JP2010047989A - Screw point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw point for a Swedish sounding test which surely prevents the breakage of a connecting portion or dropping of the connecting portion from the body of the screw point. <P>SOLUTION: The screw point 1 for the Swedish sounding test includes the body 2 having a plurality of ridges 11 formed on its outer periphery into a spiral shape along the direction of going from a base end 2a toward a front end 2b, and a fixing portion 3 formed integrally on the base end 2a of the body 2 for fixing the body 2 to a rod. The fixing portion 3 is formed as a rolling screw made by rolling machining. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a screw point used for a Swedish sounding test.

  In general, when building a building, a strength test is performed on the ground for building prior to building. As this type of strength test, a Swedish sounding test (hereinafter also simply referred to as “test”) defined in Japanese Industrial Standard (JIS) -A1221 has been known. In this test, a rod with a screw point attached to the tip of the rod is rotated while being loaded, and the screw point is pushed into the ground by a predetermined depth. The strength of the ground is determined based on the number of rotations as 1. In this case, for example, as disclosed in Japanese Patent Laid-Open No. 9-53224, this screw point is provided with a conical tip at one end and a thread for connecting and fixing to the rod at the other end. And a spiral blade is formed on the outer periphery from the other end toward the one end (hereinafter, the portion where the blade is formed is also referred to as a “main body portion”). In this case, as a method of manufacturing this type of screw point, for example, an intermediate body composed of a columnar portion serving as a connecting portion and a main body portion is manufactured by forging or the like, and then a screw cutting lathe or the like is used. A method for forming a threaded portion by cutting a cylindrical portion is known.

JP-A-9-53224 (page 4, FIG. 1)

  However, the conventional screw points including the above screw points have the following problems. That is, when manufacturing a conventional screw point, as described above, the connecting portion is formed by cutting using a screw lathe or the like. In this case, when performing cutting using a thread lathe or the like, as shown in FIG. 7, in addition to the length corresponding to half the width of the cutting bit 400, the cutting bit is separated from the cutting surface (relief). ) Can not be formed on the base end portion 303a of the connecting portion 303 (the boundary portion between the main body portion 302 and the connecting portion 303) by the length necessary for the above-described portion. It is necessary to form a small diameter in accordance with the diameter of the valley portion. On the other hand, in the test described above, when a rod with a screw point attached is rotated and pushed into the ground, a large rotational moment is applied to the screw point. However, in the conventional screw point, since the base end portion 303a of the connecting portion 303 is formed with a small diameter, stress concentration is likely to occur in that portion. For this reason, the conventional screw point has a problem that the connecting portion 303 may be broken (damaged) due to the stress concentration generated in the base end portion 303a of the connecting portion 303 due to the rotational moment applied during the test. There is a point.

  In this case, a screw hole is formed in the base end of the main body, the base end of the headless screw formed separately from the main body is screwed into the screw hole of the main body, and the screw protruding from the main body is A screw point using the distal end side as a connecting portion is known, and in this configuration, stress concentration can be avoided because the diameter of the base end portion of the connecting portion is the same as the diameter of the other portion. However, in this configuration, it is necessary to fix the base end portion of the headless screw (connecting portion) to the main body portion (screw hole) using an adhesive in order to prevent the headless screw from dropping (disconnecting). In addition to the complexity of the process, there is a problem that the fixing force is insufficient with only the adhesive, and there is a possibility that the connecting portion may fall off from the main body when a large rotational moment is applied during the test.

  The present invention has been made in view of such problems, and it is a main object of the present invention to provide a screw point for a Swedish sounding test that can reliably prevent breakage of the connecting portion and dropout of the connecting portion from the main body portion. And

  In order to achieve the above object, the screw point according to claim 1 includes a main body portion having a plurality of ridges formed in a spiral shape along a direction from the proximal end side toward the distal end side, A screw point for a Swedish sounding test that is integrally formed with the base end portion of the main body portion and has a fixing portion for fixing the main body portion to the rod, and the fixing portion is formed by rolling. Made of rolled screws.

  The screw point according to claim 2 is the screw point according to claim 1, wherein the main body is formed by cutting.

  According to the screw point of the first aspect, the fixed portion integrally formed on the base end portion of the main body portion is configured by the rolling screw formed by rolling, so that the base end portion of the fixed portion has a small diameter. Since the part is not formed and the strength of the fixed part is increased as a whole, the base part of the fixed part has a small diameter even if a large rotational moment is applied to the screw point with rotation during the Swedish sounding test. Unlike the conventional screw point formed in (1), the occurrence of stress concentration at the base end portion of the fixed portion can be prevented, so that the situation where the fixed portion is broken can be reliably prevented. Further, according to this screw point, since the fixing portion and the main body portion are integrally formed, a headless screw formed separately from the main body portion is screwed into the screw hole of the main body portion and fixed by an adhesive or the like. Unlike the configuration, even if a large rotational moment is applied to the screw point, it is possible to reliably prevent the fixing portion from falling off the main body portion.

  Moreover, according to the screw point of Claim 2, compared with the structure which forms a main-body part by forging, for example, compared with the structure which forms a main-body part by forging, many types of screw points from which a size and a shape differ are formed. The manufacturing cost at the time of manufacturing can be reduced sufficiently.

  Hereinafter, the best mode of a screw point according to the present invention will be described with reference to the accompanying drawings.

  First, the Swedish sounding tester 100 (hereinafter, also simply referred to as “tester 100”) shown in FIG. 1 will be described. The tester 100 is a manual tester for performing a Swedish sounding test defined in JIS-A1221, using the screw point 1 according to the present invention. As shown in FIG. The connecting rod 102, the handle fixing portion 103, the handle 104, the clamp 105, a plurality of weights 106, 106,. For example, the rod 101 is formed in a columnar shape, and its length is defined as 800 mm. In this case, a screw hole 101a (see FIG. 6) is formed in one end (the lower end in the figure) of the rod 101, and a male screw (not shown) is formed in the other end (the upper end in FIG. 1) of the rod 101. ) Is formed. Furthermore, a scale is drawn on the rod 101 every 250 mm from one end. The extension rod 102 is a rod for adding to the rod 101 during the test, and its length is defined as 1000 mm. Otherwise, the extension rod 102 has the same specifications as the rod 101.

  As shown in FIG. 1, the handle fixing portion 103 is connected to the upper end portion of the rod 101 to fix the handle 104. The handle 104 passes through the handle fixing portion 103 and is fixed to the handle fixing portion 103 so as to be orthogonal to the rod 101 (or the connecting rod 102). The clamp 105 is formed in a disk shape, and a center hole that allows the rod 101 (or the connecting rod 102) to pass therethrough is formed at the center thereof. The clamp 105 is fixed to a position spaced from the upper end of the rod 101 by a predetermined length toward the lower end with the rod 101 passing through the center hole, and holds the weight 106 placed thereon. . The weights 106 are each formed in a disk shape, for example. The weight 106 is formed with a center hole formed at the center and a notch from the outer periphery to the center hole, and the rod 105 is inserted into the center hole using the notch. Placed on top. In this case, in the Swedish sounding test, two weights 106, 106 each having a weight of 10 kg and three weights 106, 106, 106 each having a weight of 25 kg are used. The bottom plate 107 is formed, for example, in a disc shape, and has a hole formed through the screw point 1 and the rod 101 at the center. In this case, as shown in the figure, the bottom plate 107 is placed on the ground 200 to be tested during the test. The tester 100 is defined so that the total weight including the screw point 1 is about 5 kg as an example.

  On the other hand, the screw point 1 is an example of the screw point according to the present invention, and is manufactured in accordance with the provisions of JIS-A1221. Specifically, as shown in FIG. 2, the screw point 1 includes a main body portion 2 and a fixing portion 3. The main body 2 has four ridges (a plurality of examples in the present invention) spiraling along the direction from the base end 2a (the upper end in the figure) to the tip 2b (the lower end in the figure). 11 are formed on the outer peripheral portion thereof. In this case, the direction of rotation of the spiral is defined to be clockwise when viewed from the base end 2a side. The main body 2 has, for example, a length T1 from the base end 2a to the tip 2b of 200 mm and a length T2 from the maximum diameter 2c having the maximum outer diameter to the tip 2b of 150 mm. It is stipulated in. The main body 2 has, for example, an outer diameter W1 of the maximum diameter portion 2c defined as 33 mm and an outer diameter W2 of the distal end portion 2b defined as 5 mm, as the maximum diameter portion 2c moves toward the distal end portion 2b. The outer diameter is formed so as to gradually become smaller. In this case, the main body 2 is formed by cutting a rod-like (cylindrical or conical shape) steel material having a hardness equal to or higher than S50C defined in JIS-G4051, for example. It is formed in the shape.

  The fixing portion 3 is a portion for fixing the screw point 1 to the rod 101, and is integrally formed with the main body portion 2 as shown in FIG. Further, as shown in the figure, for example, the fixing portion 3 is defined such that a length T3 protruding from the base end surface (upper end surface) of the main body portion 2 is 20 mm or more, and an outer diameter W3 thereof is It is specified to 14 mm. In this case, as will be described later, the fixing portion 3 has a thread 31 formed on the outer peripheral surface thereof by rolling. That is, the fixed portion 3 is configured by a rolling screw (in this example, a rolling screw having a name of M14) formed by rolling.

  Next, an example of the manufacturing method of the screw point 1 is demonstrated.

  First, the intermediate body 21 shown in FIG. 3 is produced by cutting. Specifically, by using a cutting machine, for example, by cutting the columnar steel material 20 indicated by a broken line in the figure, an area that will later become the main body 2 (first area 20a shown in the figure). ) Are formed with four ridges 11 having a spiral shape (hereinafter, the portion where the ridges 11 are formed is also referred to as “intermediate body 22”), and a region that later becomes the fixing portion 3 (see FIG. In the second region 20b), a columnar portion having a diameter of about 12.7 mm is formed (hereinafter, the portion formed in a columnar shape is also referred to as “projection portion 23”). In this case, by forming the intermediate body portion 22 (that is, the body portion 2) by cutting, for example, various types of screw points having different sizes and shapes as compared with the case where the body portion 2 is formed by forging. The manufacturing cost when manufacturing 1 is sufficiently reduced.

  Subsequently, the rolling process which forms the thread 31 on the projection part 23 of the intermediate body 21 produced as mentioned above using a rolling apparatus is performed. Here, in this rolling apparatus, as shown in FIGS. 4 and 5, as an example, one or a plurality of screw threads 61 having the same shape as the screw threads 31 are formed on the outer peripheral surface (two in this example). ) Is pressed against the surface (processed surface) of the protrusion 23 and rotated to plastically deform the processed surface to form the thread 31. In this case, a thread 61 is formed on the rolling die 51 from the base end 51a (the right end in both figures) to the tip 51b (the left end in both figures). For this reason, as shown in FIG. 5, by moving the tip end portion 51b of the rolling die 51 to the base end portion 23a (the boundary portion between the intermediate body main body portion 22 and the protruding portion 23) of the protruding portion 23, the rolling is performed. The screw thread 61 of the die 51 can be surely pressed to the base end portion 23 a of the protrusion 23. As a result, in the rolling process using this rolling apparatus, unlike the case where the thread is formed by cutting, the tip of the projection 23 is formed without forming a small-diameter portion in the base end 23a of the projection 23. The thread 31 can be formed over almost the entire region from the portion 23b to the base end portion 23a. In addition, it is preferable to perform the rolling process in a state in which the protruding portion 23 is maintained at room temperature, but depending on the type of steel material (hardness, etc.) used for the production of the intermediate body 21, the protruding portion 23 is heated in the heated state. It is also possible to adopt a method for performing fabrication.

  In this case, the strength of the cutting screw produced by the cutting process may decrease because the fiber flow (fibrous metal structure) in the steel material is cut during the cutting process. On the other hand, it is known that a rolled screw produced by a rolling process causes a plastic deformation of a processed surface, so that there is little fiber flow cutting, and work hardening occurs with plastic deformation. For this reason, by forming the screw thread 31 by rolling as described above, it is possible to increase the strength of the protrusion 23 (that is, the fixed portion 3) and sufficiently improve the durability. Further, in the rolling process, the processed surface is plastically deformed to form the screw thread 31 as described above, and as a result, cutting waste is not generated as in the cutting process. It can be omitted or simplified. Further, the rolling process can shorten the processing time as compared with the cutting process. Therefore, by forming the thread 31 by the rolling process, it is possible to improve the processing efficiency when the fixing portion 3 is created, and hence the manufacturing efficiency of the screw point 1.

  Subsequently, the intermediate body 21 after the formation of the thread 31 by the rolling process is heat-treated. In this case, it is preferable to perform the partial heat treatment so that the intermediate body portion 22 has a predetermined high hardness and the protrusion 23 has a lower hardness than the intermediate body portion 22. Subsequently, a coating is formed on the surface of the intermediate body 22 in the intermediate body 21 after the heat treatment by plating. As described above, the main body portion 2 subjected to the heat treatment and the plating treatment, and the fixing portion 3 having the thread 31 formed integrally with the main body portion 2 and formed by the rolling process (that is, composed of the rolling screw). A screw point 1 with a fixing part 3) is completed.

  Next, a method of performing a Swedish sounding test using the screw point 1 and the tester 100 will be described with reference to the drawings.

  Prior to the test, the tester 100 is assembled. Specifically, the rod 101 is passed through the central hole of the clamp 105, and the clamp 105 is fixed to the rod 101 at a position spaced from the upper end of the rod 101 by a predetermined length toward the lower end. Next, the handle fixing portion 103 is fixed to the upper end portion of the rod 101. Next, the handle 104 is passed through the handle fixing portion 103, and the handle 104 is fixed so as to be orthogonal to the rod 101.

  Subsequently, the screw point 1 is attached to the lower end portion of the rod 101. Specifically, as shown in FIG. 6, the fixing portion 3 of the screw point 1 is screwed into the screw hole 101 a of the rod 101. In this case, when forcibly screwing in the state where the fixing portion 3 is inclined with respect to the screw hole 101a, the fixing portion 3 and the screw hole 101a may not be properly engaged with each other, and both may be deformed. Therefore, at the start of screwing, it is preferable to screw the main body 2 of the screw point 1 directly by hand (manually) without using a tool. Next, after the fixing portion 3 is screwed into the screw hole 101a to the extent that manual screwing is possible, the fixing portion 3 is further screwed using a tool (not shown).

  Here, in this screw point 1, the thread 31 was formed by the rolling process (the fixing part 3 was configured by the rolling screw), so that almost the entire region from the distal end part 3b to the proximal end part 3a of the fixing part 3 was obtained. A thread 31 is formed over the entire area. For this reason, it is possible to completely screw the fixing portion 3 into the screw hole 101a. Next, after screwing the fixing portion 3 into the screw hole 101a until the base end portion 2a of the main body portion 2 and the tip end surface of the rod 101 contact each other, a sufficient force is applied to the tool to tighten the screw point 1 to the rod 101. The screw point 1 and the rod 101 are securely fixed.

  Next, as shown in FIG. 1, the bottom plate 107 is placed at a predetermined test location on the ground 200 to be tested. Next, the screw point 1 of the assembled tester 100 is passed through the center hole of the bottom plate 107. At this time, when the screw point 1 is inserted into the ground 200 due to its own weight (about 5 kg in this case), the screw point 1 and the insertion of the screw point 1 and the rod 101 (moving downward) are stopped. Measure the amount of insertion. Subsequently, a 10 kg weight 106 is placed on the clamp 105 of the tester 100 to increase its own weight to about 15 kg. At this time, when the screw point 1 is further inserted due to an increase in its own weight, the insertion amount of the screw point 1 is measured when the insertion is stopped. Next, the weight of the tester 100 is sequentially changed to about 25 kg, about 50 kg, about 75 kg and about 100 kg by exchanging or adding the weight 106 placed on the clamp 105, and the insertion amount of the screw point 1 is changed in the same manner as described above. Measure. In this case, when the clamp 105 hits the bottom plate 107 by inserting the screw point 1, the handle fixing portion 103 and the handle 104 are removed from the rod 101, and the extension rod 102 shown in the figure is connected to the upper end portion of the rod 101. After that, the removed handle fixing portion 103 and handle 104 are fixed to the upper end portion of the connecting rod 102, and the clamp 105 is pulled upward and fixed.

  Next, after the insertion of the screw point 1 is stopped in a state where the weight of the tester 100 is about 100 kg, the entire tester 100 is turned clockwise using the handle 104 so that a downward force is not applied (ridge portion). 11 direction). At this time, the number of half rotations required until the screw point 1 is further inserted by a length of 250 mm from the position where it was stopped by its own weight of about 100 kg is recorded (the number counted when the half rotation of the rod is 1). Thereafter, every time the amount of insertion increases by 250 mm, the number of half revolutions required is recorded. In this case, for example, when the number of half revolutions until the screw point 1 hits a hard formation and the insertion amount increases by 50 mm becomes 50 times or more, the measurement is stopped. Next, while rotating the entire tester 100 counterclockwise (opposite to the time of insertion), the rod 101 (joint rod 102) and the screw point 1 are pulled out from the ground 200, and then the insertion amount for each weight. The strength of the ground 200 is evaluated based on the measured value and the half rotation number required every time the insertion amount increases by 250 mm.

  In this case, in this screw point 1, the fixed portion 3 is configured by a rolling screw that is formed by rolling and does not have a small diameter portion formed on the base end portion 3 a and has increased strength. . For this reason, in this screw point 1, even if a large rotational moment is applied to the screw point 1 with the rotation during the test, unlike the conventional screw point in which the base end portion is formed with a small diameter, the fixed portion As a result of the occurrence of stress concentration at the base end portion 3a of the No. 3, it is possible to reliably prevent the fixing portion 3 from being broken (broken). In addition, since the fixing portion 3 and the main body portion 2 are integrally formed, unlike a configuration in which a headless screw formed separately from the main body portion is screwed into a screw hole of the main body portion and fixed by an adhesive or the like, Even if a large rotational moment is applied to the screw point 1, it is possible to reliably prevent the fixing portion 3 from falling off the main body portion 2.

  As described above, according to the screw point 1, the fixed portion 3 formed integrally with the base end portion 2a of the main body portion 2 is constituted by the rolling screw formed by the rolling process. Since the end portion 3a is not formed with a small-diameter portion and the strength of the fixed portion 3 is increased as a whole, even if a large rotational moment is applied to the screw point 1 with the rotation during the test, the base end portion Unlike conventional screw points having a small diameter, stress concentration at the base end portion 3a of the fixing portion 3 can be prevented, so that the fixing portion 3 can be reliably prevented from breaking. it can. Moreover, according to this screw point 1, since the fixing | fixed part 3 and the main-body part 2 are integrally formed, the headless screw formed separately from the main-body part is screwed in the screw hole of a main-body part, adhesives, etc. Unlike the configuration in which the fixing portion 3 is fixed, even if a large rotational moment is applied to the screw point 1, it is possible to reliably prevent the fixing portion 3 from falling off the main body portion 2.

  Moreover, according to this screw point 1, since the main-body part 2 was formed by cutting process, compared with the structure which forms the main-body part 2 by forging, for example, many types of screw points 1 from which a size and a shape differ are different. The manufacturing cost at the time of manufacturing can be reduced sufficiently.

  In addition, this invention is not limited to said structure. For example, the main body 2 is formed to have a predetermined high hardness by heat treatment, and the example in which the fixing portion 3 is formed to have a lower hardness than the main body 2 has been described above. It is also possible to adopt a configuration that is formed as described above. Moreover, the structure which does not heat-process with respect to the main-body part 2 and the fixing | fixed part 3, and the structure which does not form a film in the surface of the main-body part 2 are also employable. Further, the dimensions of the main body 2 and the fixing portion 3 described above are examples and can be changed as appropriate.

  In addition, although an example in which the screw point 1 is used in the manual tester 100 has been described above, it is needless to say that the screw point 1 can be used in an automatic tester. The screw point 1 can also be used in other tests based on the Swedish sounding test.

2 is a configuration diagram showing a configuration of a tester 100. FIG. 2 is a plan view of a screw point 1. FIG. 3 is a plan view of an intermediate body 21. FIG. FIG. 6 is a first explanatory diagram for explaining a method of forming a screw thread 31 on the protrusion 23 of the intermediate body 21. FIG. 10 is a second explanatory diagram for describing a method of forming a screw thread 31 on the protrusion 23 of the intermediate body 21. It is explanatory drawing for demonstrating the attachment method of the screw point 1 with respect to the rod 101. FIG. It is explanatory drawing for demonstrating the method to manufacture the conventional screw point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw point 2 Main-body part 2a Base end part 2b Tip part 3 Fixing part 3a Base end part 3b Tip part 11 Ridge part 31 Thread 100 Tester 101 Rod

Claims (2)

A plurality of ridges spiraling along the direction from the base end side to the tip end side are formed on the outer peripheral portion of the main body portion, and the base end portion of the main body portion is integrally formed with the main body portion. A screw point for a Swedish sounding test with a fixing part for fixing the screw to the rod,
The fixing portion is a screw point configured by a rolling screw formed by a rolling process.   The screw point according to claim 1, wherein the main body is formed by cutting.

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