanded / expanded. .

Reference numeral 20 denotes an end fitting, which is a metal sleeve 2.
4 is fixed to the end of the rubber expansion tube 12. The end fitting 20 is configured to close the end of the rubber expansion tube 12.

Reference numeral 22 denotes the other end fitting fixed to the end on the opposite side of the rubber expansion tube 12, and this end fitting 22
Is composed of a cylindrical mouth metal fitting 26 and a coupler 28 screwed thereto. This end fitting 22 is also
It is fixed to the end of the rubber expansion tube 12 together with the metal sleeve 29.

Reference numerals 30 and 32 are a first stopper member and a second stopper member, respectively, which are an end fitting 20 and a mouth fitting 26, respectively.
Is formed integrally with. These first stopper members 30
The second stopper member 32 is made of a metal pipe having a thickness that substantially contacts the inner surface of the rubber expansion tube 12 when it is not expanded, as shown in FIG. 1 (B).

That is, in the present embodiment, the first stopper member 30 and the second stopper member 32 retain the shape of the rubber expansion tube 12 as a whole to prevent bending, and also have the insertability of the rubber expansion tube 12 at the time of insertion into and removal from the mold. Also serves as a core to keep it in good condition.

The first stopper member 30 has a small-diameter portion 34 on the side opposite to the end fitting 20, and the stepped portion formed at the base portion thereof serves as the contacted portion 36. On the other hand, the second stopper member 32 has a straight tube shape with a uniform thickness, and its tip is set in the length direction with respect to the stepped shaped contacted portion 36 when the rubber expansion tube 12 is not expanded. The contact portions 38 are opposed to each other with a dimension a.

In the hole-forming middle mold 10 of this embodiment, air pressure is introduced into the inside of the mold 10 from the supply port 40, and the rubber expansion pipe 12 is expanded and expanded by the air pressure. To be At this time, the length of the rubber expansion tube 12 is shortened as the rubber expansion tube 12 expands and expands in the radial direction. At that time, the first stopper member 3 fixed to each end of the rubber expansion tube 12
0 and the second stopper member 32 move in the length direction integrally with the respective end portions, and when the rubber expansion tube 12 contracts in the same direction by a as a whole, the contacted portion of the first stopper member 30. 36 and the contact portion 38 of the second stopper member 32 are in contact with each other in the lengthwise direction, and further contraction of the rubber expansion tube 12 in the lengthwise direction is prevented.

That is, in the case of the hole forming medium die 10 of the present embodiment, the maximum expansion dimension of the rubber expansion tube 12 is set to the first stopper by introducing the air pressure into the rubber expansion tube 12 with a sufficient pressure. The outer diameter D ₁ at the time when the contacted portion 36 of the member 30 and the contacting portion 38 of the second stopper member 32 contact each other can be set.

In this manner, with the rubber expansion tube 12 expanded and expanded in diameter, concrete in a fluidized state is placed in a mold (not shown), and the concrete placed while maintaining that state is placed. Let it solidify. Then, when the concrete hardens, the internal air pressure is released to reduce the diameter of the rubber expansion tube 12, and subsequently this is extracted from the mold. Here, in the concrete block molded by the formwork,
A hole having the same inner diameter dimension as the maximum expansion dimension D ₁ of the rubber expansion tube 12 is formed.

As described above, the hole forming middle die 10 of this embodiment is
By adjusting the contraction dimension in the length direction of the rubber expansion tube 12 to a preset dimension, the expansion / diameter expansion dimension of the rubber expansion tube 12 is controlled. According to this example,
It is possible to reliably set the expansion / diameter expansion dimension of the rubber expansion tube 12 regardless of the fluctuation of the pressure of the air introduced into the inside.

Further, in the hole forming medium die 10, the rubber expansion tube 12 does not expand and deform further than the time of setting due to the heat generated when the cast concrete is solidified, so that the hole of the required size is formed. It can be molded with high accuracy and without variations.

Further, in this example, the contraction dimension of the rubber expansion tube 12 is defined by the contact between the first stopper member 30 and the second stopper member 32 inserted inside the rubber expansion tube 12. The stopper means can be easily configured without adversely affecting the moldability of the hole by the rubber expansion tube 12, and when the rubber expansion tube 12 contracts in the set dimension length direction, surely further contraction is achieved. Can be stopped.

By the way, FIG. 5 and Table 1 show that a hole-forming medium mold 10 having an initial length L of 2125 mm and an outer diameter of 30.2 mm when the rubber expansion tube 12 is not expanded is used. Is introduced at various pressures to measure the outer diameter dimension and the length dimension. In this example, the fiber reinforcement layer 16 has a knitting angle of 31 ° and an a dimension of 17
It is a result when it is set to 5 mm.

[0046]

[Table 1]

As is apparent from these results, in the case of the product of this embodiment, the expansion / expansion of the rubber expansion tube 12 is stopped at some point when the air pressure is increased, and the outer diameter dimension is maintained at a constant dimension. I understand that it will be done.

Unlike the above example, as shown in FIG. 2, the end fitting 42 on the closed side with respect to the rubber expansion tube 12 is
It is also possible to use a cylindrical fitting 44 and a metal end cap 46 that closes the opening.

FIG. 3 shows another embodiment of the present invention. In this example, the first stopper member 48 is constituted by a metal pipe integrated with the end fitting 20, while the end fitting 22 on the opposite side is formed. The second stopper member is constituted by the mouth metal fitting 52 in, and the tip of the first stopper member 48 is attached to the contacted portion 50.
On the other hand, the inner end of the second stopper member composed of the mouth metal fitting 52 serves as the contact portion 54.

Here, the first stopper member 48 made of a metal pipe has a uniform thickness in the length direction,
Further, as shown in (B), the rubber expansion tube 12 has such a thickness that it is almost in contact with the inner surface thereof when the rubber expansion tube 12 is not expanded. That is, in this example, the first stopper member 48 also serves as a core body that holds the rubber expansion tube 12 in a straight shape.

As shown in (B), the tip of the first stopper member 48, that is, the inner end of the second stopper member composed of the contacted portion 50 and the fitting 52, is not connected to the rubber expansion tube 12. At the time of expansion, they are opposed to each other in the axial direction with a set dimension a therebetween.

Also in the hole forming medium die 56 of this example, when the rubber expansion tube 12 expands and expands in diameter by the introduction of air pressure,
The abutted portion 50 of the first stopper member 48 and the abutted portion 54 of the second stopper member composed of the mouth metal fitting 52 abut in the lengthwise direction, and the rubber expansion tube 12 has a constant outer diameter dimension (D ₁ ). It is prevented from expanding and deforming as described above. That is, the rubber expansion tube 12 is surely expanded and deformed to the dimension D ₁ by the introduction of the air pressure.

Therefore, even when the hole forming medium die 56 of this example is used, holes having a predetermined size (D ₁ ) can be surely formed at the same time with high accuracy when forming a concrete block. In this example, since the end fitting 22 also serves as the second stopper member, there is an advantage that the number of necessary members is reduced.

FIG. 4 shows still another embodiment of the present invention. The hole forming middle die 58 of this embodiment has one end fitting 4
2 is composed of a cylindrical mouth metal fitting 44 and a metal end cap 60 that is screwed into the metal fitting 44 to close the opening, and a rod-shaped first stopper member 62 is attached to the end cap 60. In this case, the end cap 60 is used to hold it.

Here, the first stopper member 62 forms a relatively large gap between itself and the inner surface of the rubber expansion tube 12 when the rubber expansion tube 12 is not expanded, as shown in FIG. It consists of The length is set such that the contacted portion 50 at the tip and the contacting portion 54 formed of the inner end of the second stopper member formed of the mouth metal fitting 52 are axially opposed to each other with a set dimension b. There is. Reference numeral 64 is a lock nut for preventing the first stopper member 62 from loosening.

In the case of the hole forming medium die 58 of this example, by removing the end cap 60, the first stopper member 62 screwed to the end cap 60 can be replaced with another first stopper member 62 having a different length. And by this the dimension b
Can be changed freely.

That is, in the case of the hole forming medium die 58 of this example, the maximum diameter expansion dimension D ₁ when the rubber expansion tube 12 is expanded and expanded corresponds to the axial length of the first stopper member 62 of various lengths. It can be adjusted to the specified dimensions.

That is, according to the hole forming middle die 58 of the present embodiment, by replacing the first stopper member 62 with another member having a different length, a stopper in the lengthwise direction when the rubber expansion tube 12 is expanded / expanded. The positions can be made different, and it becomes possible to form holes having different thicknesses (inner diameters) in the concrete block by changing the first stopper member 62 while using the same hole forming medium die 58.

The embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention can be configured in a form in which various modifications are made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a view showing a hole forming medium die which is an embodiment of the present invention.

FIG. 2 is a view showing a hole forming medium die according to another embodiment of the present invention.

FIG. 3 is a view showing a hole forming medium die which is still another embodiment of the present invention.

FIG. 4 is a view showing a hole forming medium die which is still another embodiment of the present invention.

FIG. 5 is a diagram showing the results of a test conducted to confirm the effect of the hole forming medium die of FIG. 1.

FIG. 6 is an explanatory diagram showing an example of forming a hole in a concrete block.

FIG. 7 is a diagram showing a part of a forming process of the concrete block of FIG.

FIG. 8 is a diagram showing in detail an example of a conventional hole-forming medium die of FIG.

[Explanation of symbols]

10,56,58 Hole Molding Medium 12 rubber expansion tube 20,22,42 End fitting 26,44 mouth metal fittings 30, 48, 62 First stopper member 32 Second stopper member 36,50 Contacted part 38, 54 abutment part 40 supply port 46,60 End cap 52 Mouthpiece (second stopper member)

Claims (8)

(57) [Claims] 1. A rubber expansion tube and a supply port for a pressurizing fluid are provided, and the rubber expansion tube expands and expands in diameter by the pressure of the fluid introduced through the supply port, and has a size corresponding to the expanded diameter. In a hole forming medium die of a concrete block that can be removed from the hole by forming a hole in the concrete block and reducing the diameter of the rubber expansion tube by releasing pressure, in the length direction along with the expansion and expansion of the rubber expansion tube. An intermediate mold for forming holes in a concrete block, which is provided with stopper means for defining a shrinkage dimension to a preset dimension. 2. The rubber expansion tube according to claim 1, wherein a rigid longitudinal first stopper member is inserted into the rubber expansion tube, and one longitudinal end thereof is fixed to one end side of the rubber expansion tube. Is configured to move in the longitudinal direction integrally with the one end of the rubber expansion tube, and includes an abutting portion facing the abutted portion of the first stopper member with a set distance in the longitudinal direction. A second stopper member is fixed to the other end of the rubber expansion tube, and the stopper means is constituted by the first stopper member and the second stopper member. A middle die for forming a hole in a concrete block, characterized in that the contraction dimension of the rubber expansion tube is defined by direct or indirect contact. 3. The second stopper member according to claim 1, wherein the second stopper member is an end fitting attached to the other end side of the rubber expansion tube, and the tip of the first stopper member is the covered member. Medium-sized mold for forming holes in a concrete block, characterized by being a contact portion. 4. The rubber stopper according to claim 2, wherein the second stopper member is a rigid and elongated member inserted inside the rubber expansion tube, and the second stopper member is the rubber expansion member. A medium-sized die for forming a hole in a concrete block, which is fixed to the other end of the pipe while being integrally moved. 5. The first stopper member and the second stopper member according to claim 4, wherein the first stopper member and the second stopper member are made of a rigid pipe having a thickness that is substantially in contact with an inner surface of the rubber expansion pipe when the rubber pipe is not expanded. A middle block hole forming mold for a concrete block, wherein the stopper member and the second stopper member are superposed on each other at a free end thereof so as to be slidable in the axial direction. 6. The first stopper member and the second stopper member according to claim 5, wherein one of the first stopper member and the second stopper member is formed with a stepped portion, and the other is formed with a contact portion to the stepped portion. A concrete block characterized in that the abutted portion is constituted by a stepped portion or a contact portion on the member side, and the abutting portion is constituted by a contact portion or a stepped portion on the second stopper member side, respectively. Medium size for hole forming. 7. The method according to claim 2, wherein at least one of the first stopper member and the second stopper member is detachably attached to an end fitting of the rubber expansion tube. Medium size for forming holes in the characteristic concrete block. 8. The end fitting according to claim 7, wherein the end fitting includes a removable end cap that closes either end of the rubber expansion tube in the longitudinal direction, and the end cap is provided with the first end cap. A medium-sized die for forming a hole in a concrete block, wherein one stopper member or a second stopper member is detachably screwed.