Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Reexamination Certificate
1999-08-11
2001-09-18
Hirshfeld, Andrew H. (Department: 2859)
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
C033S452000, C033S495000
Reexamination Certificate
active
06289598
ABSTRACT:
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 A
1
, A
2
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 L
1
, L
2
, L
3
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 L
1
, L
2
, L
3
. 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 L
1
, L
2
, 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 L
1
, L
2
. 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° .
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.
REFERENCES:
patent: 226429 (1880-04-01), Varnum
patent: 3561122 (1971-02-01), Beckwell
patent: 3623231 (1971-11-01), Holt
patent: 4472883 (1984-09-01), Ortega
patent: 4660293 (1987-04-01), Kovacs
patent: 5375340 (1994-12-01), Gerritsen
patent: 5426859 (1995-06-01), Concari et al.
patent: 5687628 (1997-11-01), Liao
Hirshfeld Andrew H.
Tanabe Seisa sho Limited
Townsend & Banta
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