JPH0567834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bellows for protecting moving parts of machines, devices, etc.

[Prior Art] Some moving parts of machines and devices have parts that must be protected from the external environment. For example, in the case of a robot hand, a precise load detection device is attached to the appropriate position of the hand in order to optimally control the hand according to the intended use. Since the detected value of this load detection device is adversely affected by physical shock or changes in humidity, etc., it is necessary to protect it from the external environment with appropriate members. Traditionally, such protection has been achieved using accordion-like bellows. Hereinafter, this bellows will be explained using figures.

Figures 6a-c are side views of the bellows. In the figure, 1 is an accordion-shaped bellows formed of a thin metal plate, 1a is a convex ridgeline of the bellows 1, and 1b is a concave ridgeline of the bellows 1. Reference numerals 3 and 4 are connecting portions at both ends of the bellows 1, which are connected to both sides of the load transmitting device when protecting the load detecting device.
Here, if the coordinate axes are defined as shown (the Y axis is a direction perpendicular to the paper surface), it is clear that the bellows 1 can be expanded and contracted in the Z axis direction. Further, as shown in FIG. 6b, it can be deformed as shown in the figure in response to a moment about the Y-axis, and accordingly, it can also be deformed in the same manner in response to a moment about the X-axis. Furthermore, as shown in FIG. 6c, it can be deformed as shown in the figure in response to a force in the X-axis direction, and accordingly, it can also be deformed in the same manner in response to a force in the Y-axis direction.

[Problems to be Solved by the Invention] In this way, the conventional bellows 1 described above has
Since it is deformable in response to forces in the axial and Z-axis directions, as well as moments around the X- and Y-axes,
Displacement along three axes and twisting around two axes are free. However, the bellows 1 cannot be deformed by a moment about the Z-axis, and a large restraint force exists against twisting about the axis. By the way, load detection devices usually have X-axis, Y-axis,
It is often required to detect all loads on the shaft, and to meet this requirement, a protective structure with six degrees of freedom is required that does not have any restraining force against twisting around the shaft. be. However, conventionally, a protection mechanism having six degrees of freedom has not been provided, and a load detection device that detects loads on six axes has not been completely protected.

An object of the present invention is to provide a bellows having six degrees of freedom with extremely small restraining force against all displacements and torsions.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a bellows-shaped first structure that surrounds one of the coordinate axes and has uneven ridge lines formed alternately in parallel to each other. a second bellows that surrounds the one axis, has a predetermined inclination with respect to the axis, and is formed with alternately continuous uneven ridgelines at both ends in the axial direction; and the first bellows. and a connecting part that connects the second bellows, and a triangle formed by the intersection of two adjacent ridge lines in the second bellows and the respective terminal ends of the two ridge lines on the side opposite to this intersection. , characterized in that, when this triangle is projected in the axial direction, a perpendicular line drawn from the intersection point to an extension line connecting each of the terminal ends is substantially tangent to a circle including the intersection point and each of the terminal ends. .

[Operation] The first bellows has almost no restraining force against displacement in the axial direction of the three coordinate axes and rotational displacement around two axes other than the axis surrounded by the first bellows and the second bellows. . Further, the second bellows has almost no restraining force against rotational displacement about the axis surrounded by the first bellows and the second bellows. That is, when torsion is applied around the axis of the shaft surrounded by the first bellows and the second bellows, the end of the ridgeline of the second bellows bends along the line between the adjacent end, and at the same time The intersection points are displaced in the tangential direction of the circle. in this case,
Since the torsion acts along the circle, the direction of displacement at the above-mentioned intersection coincides with the direction in which the torsion acts, and as a result, the restraining force against the torsion becomes extremely small.

[Examples] The present invention will be described below based on illustrated examples.

FIG. 1 is a side view of a bellows according to a first embodiment of the invention. In the figure, the same parts as those shown in FIGS. 6a to 6c are given the same reference numerals. 5 is a torsion bellows formed of a thin metal plate; 5a is a convex ridgeline of the torsion bellows 5; and 5b is a concave ridgeline of the torsion bellows 5. Reference numeral 6 designates a ring-shaped connecting portion that connects the bellows 1 and the torsion bellows 5, and 7 represents a ring-shaped connecting portion that connects to one end of the load detection device. The structure of the torsion bellows 5 will be explained in more detail with reference to FIG.

FIG. 2 is a developed view of the torsion bellows. In the figure, parts that are the same as those shown in FIG. 1 are designated by the same reference numerals. The figure is a developed view of an arbitrary part of the torsion bellows 5 cut along a line AB parallel to the axis of the coordinate axes shown in FIG. In the figure, for ease of understanding, a plurality of upward arrows are attached to the convex ridge line 5a, and a plurality of downward arrows are attached to the concave ridge line 5b. Each ridgeline 5a is inclined at a predetermined angle with respect to the line AB (with respect to the Z axis),
Moreover, each ridgeline 5b is inclined at another predetermined angle. The ridge lines 5a and 5b are formed alternately, and are connected to each other at connecting portions 6 and 7 via inclined surfaces, which will be described later. 8, 8' indicate opposing inclined surfaces;
The slope 8 slopes upward from right to left in the figure.
The inclined surface 8' slopes upward from left to right in the figure. Therefore, at the line B-B, the inclined surface 8
The bottom portion of the inclined surface 8' also rises from right to left in the drawing, and the bottom portion of the inclined surface 8' along line A-A also rises from left to right in the drawing. By connecting the lines AB at both ends of such a developed view, the torsion bellows 5 shown in FIG. 1 is constructed.

Figures 3a and 3b are side views showing the operation of the torsion bellows. FIG. 3a shows the state of the torsion bellows 5 in which both ends of the developed view shown in FIG. 2 are simply connected. h is the distance between the lower end of the connecting part 3 and the upper end of the connecting part 7. This torsion bellows 5 has an X axis,
It exhibits an extremely large restraining force against displacement in the Y-axis and Z-axis directions, and against twisting around the X-axis and Y-axis.
However, the restraining force against twisting around the Z axis is extremely small.

FIG. 3b shows the deformation of the torsion bellows 5 when a moment shown by the arrow around the Z axis is applied to the torsion bellows 5. In this way, the torsion bellows 5 deforms in a constricted manner in response to the moment. At this time, the distance h between the connecting parts 3 and 7
is shortened to a slightly shorter distance h′.

Here, the reason why the torsion bellows 5 has a weak restraining force against twisting around the Z axis and easily undergoes the deformation shown in FIG. 3b will be discussed with reference to FIGS. 4a and 4b. Now, in Figure 3 a,
The point where one ridgeline 5a connects with the connecting part 3 is E, the point where this ridgeline 5a connects with the connecting part 7 is C, and the ridgeline 5b that is continuous with this ridgeline 5a and the connecting part 3 is the connecting part 7. Let D be the joining point. These points C, D, and E form the slope of triangle CDE.

If we focus only on this triangle CDE and view it from above in Figure 3a, its projection will be as shown in Figure 4a. In Fig. 4a, G indicates a circle including points C, D, and E, and F indicates the intersection of side CD and the perpendicular line drawn from point E to side CD. From the above explanation, the ridge lines 5a,
5b and the side CD are difficult to bend and therefore maintain a straight line, thereby keeping the triangle CDE flat.

As shown in FIG. 3b, when the torsion bellows 5 is twisted, the triangle CDE moves while bending at the side CD, and the point E moves on the perpendicular line EF. In this case, the perpendicular EF is the circle G (point E of each triangle) as shown in the figure.
is on this circle. ), the direction of movement of point E and the direction of movement of connecting part 3 match, so
Triangular CDE can move without resistance while remaining flat. And, since this is true for all the triangles constituting the torsion bellows 5, the torsion bellows 5 will eventually be torsionally deformed very easily.

FIG. 4b is a projection view when the triangle CDE has such a shape that the perpendicular line EF does not touch the circle G. In this case, when the torsion bellows 5 is twisted, the moving direction of the point E is different from the moving direction of the connecting portion 3, so the movement occurs while distorting the triangle CDE or the connecting portion 3. Triangle CDE or connection part 3
As a result, the torsion bellows 5 will not twist as easily as the one with the conditions shown in FIG. 4a.

From the above, in order to cause the torsion bellows 5 to be torsionally deformed very easily, each connecting portion 3,
It can be seen that it is necessary to form the above-mentioned triangle so that the perpendicular lines drawn from the term points of all the triangles connected by sides at 7 to the sides are approximately tangent to the circle connecting all the term points.

Here, we return to the description of the bellows of this embodiment shown in FIG. 1. The load detection device to be protected is enclosed inside the bellows 1, and both ends thereof are connected to the connecting parts 3 and 7. In this case, the torsion bellows 5 is connected in the state shown in FIG. 4a.
Now, for convenience of explanation, it is assumed that one end of the load detection device connected to the connecting portion 7 is fixed. When a load acts on the other end of the load detection device connected to the connection part 3, as described above, X of this load
With respect to forces in the axial, Y-axis, and Z-axis directions, and moments about the X- and Y-axes, the bellows 1 displaces or twists, so that the load transmission is not restricted in any way. Furthermore, when a moment about the Z-axis is applied, the torsion bellows 5 is twisted via the connecting portion 3, the bellows 1, and the connecting portion 6, so that the load transmission in this case is also not subject to any restrictions. In this case, Fig. 3b
As shown in FIG. 2, the distance in the Z-axis direction of the torsion bellows 5 is shortened, but this is absorbed by the extension of the bellows 1 in the Z-axis direction, so that no restriction occurs.

In this way, in this embodiment, since the bellows in the form of a bellows and the torsion bellows are connected, displacement in the three axial directions and twisting around the three axes are free (6 degrees of freedom), and all loads can be detected. The detection device can be completely protected from the external environment.

FIG. 5 is a partially cutaway side view of a bellows according to a second embodiment of the present invention. In the figure, the same parts as those shown in FIG. 1 are given the same reference numerals. In this embodiment, the torsion bellows 5 is housed within the bellows 1. Reference numeral 6' denotes a connecting part at the end of the bellows 1, and 6'' denotes a connecting part at the end of the torsion bellows 5. Reference numeral 9 denotes a connecting member that connects the connecting part 6' and the connecting part 6''. One end of the load detection device is connected to the connecting part 3, and the other end is connected to the connecting part 7. In this case, the main part of the load detection device is disposed inside the torsion bellows 5, and the main part and the connecting part 3 are connected, for example, by a rigid member passing outside the bellows 1. It is clear from the description of the first embodiment that six degrees of freedom are obtained between the connecting portion 3 and the connecting portion 7.

In this way, in this embodiment, the torsion bellows is housed within the bellows-shaped bellows and the two are connected, so that not only the same effect as the first embodiment is achieved, but also the overall structure is made smaller. be able to.

In addition, in the description of the above embodiment, the load detection device was exemplified as the object to be protected, but the object to be protected is not limited to this, and it goes without saying that other devices or members may be used. Further, the bellows and the torsion bellows can be made of various materials other than thin metal plates depending on the external environment. Furthermore, the torsion bellows may not be integrally constructed, but a separate elastic member may be used only at each ridgeline portion, and in this case, the material and thickness of the members for the other portions can be freely selected.

〔Effect of the invention〕

As described above, in the present invention, since the bellows in the form of an accordion and the torsion bellows are connected, it is free against all displacements and twists.
This allows the object to be protected to be completely protected from the external environment.

[Brief explanation of drawings]

Fig. 1 is a side view of the bellows according to the first embodiment of the present invention, Fig. 2 is a developed view of the torsion bellows shown in Fig. 1, and Figs. 3a and 3b are side views of the torsion bellows shown in Fig. 1. Figures 4a and 4b are operating principle diagrams of the torsion bellows shown in Figure 1, Figure 5 is a partially cutaway side view of the bellows according to the second embodiment of the present invention, and Figures 6a, b, c is a side view of a conventional bellows. 1... Bellows, 1a, 5a... Convex ridge line, 1
b, 5b...concave ridge line, 3, 6, 6', 6'', 7...
... Connecting portion, 8, 8'... Slope, 9... Connecting member.

Claims (1)

[Scope of Claims] 1. A first bellows in the shape of a bellows, which surrounds one of the coordinate axes and has concave and convex ridge lines formed in parallel with each other; a second plate having a predetermined inclination, and formed with alternately continuous uneven ridge lines at both ends in the axial direction;
and a connecting portion that connects the first bellows and the second bellows, the intersection of two adjacent ridge lines of the second bellows and the two adjacent ridge lines on the side opposite to this intersection. When a triangle formed by each terminal end of the ridge line is projected in the axial direction, a perpendicular line drawn from the intersection point to an extension line connecting each terminal end is approximately tangent to a circle including the intersection point and each terminal end. A bellows characterized by being formed as follows. 2. The bellows according to claim 1, wherein one of the first bellows and the second bellows is housed in the other.