• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention describes an improved sensorized nut (1) comprising: a hexagonal proximal portion (2) having a hexagonal cross section and comprising a threaded central longitudinal hole (21); a cylindrical distal portion (3) having a circular cross section, where the cylindrical distal portion (3) is longitudinally adjacent to the hexagonal portion (2) so that both form a single piece, and where the cylindrical distal portion (3) it comprises a central longitudinal hole (31) devoid of thread whose diameter is equal to or greater than a diameter of the central longitudinal threaded hole (21) of the hexagonal portion (2); and at least one tension sensor (4) attached to a surface of the cylindrical portion (3) at a position spaced from a distal end of said cylindrical distal portion (3). (Machine-translation by Google Translate, not legally binding)
    公开号:ES2841453A1
    申请号:ES202130424
    申请日:2021-05-10
    公开日:2021-07-08
    发明作者:Diez Alejandro Anda；Hernandez Jaime Fernandez
    申请人:Inalia Innovacion Y Desarrollo S L；
    IPC主号:
    专利说明:

    [0003] OBJECT OF THE INVENTION
    [0005] The object of the present invention is a sensorized nut whose design makes it possible to improve the precision of the measurement.
    [0007] BACKGROUND OF THE INVENTION
    [0009] Bolted connections are universally extended in very diverse fields for the fixing of some elements to others. In some contexts, it is important to know the behavior of these bolted joints, especially the value of the preload and its evolution over time. As an example, this aspect is key in the start-up of a generator, since a single unit can have more than 1500 critical screws. An incorrect preload during assembly or a loss of preload during the work cycle can lead to premature failure, with significant repair and downtime costs.
    [0011] A known way of obtaining information about the load in a bolted joint is the use of sensorized nuts that are provided with sensors such as strain gauges or the like. These sensors can be arranged embedded in the nut itself or fixed to its outer surface, so that they measure the deformation of the nut caused by the load to which it is subjected.
    [0013] A drawback of this scheme is that it is sensitive to the tolerances of the nut and the part to which it is attached. Indeed, the manufacturing process of the nut causes that the support faces are not completely flat, but rather have a certain taper. Similarly, the surface of the part on which the nut rests may also not be perfectly flat due to tolerances both in manufacturing and in the assembly itself. As a consequence, the support of the nut on the part does not occur on the entire surface of the nut, but the contact between nut and part takes place in certain areas or points. For this reason, in the portion of the nut closest to the surface of support, local effects are produced that prevent a precise measurement of the tensions. In certain cases, these local effects can cause errors of up to 50% in the measurement of the stresses to which the nut is subjected.
    [0015] In short, in this field there is a need for sensorized nuts that are more insensitive to this type of local effects in order to provide a more accurate measurement of stresses.
    [0017] DESCRIPTION OF THE INVENTION
    [0019] The present invention describes a sensorized nut that solves the above problems thanks to the fact that it comprises a threaded hexagonal portion followed by a sensorized cylindrical portion intended to rest on the part in question, where said cylindrical portion lacks a thread. This cylindrical portion makes it possible to separate the area of contact with the part, where local effects occur, from the position in which the tension sensors are arranged. Thus, by moving the measurement zone away from the zone in which local effects occur, the precision and repeatability of the measured voltages is greatly improved.
    [0021] In this document, the term "tension sensors" is used to refer to any type of sensor capable of measuring, directly or indirectly, the tension to which the nut is subjected. That is, this term encompasses strain sensors, elongation or contraction sensors, and in general any sensor from which the stress on the nut can be obtained. Although the term "stress" is used generally in this document, it is intended to also encompass other related physical variables that are commonly used interchangeably in this field, or that can be easily deduced from each other, such as strain. or any other.
    [0023] In this document, the term 'next!' refers to one side or end of an element that is located in the closest position to the user according to its natural position of use. Similarly, the term 'dista!' refers to the side or end of said element located in the position furthest from the user in its most natural position of use. In this context, the "user" would be the operator in charge of screwing the nut.
    [0025] In this document, the terms 'longitudinal', 'tangential' and 'radial' are interpreted with reference to a cylindrical reference system whose longitudinal axis coincides with the longitudinal axis of the nut itself. Thus, the longitudinal direction coincides with the proximal-distal direction and the tangential and radial directions are contained in a plane perpendicular to said proximal-distal direction.
    [0027] The present invention describes a sensorized nut that fundamentally comprises three elements: a hexagonal proximal portion, a sensorized cylindrical distal portion, and at least one tension sensor. Each of these parts is described in more detail below.
    [0029] a) Hexagonal proximal portion
    [0031] It is a proximal portion that has a prismatic shape with a hexagonal cross section, and that comprises a threaded central longitudinal hole intended to receive a screw, bolt or the like for fixing the nut to a certain piece. That is, the hexagonal proximal portion has a structure similar to that of a conventional nut.
    [0033] b) Cylindrical distal portion
    [0035] The cylindrical distal portion has a circular cross section and is longitudinally adjacent to the hexagonal portion so that both form a single piece. Furthermore, the cylindrical portion comprises a threadless central longitudinal hole whose diameter is equal to or greater than a diameter of the threaded central longitudinal hole of the hexagonal portion. That is, the hexagonal proximal portion has a structure similar to that of a conventional socket.
    [0037] Ultimately, the nut of the invention is formed by a single piece provided with two geometrically different shaped bodies: hexagonal proximal portion and cylindrical distal portion. The longitudinal hole of the nut as a whole will have two differentiated sections, a threaded proximal section intended to be threaded through a screw or similar, followed by a distal section, whose diameter is equal to or greater, and lacks a thread.
    [0039] c) Voltage sensor
    [0040] The nut of the invention further comprises at least one tension sensor attached to a surface, preferably an outer surface, of the cylindrical portion at a position spaced from a distal end of said cylindrical distal portion.
    [0042] This tension sensor, for example a strain gauge, can be oriented in the longitudinal direction, in the tangential direction, or in a direction intermediate between the longitudinal direction and the tangential direction. When it comes to several sensors, they can be located in several of these directions. The orientation of the voltage sensors is chosen according to each particular application depending on the voltages to be obtained. The sensors can furthermore be arranged in uniformly spaced angular positions, such as two sensors or groups of sensors in diametrically opposite positions, or four sensors or groups of sensors in positions that form 90 ° to each other.
    [0044] In a conventional way, the sensors can be connected to a Wheatstone bridge from which it is possible to obtain the voltage signal insensitive to the measurement temperature.
    [0046] The inventors of the present application have found that this configuration provides more repeatable and accurate stress measurements. Indeed, firstly, the arrangement of the cylindrical distal portion provides a measuring zone whose tensions are not affected by the tightening of the screw in question, as occurs with a conventional nut. Second, by reducing the surface of the distal bearing face of the nut on the part in question relative to a conventional nut, local effects on stresses are reduced. Thanks to all this, the measurements obtained by the sensors are more reliable.
    [0048] Various tests carried out by the inventors of the present application show that, for best results, it is preferable that a length of the cylindrical distal portion is greater than between 1.0 and 1.5, more preferably between 1.2 and 1, 3, and even more preferably about 1.25, times the diameter of the threaded longitudinal hole of the hexagonal portion, that is, the metric of the nut.
    [0050] Indeed, Fig. 3 shows the error of the preload measurement under very unfavorable support conditions, as a function of the position of the measurement points (expressed as a dimensionless parameter as a function of the metric). As you can see, it is necessary a minimum length of between 70% and 80% of the metric so that the error is on the order of -5%. You can also see how it is necessary to move the measurement points away from the hexagonal area by a length of at least 20% of the metric. In addition, for the stability of the measurement and to facilitate the manufacturing process, the measurement zone must have an amplitude of at least 0.25 times the metric. All of this gives a total minimum length of about 1.25 times the metric
    [0052] According to another particularly preferred embodiment, the tension sensor is spaced from the distal end of the cylindrical portion a distance of between 0.55 and 0.75 times the length of said cylindrical distal portion.
    [0054] Using a graph similar to the previous one, Fig. 4 again shows the error of the preload measurement under very unfavorable support conditions, as a function of the position of the measurement points (expressed in this case as a dimensionless parameter as a function of cylindrical distal length). As can be seen, the measurement point where the error is minimized is between 55% and 75% of the total length.
    [0056] BRIEF DESCRIPTION OF THE DRAWINGS
    [0058] Fig. 1 shows a perspective view of an example of a nut according to the present invention.
    [0060] Figs. 2a and 2b respectively show a section of the nut of Fig. 1 along a longitudinal plane and a cross section of the cylindrical portion along the plane AA 'shown in Fig.2a.
    [0062] Fig. 3 shows the error as a function of the point of measurement with point support in two areas, where the position is dimensionless as a function of the metric, where the position of the measurement area has been marked.
    [0064] Fig. 4 shows the error as a function of the point of measurement with point support in two areas, where the position is dimensionless as a function of the length of the cylindrical part, where the measurement area has been marked.
    [0066] Fig. 5 shows a perspective view of a simulation of the stresses in the nut when it is supported non-uniformly on a part.
    [0067] PREFERRED EMBODIMENT OF THE INVENTION
    [0069] An example of a nut (1) according to the present invention is described below with reference to the attached figures.
    [0071] As can be seen in Figs. 1 and 2, the nut (1) is formed by a single piece that comprises two bodies of geometrically differentiated shapes. On a proximal side of the nut (1) is a hexagonal proximal portion (2), while on the distal side of the nut (1) there is a cylindrical distal portion (3). The hexagonal proximal portion (2) has a hexagonal cross section and is provided with a central longitudinal hole (21) intended to receive a fixation screw. For its part, the cylindrical distal portion (3) has a cylindrical cross section provided with a central longitudinal hole (31) devoid of thread and whose diameter is greater than the diameter of the central longitudinal hole (21) of the hexagonal proximal portion (2 ). Thus, when a screw is fixed to the nut (1) of the invention, the mechanical coupling between the two only occurs in the proximal hexagonal portion (2). The cylindrical distal portion (3) is not affected by stresses caused by tightening the screw. Furthermore, in this example the cylindrical distal portion (3) has a length (L) of approximately 1.25 times the diameter of the central longitudinal hole (21) of the hexagonal proximal portion (2).
    [0073] The nut (1) further comprises four sensors (4), in this example strain gauges arranged in a longitudinal direction of the nut (1) itself. In this example, the sensors (4) are separated from the distal end of the cylindrical distal portion (3) a distance (D) of approximately between 0.55 and 0.75 times the length (L) of said cylindrical distal portion (3 ).
    [0075] Fig. 5 shows a simulation of the stresses to which the nut (1) of the invention is subjected when the distal end of the cylindrical distal portion (3) rests on a non-uniform surface of a piece, so that the Support occurs essentially at two diametrically opposite points of the cylindrical distal portion (3). As can be seen, the magnitude of the stress disturbances are located in the area adjacent to said support end, and are substantially reduced as we move away from said end. The inventors of the present application have determined that, for a length of the cylindrical distal portion (3) of between 1.0 and 1.5 of the metric, once the separation reaches approximately between 55% and 75% of the bliss length (L) cylindrical distal portion (3), said disturbances have been significantly reduced and it is possible to obtain reliable stress values through the sensors (4).
    权利要求:
    Claims (7)
    [1]
    1. Improved sensorized nut (1), characterized by comprising
    - a hexagonal proximal portion (2) having a hexagonal cross section and comprising a threaded central longitudinal hole (21);
    - a cylindrical distal portion (3) that has a circular cross section, where the cylindrical distal portion (3) is longitudinally adjacent to the hexagonal portion (2) so that both form a single piece, and where the cylindrical distal portion (3 ) comprises a central longitudinal hole (31) devoid of thread whose diameter is equal to or greater than a diameter of the threaded central longitudinal hole (21) of the hexagonal portion (2); Y
    - at least one tension sensor (4) fixed to a surface of the cylindrical portion (3) in a position spaced from a distal end of said cylindrical distal portion (3).
    [2]
    2. Improved sensorized nut (1) according to claim 1, wherein a length (L) of the cylindrical distal portion (3) is greater than between 1.0 and 1.5 times the diameter of the threaded longitudinal hole (21) of the hexagonal portion (2).
    [3]
    3. Improved sensorized nut (1) according to claim 2, wherein the length (L) of the cylindrical distal portion (3) is greater than between 1.2 and 1.3 times the diameter of the threaded longitudinal hole (21) of the hexagonal portion (2).
    [4]
    4. Improved sensorized nut (1) according to claim 3, wherein the length (L) of the cylindrical distal portion (3) is greater than essentially 1.25 times the diameter of the threaded longitudinal hole (21) of the hexagonal portion (2).
    [5]
    5. Improved sensorized nut (1) according to any of the preceding claims, wherein the tension sensor (4) is separated from the distal end of the cylindrical portion (3) by a distance (D) of between 0.55 and 0, 75 times the length (L) of said cylindrical distal portion (3).
    [6]
    6. Improved sensorized nut (1) according to any of the preceding claims, wherein the tension sensor (4) is fixed to an outer surface of the cylindrical portion (3).
    [7]
    7. Improved sensorized nut (1) according to any of the claims above, where the tension sensor (4) is a strain gauge.
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    同族专利:
    公开号 | 公开日
    ES2841453B2|2021-09-01|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4164164A|1976-07-13|1979-08-14|Trungold Emanuel H|Bolt tension indicating means|
    US20100054891A1|2008-08-27|2010-03-04|Asahi Electric Works, Ltd.|Fastening apparatus and system for detecting axial force thereof|
    US20140283617A1|2013-03-25|2014-09-25|Kabo Tool Company|Threaded member capable of detecting tension|
    US20150147138A1|2013-11-27|2015-05-28|Kabo Tool Company|Nut|
    WO2021022311A1|2019-08-04|2021-02-11|Revotec Zt Gmbh|Screw nut|
    法律状态:
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    申请号 | 申请日 | 专利标题
    ES202130424A|ES2841453B2|2021-05-10|2021-05-10|IMPROVED SENSORIZED NUT|ES202130424A| ES2841453B2|2021-05-10|2021-05-10|IMPROVED SENSORIZED NUT|
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