Length measuring device

A length measuring device is used for measuring a length of from a virtual intersection of the extension lines of two surfaces extending along the respective sides A1, A2 to ends of the respective sides of a bent member. The length measuring device is comprised of a rotary body 20 rotating about the virtual intersection as a center O and a scale body 30 having graduations (divisions). The rotary body 20 has a contacting side 20c with which one side of the bent member A is brought into contact, while the scale body 30 has a contacting side 30c with which the other side of the bent member A is brought into contact. The two contacting sides 20c, 30c are arranged on straight lines drawn through the virtual intersection.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to a length measuring device, in particular to a
 length measuring device which makes it possible to directly read a length
 of two sides of a bent member from a virtual intersection of the extension
 lines of two sides of a bent member folded with an arbitrary angle,
 wherein "the virtual intersection of two faces" means an intersection at
 which the extensions of two outer surfaces extending along the respective
 sides intersect each other in a meeting area (a bent area).
 2. Description of the Prior Art
 In plate processing, there are many cases where the processing of bent
 member A formed of two or more sides is made. However, since the bent
 member A is made by bending a plate, a bent area in which two sides A1, A2
 of bent member A as shown in FIGS. 1(a), 1(b) meets is not formed into an
 acute angle, but formed into a curved form.
 On the other hand, in the instruction in the drawing in plate processing,
 dimensions L1, L2, L3 from an intersection P of extension lines of two
 faces of a bent member is shown. However, since the actual bent area of
 the bent member is curved, it is impossible to directly read the length
 from the virtual intersection P the virtual an actual article.
 In the inspection of bent member, it is needed to measure dimensions L1,
 L2, L3. In a conventional job site, a board is put on one side for which
 measurement is made, while the other side is located on a holder, and a
 measurement of a length between the board and the upper surface of the
 holder is made using a vernier caliper. However, using this method, only
 an approximate value is obtained. Further, recently, three-dimensional
 measuring device and others appear, by which dimensions of from an
 intersection can be measured. However, the three-dimensional measuring
 device is extremely high in cost so that it cannot be easily applied.
 Further, when bending a plate so as to form a desired bent member, it is
 useful to know the respective dimensions (developed dimensions) of both
 straight faces and the bent area of the bent member formed from the plate.
 For example, developed dimensions corresponding to a bent member shown in
 FIG. 1(a) are as shown in FIG. 2. Therefore, if a ratio of dimension L to
 dimension L1, L2, which is dependent on a bending angle and a thickness of
 plate, is known, it is possible to know developed dimensions of plate by
 knowing dimensions L1, L2. To preset developed dimensions is specially
 useful for locating holes bored in a plate at a given position in a bent
 member.
 BRIEF SUMMARY OF INVENTION
 Accordingly, it is an object of the invention to provide a length measuring
 device which has a simple construction, handy to use, and besides enables
 to directly read dimensions of from an intersection of two faces of a bent
 member bent at a arbitrary angle.
 The present invention is characterized in that in a length measuring device
 for measuring a length from a virtual intersection of the extension lines
 of two outer surfaces extending along the respective sides, to ends of the
 respective sides of a bent member, the length measuring device comprises a
 rotary body rotating about the virtual intersection and a scale body
 having graduations (divisions). The rotary body has a contacting side with
 which one side of the bent member is brought into contact, while the scale
 body has a contacting side with which the other side of the bent member is
 brought into contact, and that the two contacting sides are arranged on
 straight lines drawn through the virtual intersection.
 In the present invention, a shape of a rotary body is not specially
 restricted. A rotary body is preferably a partially cut disk formed nearly
 into a fan-shape observing from the top, which is made by cutting a sector
 with a given angle about a center of a circular plate from the circular
 plate, the partially cut disk is rotatable about the center of the
 circular plate as a center of rotation, and at least one end extending in
 a radial direction of the partially cut disk forms a contacting side of
 the rotary body. In the description of the present application,
 "fan-shape" include a fan-shape having an angle more than 180.degree. .
 Further, in the present invention, a rotary body itself or a contacting
 side of the rotary body can be formed so as to be able to slide so that a
 length of from a center of a rotary body to ends of the body of rotation
 can be altered.
 In particular, when making a measurement for one side of a bent member
 having a complicated sectional form, for example having sides more than
 two, there is a case where it is advantageous to shorten dimension of
 contacting side so that another side does not interfere with a length
 measuring device.
 In the present invention, a means for rotating the rotary body is
 preferably mounted at a position other than the center of rotation of the
 rotary body. The means for rotating the rotary body can be preferably
 selected from the group consisting of a bearing inserted between the
 rotary body and the main body thereof, a fan-shaped guide groove which is
 mounted on a body of the length measuring device and which has a form
 formed along the locus of rotation of the fan-shaped rotary body, a
 concave guide and a covex guide which are provided on any of an opposed
 surfaces of the rotary body and the main body thereof, respectively, so as
 to be slidably engaged with each other, wherein the above-mentioned
 description does not mean to exclude an embodiment in which a shaft of
 rotation is provided at a center of rotation. Since it is feared that a
 thick shaft of rotation interferes with the measurement, for example, the
 diameter of shaft of rotation is minimized or a shaft of rotation is
 provided so as to able to be detachable so that the shaft of rotation can
 be pulled out when taking measurements.

DETAILED DESCRIPTION
 Referring to the drawings, an embodiment of the present invention is
 explained, FIG. 3(a) is a top view of the length measurement device
 according to a first embodiment of the present invention. The length
 measurement device is comprised of a planar base 1 having a rectangular
 form observing from the top, a rotary body 2 rotatably mounted on the
 upper surface of the base 1 at an end in the longitudinal direction of the
 base 1, and a scale body 3 mounted on the upper surface of the base 1
 extending in the longitudinal direction of the base 1.
 The rotary body 2 is comprised of a circular main body 2a, a fan-shaped
 raised body 2b formed integrally with the main body, and a contacting side
 2c formed by an end of the raised body 2b. The rotary body is formed into
 a normal circle, The rotary body is mounted on the base 1 so as to turn
 about a center of the circle as a center of rotation O. In taking
 measurements, a center of rotation O of the rotary body 2 is located on a
 virtual intersection P of the extensions of outer surfaces of two sides of
 a bent member A which is an object of measurements.
 In the embodiment, as shown in FIG. 3(b), bearings 4 are provided on the
 base 1, and the lower side of the main body 2a is engaged with the
 bearings 4 so that the rotary body 2 is rotatable. However, means for
 rotatably mounting the rotary body 2 on the base 1 is not restricted to
 this structure. Other means which can be selected by person having
 ordinary knowledge in the technical field can be applied.
 As to a shape of the rotary body 2 and a shape of the fan-shaped raised
 body, they are not restricted to them in the above-mentioned embodiment.
 In short, it is sufficient that the rotary body 2 is rotated about a
 virtual intersection as a center of rotation O and has a contacting side
 2c. As to the contacting side 2c, a starting point of extending of the
 contacting side 2c is not necessarily a center of rotation O. It is
 sufficient that the contacting side 2c is located on a straight line drawn
 through a virtual intersection P. Accordingly, for example, the rotary
 body 2 is not necessarily formed into a circle. It is not necessary that
 the raised body 2b has a fan-shape with a central angle 90.degree. (1/4
 circle), raised body 2b can be formed as a longitudinal member in such a
 manner that the peripheral portion thereof is used as a contacting side.
 In fact, with the regard to easiness of design, efficiency of assembly and
 others it is desirable that the rotary body 2 is formed generally into a
 circle and raised body 2b has a shape of 1/4 circle observing from the
 top.
 For the scale body 3, the construction of conventional vernier caliper is
 applied, wherein the scale body 3 is comprised of a main scale 3a in which
 the side of one end thereof is located close to a center of rotation O of
 the rotary body 2, while the side of the other end thereof is extended in
 the longitudinal direction of the base 1, and a sub scale 3b slidably
 mounted against the main scale 3a. The side of the other end of the scale
 body 3 is fixed on the base 1 through attaching member 3d. The side of one
 end of the scale body 3 forms a contacting side 3c, wherein the contacting
 side 3c is located on a straight line drawn through a center of rotation
 O. Further, the direction of the graduations of the scale body 3 is
 parallel to the longitudinal direction of the contacting side 3c. In the
 embodiment, the contacting side 3c has a starting point on a center of
 rotation. However, the starting point of the contacting side 3c can be
 located at a point distant from a center of rotation O. Further, the scale
 body is not necessarily a vernier caliper. If a length of from a center of
 rotation can be measured, the other means can be applied.
 A circular fixing member 5 is mounted at the peripheral portion of the
 rotary body 2 so that the rotary body 2 can be temporarily fixed at a
 desired position by turning a screw 5a in the advancing direction. In
 fact, a means for temporarily fixing the rotary body 2 is not restricted
 to this. Further, the fixing member is convenient if it is provided for
 the rotary body 2, but it is not necessarily needed.
 FIGS. 4(a)(b) and (c) and FIGS. 5(a)(b) and (c) show the second embodiment
 of the present invention, wherein in both drawings, (a) is a top view of
 the length measurement device, (b) is a top view, and (c) is a side
 elevation of a rotary body. The length measurement device is comprised of
 a planar scale body 30 having a rectangular form as observed from the top,
 and a rotary body 20 rotatably mounted on the side of one end of the scale
 body 30. For the scale body 30 in the same manner as the first embodiment,
 the construction of conventional vernier caliper is applied, wherein the
 scale body 30 is comprised of a main scale 30a forming a main body of the
 scale body 30 and a sub scale 30b slidably mounted against the main scale
 30a. One side of main scale 30 forms a contacting side 30c, and the
 contacting side 30c is located on a straight line drawn through a center
 of rotation O. Further, the extending direction of the contacting side 30c
 and the direction of the graduations of the scale body agree. The
 construction of the scale body 30 should not be restricted to the
 above-mentioned vernier caliper. In short, if a length of from the center
 of rotation O can be measured, another means can be applied.
 In the second embodiment, the rotary body 20 is comprised of bodies of
 rotation 20A and 20B of two kinds which are detachable so that the bodies
 of rotation 20A and 20B can be selectively applied according to arbitrary
 bending angle .theta. of bent member. The rotary body 20A is formed into a
 nearly half circle and is a partially cut disk having a cut portion 20c in
 a portion of a center of rotation. The rotary body 20A is advantageously
 used when an angle .theta. at which the extensions of two sides of a bent
 member A which is an object to be measured meet with each other is more
 than 90.degree..
 The rotary body 20B is formed into a nearly 3/4 circle and is a partially
 cut disk having a cut portion 20c in a portion of a center of rotation.
 The rotary body 20B is advantageously used when an angle .theta. at which
 the extensions of two sides of a bent member A which is an object to be
 measured meet with each other is below 90.degree.. The peripheral portion
 of the rotary body raising in the radial direction forms a contacting side
 20c, wherein the contacting side 20c is located on a straight line drawn
 through the center of rotation O. The rotary body 20A, 20B are suitably
 selected according the bending angle .theta. of a bent member A. The
 shapes(angles) of the bodies of rotation 20A, 20B are not restricted to
 them shown in the drawings. For example, the body if rotation 20A can be
 formed into a fan-shape with angle of 170.degree. and the rotary body 20B
 can be formed into a fan-shape with angle of 250.degree..
 FIG. 6(a) is a schematic perspective view of the length measurement device
 according to the second embodiment, and FIG. 6(b) is a side elevation, and
 FIG. 6(c) is a bottom view of a side of an end of a scale body, wherein
 the lower side of the slide of one end of the scale body 30 is formed with
 a rotary guide groove 40a of the rotary body 20 by cutting a portion of
 the scale body 30. The rotary guide groove 40a is a circular arc-shaped or
 half doughnut-shaped concave portion. The partially-cut-circle-shaped
 rotary body 20 is engaged with the scale body 30 so that the rotary body
 can be rotated about the intersection of two faces of a bent member A as a
 center of rotation by turning the rotary body 20 while sliding. The scale
 body 30 is formed with a circular arc-shaped slit 40b at a portion
 corresponding to the guide groove 40a so that the rotary body 20 is
 prevented from slipping out from the scale body 30 by regulating movement
 of a pin 20a attached to a pin hole 20d and projecting from the rotary
 body 20 along the slit 40b. It is preferable that the height of the rotary
 body 40a is nearly equal to the thickness of the rotary body 20 and the
 lower face is flush with the lower face of the rotary guide groove 40a.
 Means for rotating the rotary body 20 is not restricted to the
 above-mentioned means. For example, any one of opposed faces of the scale
 body 30 and the rotary body 20 is formed with a circular arc-shaped convex
 portion, while the other face can be formed with a circular arc-shaped
 concave portion so that the circular arc-shaped convex portion and the
 circular arc-shaped concave portion can be engaged with each other so as
 to be able to slide in the direction of rotation. Or, another means which
 can be also suitably selected by person having ordinary knowledge in the
 technical field. Further, it is possible to measure dimensions of a bent
 member made by bending both ends of a plate at arbitrary angle, by
 providing another rotary body at an end of the slidable sub scale 30b on
 the side of the rotary body 20.
 FIGS. 7(a)(b) and (c) show a length measurement device according to a third
 embodiment of the present invention, which is an alternation of the second
 embodiment, and had a character in the construction of a rotary body 200.
 The rotary body 200 is comprised of a half-circular bodies of rotation
 200A, 200C which lie on top of another and are engaged with each other in
 such a manner that both bodies of rotation are able to rotate to each
 other about a center of rotation O so that the rotary body 200 can be
 accommodated to an arbitrary bending angle .theta. by shifting one rotary
 body 200B against the other rotary body 200A while sliding in the rotary
 direction. In FIG. 7(b), a peripheral portion raising in the radial
 direction forms a contacting side 200c. In the embodiment shown in the
 drawings, the rotary body 200 is formed of two bodies of rotation 200A,
 200B. However, it is not needed that angles of the bodies of rotation
 200A, 200B are nearly 180.degree., and that shapes of both are the same to
 each other. Further, it is possible that the rotary body is formed of
 three or more bodies of rotation. Means for slidably connecting bodies of
 rotation 200A, 200B is not specially restricted. For example, the bodies
 of rotation 200A, 200B can be formed with a circular arc-shaped guide slit
 200e so that a guide body 200f projected from one rotary body can be moved
 in a guide slit 200e.
 Then, a method of measurement by a length measuring device of the present
 invention is explained. FIG. 8 shows the measurement by the length
 measuring device according to the first embodiment of the present
 invention. First, an end of a bent member is brought into contact with the
 upper face of the main body 2a by locating a meeting portion of the
 extension lines of two sides (bent portion) close to the center of
 rotation O so that one side A1 of the bent member A which is an object to
 be measured is brought into contact with the contacting side 3c. Then, the
 contacting side 2c of the raised portion 2b is brought into contact with
 the other side A2 of the bent member A so that the position of the bent
 body is kept by inserting the bent body A between the two contacting sides
 2c, 3c. Then, it is possible to measure a length of from the intersection
 by reading graduation of the scale body 3. The explanation about how to
 read graduation of vernier caliper forming the scale body 3 is omitted,
 since it is obvious for person having ordinary knowledge in the technical
 field. When measuring a length of the other side A2, the other side A2 is
 brought into contact with the contacting side 3c of the scale body 3, and
 the same operation is carried out.
 A method of measurement by a length measuring device according to the
 second embodiment is explained referring to FIGS. 4(a)(b) and (c), and
 FIGS. 5(a)(b) and (c). First, one side A1 which is an object to be
 measured is brought into contact with the contacting side 30c of the scale
 body 30. Then, the contacting side 20c is brought into contact with the
 other side A2. Then, it is possible to measure a length of from the
 intersection by reading graduation of the scale body 30. When measuring a
 length of the other side A2, the other side A2 is brought into contact
 with the contacting side 30c of the scale body 30, and the same operation
 is carried out. In the measurement by the length measuring device
 according to the second embodiment, even if ends of a bent member A are
 not positioned on the same plane, good measurement can be carried out. In
 this point, the second embodiment is more advantageous than the first
 embodiment. In the first embodiment, since a measurement is made under the
 state where ends of a bent member are brought into contact with the upper
 face, in case where ends of a bent member is cut into a complicated shape,
 the measurement is difficult.
 A method of measurement by a length measuring device according to the third
 embodiment is the same with a method of measurement by a length measuring
 device according to the second embodiment. For convenience' sake, an
 example of a bent member having only two sides is shown. However, a bent
 member can be bent in such a manner that the bent member has a three or
 four observing from the side. Further, although the length measuring
 device is used for measuring dimensions of a bent member A having a curved
 portion, the length measuring device can be applied for measuring a length
 of a member having an acute angle portion or pointed part, Further,
 although the present invention is directed for a bent member, even in case
 where bent member A is a pipe material, the measurement of a length of the
 bent member A formed of a pipe material is made possible by putting the
 circumference of the pipe material on a contacting side.
 As above-mentioned, according to the present invention, a length of from an
 intersection of the extensions of two surfaces of a bent member with
 arbitrary angle can be easily directly read.