JP2005288527A - Insert casting cap nut, and casting method using insert casting cap nut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert casting cap nut and a casting method using the insert casting cap nut by which the improvement of productivity of the castings and the reduction of producing cost can sufficiently be attained. <P>SOLUTION: In the insert casting cap nut 10, which is provided with an outer peripheral surface to be insert-cast with casting material of the casting and an exposure surface 11a to be exposed from the casting material so as to face an insertion hole 12 in a cylindrical cap nut main body 11 having the insertion hole 12, tapered surfaces 13a, 13b widening toward the exposure surface 11a side are formed on the outer peripheral surface of the cap nut main body 11, and a fall-out preventive means capable of holding the cap nut 11 to the casting material is provided on the tapered surfaces 13a, 13b. The cap nut main body 11 can be attached to/detached from a sand mold pattern 19 for forming the sand mold 22 being the mold through the tapered surface 13a, 13b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting cap nut and a casting method using the casting cap nut, and more particularly to a casting cap nut that can be attached to a sand mold model and a casting method using the casting cap nut. About.

In general, when a member or the like is assembled to a large or heavy cast product using a fastening bolt, the cast product is often cast by casting a cap nut with a casting material.
For example, Patent Document 1 discloses a casting method in which a cap nut is cast by a full mold method using a disappearance model.
The insertion hole provided in this cap nut has a stepped shape composed of a small-diameter hole on the bottom side and a large-diameter hole on the opening side, and a V-shaped ring is formed on the outer periphery of the cap nut corresponding to the large-diameter hole Notches are provided.
Then, with the annular notch as a boundary, the bottom side portion of the cap nut serves as the cap nut body, and the opening side portion serves as the extension tube portion.

In this casting method using a cap nut, a cap nut into which a fixing bolt is screwed is inserted into the support hole provided in the vanishing model, the cap nut is inserted into the support hole, and a sand mold is formed so as to surround the vanishing model. To mold.
Next, the casting material is poured into a sand mold so that the casting material replaces the disappearance model, and the cap nut is cast into the casting material.
In the cast product taken out from the sand mold after cooling, by hitting the head of the fixing bolt, the extension cylinder is sheared and removed from the V-shaped annular notch as a starting point, and the shear surface facing the insertion hole is It becomes almost the same surface as the surface of the casting part.

On the other hand, FIGS. 5 and 6 show a casting method in which the cap nut 40 is cast using a resin sand mold 49 instead of the disappearance model.
The sand mold model 49 used here is a mold for forming a sand mold 50 as a mold, and the sand mold model 49 is provided with a recess 49a corresponding to the position where the cap nut 40 is cast.
The inner diameter surface of the recess 49a has a tapered shape that widens from the back toward the surface.
A mounting mold 45 that can be mounted in the concave portion 49a of the sand mold model 49 is prepared. The mounting mold 45 has a bolt hole 46 into which a fixing bolt 47 as a fixing member can be screwed.
Since the outer diameter surface of the mounting die 45 follows the tapered inner surface of the concave portion 49a, the mounting die 45 has a substantially truncated cone shape, and the mounting die 45 can be easily attached to and detached from the concave portion 49a. It has become something that can be done.

The cap nut 40 used here has a substantially cylindrical shape, and a bottomed screw hole 42 that allows the fixing bolt 47 to be screwed is formed in the exposed surface 41a in the longitudinal direction.
Further, when the cap nut 40 is cast with a casting material, a locking groove 43 is formed on the side surface as a retaining member for the casting material, and the inclined portion 44 is used as a detent for the casting material. It has.

The procedure of this casting method will be described. First, a lock nut 48 is screwed onto the fixing bolt 47.
Next, the mounting die 45 into which the fixing bolt 47 is screwed is mounted in the concave portion 49 a provided in the sand mold model 49, and the mounting die 45 is held by the sand mold model 49.
Thereafter, the sand mold 50 is formed by filling the casting sand so as to surround the sand mold model 49, and a part of the fixing bolt 47 is embedded in the sand mold 50 as shown in FIG. .
Next, the sand mold model 49 is removed from the sand mold after the foundry sand has hardened. However, since the fixing bolt 47 is embedded in the sand mold 50, the mounting mold 45 is moved to the sand mold 50 side when the sand mold model 49 is removed. stay.
Next, as shown in FIG. 5B, the mounting die 45 is removed from the fixing bolt 47, and as shown in FIG. 5C, the tip of the fixing bolt 47 protruding from the surface of the sand die 50 is applied. Then, the cap nut 40 to be cast is screwed.
At this time, the exposed surface 41 a of the cap nut 40 is in contact with the sand mold 50, and the cap nut 40 is held by the fixing bolt 47.

Next, the casting material is poured into the sand mold 50. Since the casting material spreads through the sand mold 50, the casting material is held in the sand mold 50 by the fixing bolts 47 as shown in FIG. The cap nut 40 is cast into the casting material.
As shown in FIG. 6B, the cast product 51 taken out from the sand mold 50 after cooling the cast material includes a cast part 52 made of the cast material and a cap nut 40 cast into the cast part 52. 40 is still screwed with a fixing bolt 47.
Then, by removing the fixing bolt 47 from the cap nut 40, as shown in FIG. 6C, a cast product 51 in which the cap nut 40 is cast is obtained.
JP 2002-192326 A (page 2-4, FIG. 1 to FIG. 2)

However, the cap nut disclosed in Patent Document 1 has a problem that the object of application is limited to the full mold method using the disappearance model, and is not applicable to the casting method using the resin sand mold model.
5 and 6, after the sand mold is formed and the sand mold model is removed from the sand mold, the mounting mold mounted in the concave portion of the sand mold model is removed from the fixing bolt, Replacement work of attaching nuts to fixing bolts must be carried out, and such replacement work is a laborious work requiring manpower, and it is not possible to sufficiently improve the productivity of casting products and reduce manufacturing costs. There is a problem.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a cast-in bag nut and a cast-in bag that can sufficiently improve the productivity of a cast product and reduce the manufacturing cost. The present invention provides a casting method using a nut.

  In order to achieve the above-mentioned object, the invention according to claim 1 is a method in which a cylindrical cap nut body having an insertion hole is cast so as to face the outer peripheral surface cast by the casting material of the cast product and the insertion hole. A cap nut having an exposed surface exposed from the material, and a tapered surface extending toward the exposed surface is formed on the outer peripheral surface of the cap nut body, and Retaining means for holding the cap nut body is provided on the tapered surface, and the cap nut body is detachable from the sand mold model forming a sand mold as a mold via the tapered surface. It is characterized by.

  According to the first aspect of the present invention, since the cast-in cap nut is detachable from the sand mold model and can be held against the casting material, the cast-in bag is fixed to the fixing member. It is possible to perform a series of castings with the nuts screwed in and attached to the sand mold model, and there is no need to prepare the mounting mold and the cap nut separately as in the prior art. There is no need to perform complicated replacement work with the nut.

  According to a second aspect of the present invention, in the cast-in cap nut according to the first aspect, the insertion hole allows a fastening bolt to be screwed in or a fixing member supported to the sand mold to be freely inserted. It is characterized by.

  According to the invention described in claim 2, in addition to being able to hold the cap nut for casting into the sand mold through the fixing member inserted into the insertion hole, On the other hand, a fastening bolt can be screwed and a member or the like can be attached.

  According to a third aspect of the present invention, in the cast-in cap nut according to the first or second aspect, a vertical surface is formed between the tapered surface and the exposed surface.

  According to the invention described in claim 3, at the time of manufacturing the cap nut for casting, the vertical surface formed between the tapered surface and the exposed surface is gripped by a processing device such as a lathe, so that the bag for casting can be obtained. The taper surface of the nut can be easily processed.

  According to a fourth aspect of the present invention, in the cast-in cap nut according to the second or third aspect, the insertion hole includes a large-diameter hole on the opening side and a small-diameter hole on the bottom side that is threaded. The large-diameter hole allows the fixing member to be inserted, and the small-diameter hole allows the fastening bolt to be inserted.

According to the fourth aspect of the present invention, during casting, the fixing member is inserted into the large-diameter hole on the opening side of the insertion hole, and the casting material is prevented from entering the small-diameter hole on the screwed bottom side.
In addition, the fixing member inserted into the large-diameter hole of the insertion hole is supported in the sand mold during casting, and a cast part for casting the cap nut for casting is formed by the cast material poured, and fixed after casting. The workpiece is removed from the cast cap nut.
By removing the fixing member from the cap nut for casting, a cast product in which the cap nut for casting is cast is obtained.

  The invention according to claim 5 is a cylindrical cap nut body having an insertion hole, an outer peripheral surface cast by a casting material of a cast product, and an exposed surface exposed from the casting material so as to face the insertion hole. A taper surface that widens toward the exposed surface is formed on an outer peripheral surface of the bag nut body, and the bag is formed against the casting material. A retaining means for holding the nut body is provided on the taper surface, and the cap nut body is detachable from the sand mold model forming a sand mold as a mold through the taper surface. A cap nut, a fixing member is inserted into the cap nut, the cap nut is attached to the sand mold model, the sand mold is filled with foundry sand, and the sand mold is Forming the sand mold model from the sand mold. At the same time, the cap member is supported by the sand mold by the fixing member, and the outer peripheral surface of the cap nut is cast into the casting material by pouring the casting material into the sand mold. It is characterized by that.

  According to the fifth aspect of the present invention, since the cast-in cap nut is detachable from the sand mold model and can be held against the casting material, the cast-in bag is fixed to the fixing member. It is possible to perform a series of castings with the nuts screwed in and attached to the sand mold model, and there is no need to prepare the mounting mold and the cap nut separately as in the prior art. There is no need to perform complicated replacement work with the nut.

  According to the present invention, it is possible to sufficiently improve the productivity of the cast product and reduce the manufacturing cost.

Hereinafter, a casting method using the cast-in cap nut and the cast-in cap nut according to the embodiment of the present invention will be described with reference to FIGS.
First, a cast-in cap nut (hereinafter simply referred to as “cap nut”) 10 will be described.
As shown in FIG. 1, the cap nut body 11 of the cap nut 10 has a substantially cylindrical shape, and a bottom surface in which the bottomed insertion hole 12 is the other end surface on the exposed surface 11 a that is one end surface. It is drilled toward 11b.
A female screw 12a is formed in the insertion hole 12, and a fastening bolt (not shown) for attaching a member can be screwed into a cast product 23 after casting, which will be described later. A fixing bolt 17 as a working member can be screwed.
Since the exposed surface 11a of the cap nut body 11 has a larger diameter than the bottom surface 11b, the side surfaces of the cap nut body 11 are formed with tapered surfaces 13 (13a, 13b) that widen toward the exposed surface 11a from the bottom surface 11b. The
In this embodiment, a vertical surface 14 is formed between the exposed surface 11 b and the tapered surface 13 to be gripped by a processing device such as a lathe when the cap nut 10 is manufactured.

Two tapered locking grooves 15 parallel to each other are formed on the tapered surface 13 of the cap nut body 11, and these locking grooves 15 prevent the cap nut 10 from dropping from the casting portion 24 in the casting 23. It is a retaining means for sure prevention.
Moreover, the planar inclined part 16 which inclines toward the taper surface 13b from the bottom face 11b of the cap nut main body 11 is formed, and this prevents the cap nut 10 from rotating with respect to the casting part 24 in the casting 23. It is a detent means for doing.
The cap nut 10 according to this embodiment is formed of an iron-based metal material (SC material), and is cast by a casting portion 24 in a cast product 23 described later, except for the exposed surface 11a.

  On the other hand, the fixing bolt 17 as the fixing member and the lock nut 18 as the covering material are well-known bolts and nuts, and the fixing bolt 17 has a male screw corresponding to the insertion hole 12 in the cap nut 10. The lock nut 18 is provided in the shaft portion 17b and has a screw hole 18a corresponding to the male screw of the fixing bolt.

Next, the casting method of this embodiment will be described with reference to FIGS. 2 and 3. As shown in FIG. 2 (a), first, the casting method is a mold so that the casting material can be poured. A sand mold 22 is formed.
In order to obtain the sand mold 22, a sand mold model 19 is used. The sand mold model 19 has a recess 20.
The recess 20 includes a side wall surface 20a that substantially corresponds to the tapered surface 13 of the cap nut 10 so that the cap nut 10 can be attached thereto.
Further, a magnet 21 as a magnetic body is embedded near the bottom surface of the concave portion 20, and the attractive force of the magnet 21 acts on the cap nut main body 11 so that the cap nut 10 attached to the concave portion 20 easily falls off. It is planned not to be.
In this embodiment, the magnet 21 is used, but an adhesive tape or an adhesive may be used instead of the magnet 21.

Prior to forming the sand mold 22, as shown in FIG. 2A, a lock nut 18 as a covering member is screwed into the fixing bolt 17, and the distal end side of the shaft portion 17 b of the fixing bolt 17 is locked. Project from the nut 18.
Next, the protruding shaft portion 17 b of the fixing bolt 17 is screwed into the insertion hole 12 of the cap nut 10, and the exposed surface 11 a of the cap nut 10 and the back surface of the lock nut 18 are brought into close contact with each other.
Since a part of the exposed surface 11 b is in close contact with the back surface of the lock nut 18, even if the cap nut 10 is shallowly screwed to the fixing bolt 17, the bag is fixed to the fixing bolt 17. The nut 10 is securely held.
Then, the cap nut 10 including the fixing bolt 17 and the lock nut 18 is attached to the sand mold model 19. In this embodiment, the surface of the sand mold model 19 and the exposed surface 11 b of the cap nut 10 are flush with each other. Is set to

After the cap nut 10 is mounted on the sand mold model 19, casting sand for forming the sand mold 22 is filled into the sand mold model 19. As shown in FIG. A part of the shaft portion 17 b of the fixing bolt 17 provided, the head portion 17 a and the lock nut 18 are covered with casting sand and embedded in the sand mold 22.
In this embodiment, since the foundry sand containing the furan resin agent is used, the sand mold 22 formed of the foundry sand has a strong shape retaining force due to the curing of the furan resin agent.
For this reason, as shown in FIG. 2C, even if the sand mold model 19 is removed from the sand mold 22, the sand mold 22 does not collapse easily, and the cap nut 10 is fixed to the sand mold 22 with the fixing bolt 17 and It is supported via a lock nut 18.
When the sand mold model 19 is removed from the sand mold 22, the cap nut 10 attached to the sand mold model 19 is held by the sand mold model 19 by magnetic attraction, and the recess 20 is formed in the cap nut 10. In combination with the provision of the side wall surface 20a substantially corresponding to the taper surface 13, the sand mold 19 is easily separated.

Next, the molten casting material is poured into the sand mold 22.
Here, cast iron (FC material) is used as a casting material, but an aluminum-based metal material, a copper-based metal material, or the like can be used in addition to an iron-based metal material such as cast iron.
As shown in FIG. 3A, the casting material surrounds the cap nut 10 except for the exposed surface 11a of the cap nut 10 by pouring, so the cap nut 10 is cast into the casting material. It can be said that it is in a state.
When the casting material is poured, the exposed surface 11a of the cap nut 10 and the back surface of the lock nut 18 are in close contact with each other, so that the molten casting material does not enter and the insertion hole 12 of the cap nut 10 is inserted. The casting material never reaches.

When a required amount of casting material is poured into the sand mold 22, the poured casting material is cooled, and the sand mold 22 is removed after cooling, the cap nut 10 is cast as shown in FIG. 3 (b). A rare casting 23 is obtained.
The cast product 23 includes a cast part 24 formed of a cooled casting material and a cap nut 10 cast by the cast part 24. The cap nut 17 is screwed into the cap nut 10. It is in the state that was done.

Then, as shown in FIG. 3 (c), the fixing bolt 17 having the lock nut 18 is removed from the cap nut 10 to complete the cast product 23.
The removed fixing bolt 17 can be reused several times as a fixing member, and the lock nut 18 can be repeatedly used as a covering member in the same manner.
In a state where the fixing bolt 17 is removed from the cap nut 10, the exposed surface 11a and the surface of the casting portion 24 form the same surface, and the exposed surface 11a where the back surface of the lock nut 18 is in close contact is smooth. The state is maintained.
Further, the casting portion 24 is in a state in which the cap nut 10 is cast. However, since the locking groove 15 of the cap nut body 11 and the casting portion 24 are locked to each other, the cap nut 10 is dropped from the casting portion 24. In addition, the cap nut 10 is not rotated with respect to the casting portion 24 by the inclined portion 16 of the cap nut main body 11.
For example, when fixing a member or the like to the cast product 23 using a fastening bolt (not shown), a fastening bolt capable of screwing the fastening bolt into the insertion hole 12 of the cap nut 10 and do it.

According to the cap nut 10 and the casting method using the cap nut 10 according to this embodiment, the following effects can be obtained.
(1) Since the cap nut 10 is detachable from the sand mold model 19 and can be held with respect to the casting portion 24 formed of a casting material, the cap nut is attached to the fixing bolt 17. It is possible to perform a series of castings from the formation of the sand mold 22 to the removal of the fixing bolt 17 with the screw 10 inserted into the sand mold model 19, and the mounting mold and the cap nut can be separately provided as in the prior art. There is no need to prepare, and there is no need to perform complicated replacement work between the mounting die and the cap nut during casting.
(2) The cap nut 10 can be held on the sand mold 22 through the fixing bolt 17 inserted into the insertion hole 12, and the fastening bolt is screwed onto the cap nut 10 that has been cast. The member or the like can be attached to the casting 23.
(3) Since the outer periphery of the cap nut 10 is a tapered surface 13 that widens toward the exposed surface 11a from the bottom surface 11b, it can be easily removed from the sand mold model 19 after the sand mold 22 is formed. In addition, since the area of the exposed surface 11a is set larger than the bottom surface 11b and the exposed surface 11a can secure a sufficient area as a seating surface, for example, when attaching a member such as a heavy object to the cast product 23, It is possible to use a fastening bolt that works with a large axial force.

(4) Since the casting material is poured in a state where the back surface of the lock nut 18 as the covering member is in close contact with the exposed surface 11a, the casting material is difficult to enter the exposed surface 11a, and the exposed surface 11a is used for attaching the member. It can be used immediately as a seating surface.
(5) By screwing the lock nut 18 into the fixing bolt 17, the amount of insertion of the fixing bolt 17 screwed into the cap nut 10 can be adjusted on a screw thread basis. Considering the workability of shrinkage and removal of the fixing bolt 17 after casting, the fixing bolt 17 can be screwed into the cap nut 10 in an appropriate state.
(6) Since the back surface of the lock nut 18 as the covering member is in close contact with the exposed surface 11 a of the cap nut 10, the fixing bolt 17 is securely held against the cap nut 10, and the cap nut 10 is fixed to the fixing bolt 17. There is almost no inclination to it.

In this embodiment, the exposed surface 11a exposed from the surface of the casting part 24 and the surface of the casting part 24 are the same surface. For example, as shown in FIG. You may make it protrude with respect to the surface of the casting part 24. FIG.
Although not shown, the exposed surface 11a may be recessed with respect to the surface of the casting portion 24. In this case, the covering member is provided so that the cast material does not touch the male screw of the fixing bolt 17. The lock nut 18 is preferably screwed into the fixing bolt 17 so that the back surface of the lock nut 18 is in close contact with the exposed surface 11a.
In this way, by making the exposed surface 11a exposed from the surface of the casting part 24 and the surface of the casting part 24 non-coplanar, it is possible to deal with a wide range of mounting conditions for members attached to the casting 23. Is possible.

Further, in the above embodiment, the lock nut 18 as the covering member is used for the fixing bolt 17 as the fixing member to which the cap nut 10 is screwed, but as shown in FIG. In addition, when there is no loosening of the cap nut 10 with respect to the fixing bolt 17 and the cap nut 10 does not tilt with respect to the fixing bolt 17, the lock nut 18 as a covering member may not be used. .
In this case, the operation of screwing the lock nut 18 to the fixing bolt 17 can be omitted, the members necessary for casting can be reduced, and the manufacturing cost of the cast product 23 can be further reduced.

Furthermore, as another example of the cap nut 10, a cap nut 30 shown in FIG. 4C may be used.
In this cap nut 30, the insertion hole 32 of the cap nut body 31 may have a stepped shape with different diameters so that the fixing bolt 17 can be screwed into the large diameter hole 32a on the exposed surface 31a side, A fastening bolt (not shown) may be screwed into the small diameter hole 32b.
In this case, even if the large-diameter hole 32a and the fixing bolt 17 are seized by casting, the small-diameter hole 32b remains unused even after casting, so that the small-diameter hole 32b and the fixing bolt 17 are seized. The fastening bolt can be screwed into the small-diameter hole 32b in the casting 23.
Other configurations of the cap nut 30, for example, the tapered surface 33, the vertical surface 34, the locking groove 35, and the inclined portion 36 are the same as those of the cap nut 10 described above.

The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist of the invention. For example, the following modifications may be made.
In the above embodiment, the angle of the tapered surface of the cap nut is not particularly specified, but in order to remove the cap nut from the sand mold model, at least the angle with the axis of the insertion hole is 2 degrees or more. What is necessary is just to set it as about 3.5 to 40 degree | times as a more practical range.
○ In the above embodiment, locking grooves as retaining means are formed on the outer periphery of the cap nut so as to be parallel to each other. However, when attaching a member or the like to the cast product, it is screwed into the small diameter hole of the cap nut. When the fastening force of a bolt or the like to be inserted is relatively small, it is not necessary to provide a locking groove. In this case, since the processing for the cap nut is omitted, the production cost of the cast product can be reduced. Further, the number of locking grooves is not limited to two, and at least one locking groove may be provided.
In the above embodiment, the locking grooves as the retaining means are formed on the outer periphery of the cap nut so as to be parallel to each other. However, the retaining means is not limited to the locking grooves, and at least the casting portion in the cast product. Any suitable configuration may be used as long as the cap nut can be prevented from coming off. For example, an appropriate retaining means such as providing a protrusion on the outer periphery of the cap nut can be employed.

In the above embodiment, a locking groove as a retaining means is provided on the outer periphery of the cap nut, and an inclined surface as a detent means is provided independently on the bottom surface of the cap nut. A protrusion or a recess having both the rotation stop means and the rotation prevention means may be provided. In this case, the protrusion prevention means and the recess means constitute the retaining means and the rotation prevention means.
In the above embodiment, a specific use as a cast product was not shown. However, a casting method and a cast product according to the present invention are, for example, a counterweight in an industrial vehicle or a large press mold for vehicle manufacture. In such a large metal part or metal product that tends to have many mounting members, there are a large number of female screws for mounting the mounting member, and the large size makes it difficult to handle. Therefore, it is advantageous to provide a cast product capable of casting a large number of cap nuts.

Here, although not described in the claims, technical matters related to the present invention will be described just in case.
As a first technical matter, in the casting method using the cast-in cap nut according to claim 5, the cast-in cap nut is made of an iron-based material, and a magnetic material is embedded in the sand mold model. In addition, the cast-in cap nut is attached to the sand mold model by the attractive force of the magnetic body.
In this case, the work of attaching the cast-in cap nut to the sand mold model is simplified, and the working time can be shortened.

As a second technical matter, in the casting method using the cast-in bag nut according to claim 5 or 6, the fixing member to be inserted into the cast-in bag nut is provided in advance in the cast-in bag. A covering member that covers a part of the exposed surface of the nut is attached.
In this case, since the covering member covers a part of the exposed surface of the cap nut for casting, it becomes difficult for the casting material to enter the insertion hole when pouring the casting material. The seizure of the bag nut can be suppressed.

It is a top view, a side view, and a bottom view of a cap nut for casting according to an embodiment of the present invention. It is explanatory drawing which shows the process before pouring in the casting method of this embodiment. It is explanatory drawing which shows the process from pouring to a casting in the casting method of this embodiment. It is sectional drawing which shows the usage example of a cap nut for cast-in, and another example of a cast-in nut. It is explanatory drawing which shows the process until mounting | wearing with a cap nut in the conventional casting method. It is explanatory drawing which shows the process from pouring to a cast product in the conventional casting method.

Explanation of symbols

10, 30, 40 Cap nut 11a, 31a, 41a Exposed surface 12, 32 Insert hole 13, 33 Tapered surface 15, 35, 43 Locking groove 16, 36, 44 Inclined portion 17, 47 Fixing bolt 18, 48 Lock nut 19, 49 Sand mold model 20, 49a Recess 22, 50 Sand mold 23, 51 Cast product

Claims (5)

A bag for casting, in which a cylindrical bag nut body having an insertion hole is provided with an outer peripheral surface cast by a casting material of a cast product and an exposed surface exposed from the casting material so as to face the insertion hole A nut,
A tapered surface spreading toward the exposed surface side is formed on the outer peripheral surface of the cap nut body,
Retaining means that can hold the cap nut body with respect to the casting material is provided on the tapered surface,
The cap nut body is detachable from the sand mold model forming a sand mold as a mold through the tapered surface. The cast-in cap nut according to claim 1, wherein the insertion hole allows a fastening bolt to be screwed in or a fixing member supported with respect to the sand mold to be inserted. 3. A cap nut for casting according to claim 1, wherein a vertical surface is formed between the tapered surface and the exposed surface. The insertion hole has a stepped shape composed of a large-diameter hole on the opening side and a small-diameter hole on the bottom side that is threaded. The large-diameter hole allows the fixing member to be inserted, and the small-diameter hole is 4. The cap nut for casting according to claim 2, wherein the fastening bolt is freely insertable. A bag for casting, in which a cylindrical bag nut body having an insertion hole is provided with an outer peripheral surface cast by a casting material of a cast product and an exposed surface exposed from the casting material so as to face the insertion hole A casting method using a nut,
A taper surface that widens toward the exposed surface side is formed on the outer peripheral surface of the cap nut body, and a retaining means that enables the cap nut body to be held against the casting material is provided on the taper surface, The cap nut body is a cap nut for casting that is detachable via the tapered surface with respect to a sand mold model forming a sand mold as a mold,
Insert a fixing member into the cap nut for casting,
Attaching the cast cap nut to the sand mold model,
Filling the sand mold model with casting sand to form the sand mold,
While removing the sand mold model from the sand mold, the fixing member is supported by the sand mold by the fixing member,
A casting method using a cap nut for casting, wherein an outer peripheral surface of the cap nut for casting is cast into the cast material by pouring the casting material into the sand mold.

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