U.S. patent application number 13/129207 was filed with the patent office on 2011-11-10 for screw tensioning device.
This patent application is currently assigned to Wagner Vermogensverwaltungs- GMBH & Co.KG. Invention is credited to Claudia Beyert-Wagner, Bernd Thelen, Gisela Wagner, Martina Wagner-Kuerten, P. H. Wagner.
Application Number | 20110271798 13/129207 |
Document ID | / |
Family ID | 41647092 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110271798 |
Kind Code |
A1 |
Wagner; P. H. ; et
al. |
November 10, 2011 |
SCREW TENSIONING DEVICE
Abstract
The screw tensioning device comprises a support tube (12), a
cylinder member (15) and a piston section (17). The piston section
serves for moving a tensioning bolt (20) screwed onto the thread of
a threaded bolt (31). Provided according to the invention is a
depth measuring device (35), which presents an externally visible
indication of the screw-in depth (ET) of the threaded bolt (31).
This ensures that, when the threaded bolt (31) undergoes extension
under strain, there is a threaded engagement with the tensioning
bolt (20) along a sufficiently long distance. This avoids the
hazard that the screw tensioning device might break off from the
threaded bolt.
Inventors: |
Wagner; P. H.;
(Much-Birrenbachshohe, DE) ; Thelen; Bernd; (Much,
DE) ; Wagner; Gisela; (Much, DE) ;
Wagner-Kuerten; Martina; (Much, DE) ; Beyert-Wagner;
Claudia; (Much, DE) |
Assignee: |
Wagner Vermogensverwaltungs- GMBH
& Co.KG
Much
DE
|
Family ID: |
41647092 |
Appl. No.: |
13/129207 |
Filed: |
November 3, 2009 |
PCT Filed: |
November 3, 2009 |
PCT NO: |
PCT/EP09/64545 |
371 Date: |
May 13, 2011 |
Current U.S.
Class: |
81/57.38 |
Current CPC
Class: |
B25B 29/02 20130101;
B23P 19/067 20130101 |
Class at
Publication: |
81/57.38 |
International
Class: |
B25B 29/02 20060101
B25B029/02; B23P 19/06 20060101 B23P019/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 14, 2008 |
DE |
20 2008 015 148.1 |
Claims
1-6. (canceled)
7. A screw tensioning device for stretching a threaded bolt
carrying a nut, said screw tensioning device comprising a support
tube and a cylinder member provided in the axial extension of the
support tube, said cylinder member surrounding an axially moveable
piston section, and comprising a tensioning bolt extending through
the piston section and arranged in engagement with the piston
section so as to be axially entrained, wherein the tensioning bolt
comprises an axial channel provided with a depth measurement device
for indicating the axial position of the end of the threaded bolt
relative to the tensioning bolt.
8. The screw tensioning device of claim 7, wherein the tensioning
bolt comprises an axial threaded bore for screwing the threaded
bolt thereinto, and that the threaded bore terminates at and
end-side edge of the tensioning bolt.
9. The screw tensioning device of claim 7, wherein the depth
measuring device comprises a measurement rod arranged to be axially
movable in said channel of the tensioning bolt, said measurement
rod on one end thereof being provided with an abutment portion and
on the other end being provided with a marking adapted to project
from a casing of the screw tensioning device.
10. The screw tensioning device of claim 9, wherein the tensioning
bolt is provided with a spring biasing the measurement rod toward
said second end.
11. The screw tensioning device of claim 7, wherein that the depth
measuring device is configured to present an acceptance marking
when the end of the threaded bolt has a distance at least equal to
D from the abutment face, D being the thread diameter of the
threaded bolt.
12. The screw tensioning device of claim 7, wherein that the depth
measuring device emits an optical and/or acoustic signal when the
screw-in depth of the threaded bolt is in a predetermined range.
Description
[0001] The invention relates to a screw tensioning device for
stretching a threaded bolt carrying a nut, said screw tensioning
device comprising a support tube and a cylinder member provided in
the axial extension of the support tube, said cylinder member
including an axially moveable piston section, and comprising a
tensioning bolt extending through the piston section and arranged
in engagement with the piston so as to be axially entrained
thereby.
[0002] Screw tensioning devices are known for the purpose of
tightening and releasing highly stressed screw connections. A screw
tensioning device has the function of exerting a precisely
predetermined biasing force onto the screw connection in order to
allow for the tightening or releasing of the nut of the screw
connection that had been threaded onto a threaded bolt. For
tightening or releasing the nut, the screw tensioning device will
be screwed onto the thread--projecting beyond the nut--of the
threaded bolt and then be subjected to hydraulic pressure. The
screw-in depth of the threaded bolt into the tensioning bolt must
have a length of at least 1.times.D, with D being the diameter of
the threaded bolt, for ensuring that the threaded bolt will not be
damaged by the tensioning process. Failure to maintain a projecting
length of 1.times.D of the bolt will entail the danger that the
screw tensioning device tears off, resulting in hazard to persons
and objects.
[0003] In DE 10 2005 015 922 B4, a screw tensioning device is
described which is provided with a measurement rod for measuring
the relative displacement of the thread end of the threaded bolt
relative to the hydraulic cylinder and casing, respectively, of the
screw tensioning device. Thereby, however, one will merely obtain a
measure of the respective stretch of the threaded bolt but no
information yet on whether the tensioning bolt has been screwed
onto the threaded bolt to a sufficient extent.
[0004] It is an object of the invention to provide a screw
tensioning device wherein the screw-in depth is visualized in a
simple manner so that the checking of the minimum projecting length
of the bolt will not require additional tools or working steps.
[0005] The screw tensioning device of the invention is defined by
claim 1. It is characterized in that the tensioning bolt is formed
with an axial bore comprising a depth measuring device for
indication of the axial position of the end of the threaded bolt
relative to the tensioning bolt. Thus, the screw tensioning device
is provided with an integrated depth measuring device which
comprises an externally visible gauge indicating the measure of the
projecting length of the bolt.
[0006] The invention makes it possible, without additional
provisions on the screw tensioning device, to detect whether the
required projecting length of the bolt is maintained. Thereby,
handling the screw tensioning device is facilitated and the time
required for correctly tightening or releasing the screw connection
is reduced. The interior depth measuring device is encapsulated in
a manner keeping it free from external influences which might cause
damage or might impair the functioning of the device. In the
process of screw-mounting the hydraulic tensioning device, the
projecting length of the thread will be automatically measured and
respectively checked and will be visually indicated.
[0007] According to a preferred embodiment of the invention, it is
provided that the tensioning bolt comprises an axial threaded bore
for screwing the threaded bolt thereinto, and that the threaded
bore terminates at and end-side edge of the tensioning bolt. The
lower end of the threaded bore has the function of a reference
position forming the basis from where the screw-in depth of the
threaded bolt will be measured.
[0008] Said depth measuring device preferably comprises a
measurement rod, arranged to be axially movable in a channel of the
tensioning bolt, which on one end is provided with an abutment
portion and on the other end is provided with a marking adapted to
project from a casing of the screw tensioning device. Said
measurement rod can project from the casing of the screw tensioning
device. On this end of the measurement rod, said marking is
arranged, e.g. in the form of a green area. If the marking is
visible from the outside, this will indicate a correct projecting
length of the bolt. If, however, the acceptance marking is not
visible, the projecting length is too short. The measurement rod
can also be provided with a marking indicating an incorrect state,
e.g. in red color, which, if visible, will signal an insufficient
projecting length.
[0009] According to a preferred embodiment of the invention, the
tensioning bolt is provided with a spring biasing the measurement
rod toward said second end. Under the effect of the spring, the
measurement rod is forced in the direction toward the threaded bolt
and into tight abutment on the end face of the threaded bolt.
[0010] An exemplary embodiment of the invention will be explained
in greater detail hereunder with reference to the drawings.
[0011] In the drawings, the following is shown:
[0012] FIG. 1 is a view of the screw tensioning device, and
[0013] FIG. 2 is a longitudinal sectional view of the screw
tensioning device.
[0014] The hydraulic screw tensioning device illustrated herein
comprises a casing 10 which is substantially cylindrical and has an
upper end wall 11, while the lower end is formed by a support tube
12 with an open bottom. A hydraulic connector 13 is arranged
laterally on casing 10. Further provided is a gear transmission 14
which can be rotated by use of a tool for thus rotating the nut
seated on the threaded bolt.
[0015] Above said support tube 12, casing 10 comprises a cylinder
member 15 with a plurality of hydraulic cylinders 16, all of them
being arranged hydraulically parallel and connected to said
hydraulic connector 13. An axially moveable piston section 17
includes the pistons 18 which can be moved within the cylinders 16.
Piston section 17 is supported against said upper end wall 11 by
means of a spring device 19. The spring device 19 urges the pistons
18 into the lower end position. By hydraulic pressure within the
cylinders 16, the pistons 18 will be pushed upward against the
effect of spring 19.
[0016] Piston section 17 has an annular shape. A tensioning bolt
20, comprising a shaft portion 21 and a coupling portion 22, is
arranged to extend coaxially through the piston section. Said
coupling portion 22 is arranged internally of support tube 12 and
includes an axial threaded bore 23 terminating at an end face
24.
[0017] Further illustrated in FIG. 2 is the screw connection 30.
The screw connection comprises a threaded bolt 31 with an outer
thread, and a nut 32 screwed onto said outer thread and provided
with an underlying washer 32a. Said threaded bolt 31 is a component
part of the workpiece on which the support tube 12 is supported by
its end face 25. The hydraulic tensioning device serves for axially
stretching the threaded bolt 31 in order to allow the nut 32 to be
rotated without larger resistance. This rotating movement can be
performed via the gear transmission 14 or by manual engagement of
the nut via slits in support tube 12. The support tube is provided
with a wrench ring 33 whose inner contour is adapted to the
hexagonal contour of nut 32 and which can be rotated by
transmission gear 14. Said wrench ring 33 is rotatable relative to
support tube 12. In this manner, nut 32 can be rotated while the
threaded bolt 31 remains fixed.
[0018] For the tensioning process, it is important that a specific
minimum screw-in depth of threaded bolt 31 into said threaded bore
23 is maintained. This screw-in depth ET normally has to be at
least equal to D, with D being the thread diameter of the threaded
bolt. For measurement of the screw-in depth ET, a depth measurement
device 35 is provided. The latter comprises a measurement rod 36
extending through an axial channel 37 of shaft portion 21. Said
measurement rod 36 extends into threaded bore 23. Its end forms an
abutment portion 38 for abutment against the end 39 of threaded
bolt 31. The opposite end is provided with a marking 40, e.g. a
color marking, which can be moved out of the end wall 11 of the
casing and will then be visible from outside.
[0019] Arranged internally of tensioning bolt 20 is a spring 42
which by one of its ends is supported on the tensioning bolt and by
its other end engages the measurement rod 36 and presses the same
toward the threaded bolt 31.
[0020] When using the screw tensioning device, one will first screw
the nut 32 loosely onto the threaded bolt 31. Then, the screw
tensioning device will be placed onto the screw connection 30 and
be rotated about its axis, thus screwing the tensioning bolt 20
onto the threaded portion of threaded bolt 31. With the aid of the
depth measurement device 35, it will be detected whether the
projecting length U of the threaded bolt beyond the nut 32 is
sufficiently large for pressing the marking 40 out from the casing.
The depth measurement device 35 is encapsulated within the screw
tensioning device and thus accommodated in a well-protected manner,
preventing it from exposure to external influences. In the process
of screwing the screw tensioning device onto the threaded bolt 31,
the measurement rod 36 is pressed upward against the pressure of
spring 42 so that the marking 40, which in the unused state is sunk
within the casing, will be moved outward and thus become visible.
Thereby, the user is informed that the projecting length of the
threaded bolt 31 beyond nut 32 is sufficient to allow for the
pressurization of cylinder member 15.
[0021] In the present embodiment, the marking 40 will give an
optical signal. Alternatively or additionally, it can be provided,
according to a preferred embodiment of the invention, that an
acoustic acceptance signal is generated when the measurement rod 36
is in the acceptable range. The user will then not need to focus
his/her gaze to the tensioning device.
* * * * *