The invention relates to a positioning device for a positioning system for positioning a first object in relation to a second object. Furthermore, the invention also relates to a positioning system comprising such a positioning device.
When placing two objects, e.g. a working table or a base plate on a milling machine table, it is important to be able to accurately position these two objects in relation to each other in order to be able to use e.g. a milling machine reference system for an object arranged on the working table. Before the 1960:s a majority of the machining and measuring within the engineering industry took place by making relative measurements using e.g. micrometer calipers, sliding calipers and templates for dimensional accuracy. Drawings were produced manually to fit these manufacturing methods. The precision depended more on the skill of the workers and operators of the machines than the stability and the lack of freedom of play of the machines. When numerically controlled machines for the production appeared on the market, the manufacturing methods began to be more and more automated and today the production is to a large extent more or less automated using e.g. CNC-controlled multioperation machines.
During the above development of the production processes, the manufacturers of the machines have also minimized the previous problems of the machines being able to turn the input instructions to corresponding output process steps without accuracy problems. This is also the case regarding problems with temperature stability, freedom of play and elastic deformation. The above enables for metalworking equipment to move to completely digitalized production by absolute coordinated originating from a given zero offset point using digital measurement and control systems and automated tool changing systems in the machines.
A reference system commonly used in e.g. machine shops is the Cartesian coordinate system having XYZ-directions. When talking about accurate positioning in machine shops and e.g. turning, milling and drilling, tolerances of 0.01 mm-1 μm are considered “accurate”, whereas tolerances smaller than 1 μm are often difficult to use in production applications as such tolerances often are difficult to measure in real production. Whereas it is relatively easy to achieve and maintain high tolerances in a laboratory environment, temperature changes and pollution as well as wear are issues that have to be handled in real production equipment whether it is manually operated or automated.
An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.
Another objective of embodiments of the invention is to provide a solution with improved accuracy in the XY-plane positioning of a first object in relation to a second object.
The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.
According to a first aspect of the invention, the above mentioned and other objectives are achieved with a positioning device for a system for positioning a first object in relation to a second object in a XY-reference system, the positioning device comprising:
The positioning device may also be denoted a zero-positioning device or a positioning device. The XY-reference system may also mean the XY-plane of a Cartesian coordinate system. The deflection of the first spring portion and the second spring portion may occur when a radial force is acting on the spring arrangement due to a press fit mounting. The deflection may also be understood as a deformation. The first XY-reference means may be denoted first XY-positioning means and the second XY-reference means may be denoted second XY-positioning means.
An advantage of the positioning device according to the first aspect is that the accuracy of the positioning of the first object in relation to the second object in the XY-plane is improved compared to conventional solutions.
In an implementation form of a positioning device according to the first aspect,
Hence, the deflection of the first spring portion and the second spring portion is balanced for controlled deflection of the spring arrangement.
In an implementation form of a positioning device according to the first aspect,
Hence, the conical inner surface of the first XY-reference means may abut/press against the conical outer surface of the second XY-reference means in operation.
In an implementation form of a positioning device according to the first aspect,
In an implementation form of a positioning device according to the first aspect,
In an implementation form of a positioning device according to the first aspect, the spring arrangement comprises
In an implementation form of a positioning device according to the first aspect, the spring arrangement comprises
In an implementation form of a positioning device according to the first aspect,
In an implementation form of a positioning device according to the first aspect, the spring arrangement comprises a spring coupling portion configured to serially couple the first spring portion and the second spring portion.
In an implementation form of a positioning device according to the first aspect, the spring coupling portion comprises a groove.
In an implementation form of a positioning device according to the first aspect, the groove is a punched groove.
In an implementation form of a positioning device according to the first aspect, the groove is circularly arranged with a constant radius around a center axis of the positioning device.
In an implementation form of a positioning device according to the first aspect, the spring arrangement is formed from a single sheet metal piece with constant thickness.
In an implementation form of a positioning device according to the first aspect, the second object is configured to support the first object in the positive Z-direction in operation.
According to a second aspect of the invention, the above mentioned and other objectives are achieved with a system for positioning a first object in relation to a second object in a XY-reference system, the system comprising at least one positioning device according to any one of the preceding claims.
Further applications and advantages of the embodiments of the invention will be apparent from the following detailed description.
The appended drawings are intended to clarify and explain different embodiments of the invention, in which:
Furthermore, the first object 302 may e.g. be a working table, a base plate, a fixture, a pallet, a tool, etc., and the second object 304 may e.g. be a machine table, a machine base, etc. but are not limited thereto. The first object 302 may comprise a downward directed cavity in which cavity the first XY-reference means 102 may be fixed to as shown in
In embodiments of the invention, the second object 304 is configured to support the first object 302 in the positive Z-direction in operation as shown in
In embodiments of the invention, the first spring portion 132 is configured to deflect in the positive Z-direction +Z with a first amount, and the second spring portion 134 is configured to deflect in the negative Z-direction −Z with a second amount. The first amount is substantially the same as the second amount for balancing the deflection of the first spring portion 132 and the second spring portion, respectively, for controlled total deflection of the spring arrangement 130 of the positioning device 100.
When the first XY-reference means 102 is mounted, e.g. by press fit in which a high radial force will act on the first XY-reference means 102, the first XY-reference means 102 may deform in a non-controlled manner so that the positioning of the first object in relation to the second object is not accurate enough for precision applications. However, by having a spring arrangement 130 according to embodiments of the invention the deformation or deflection of the spring arrangement 130 may be controlled. This means improved accuracy.
Furthermore, the positioning device 100 may comprise means for attaching/fastening the positioning device 100 to the first object 302 and the second object 304, respectively. In the disclosed embodiment, the positioning device 100 comprises first attachment means 120 for attaching to the first object 302 and second attachment means 118 for attaching to the second object 306. The first attachment means 120 and the second attachment means 118 may e.g. be first h1 and second h2 through holes of different diameters arranged inside a body 106, the latter having an axial extension and e.g. having cylindrical symmetry and further a section that is encircled by a taper of the second XY-reference means 104. The body may be made of a suitable material such as a metal. The first h1 and second h2 through holes may comprise inner threads configured to receive outer threads of bolts (not shown) of the first 302 and second objects 304, respectively. Thereby, a secure attachment or fastening of the positioning device 100 to the first 302 and second objects 304, respectively, may be achieved. As also illustrated herein, the positioning device 100 may comprises a clearance 116 also in the form of a through hole h3 having a diameter larger than the diameter of the through holes of the first 120 and second 118 attachment means. Thereby, the risk of the positioning device 100 being misaligned due to radial forces acting on the positioning device 100 so as to distort the positioning accuracy in the XY-plane is reduced or minimized. This is especially the case when the positioning device 100 is to be mounted in the system 200.
As further disclosed in
As disclosed, in embodiments of the invention, the spring arrangement 130 comprises a rim portion 136 which is serially coupled to the first spring portion 132. The rim portion 136 may be of the type stiff rim and being configured to press against the taper of the second XY-reference means 104 in operation as shown in
As previously mentioned, the first spring portion 132 is serially coupled to the second spring portion 134, or vice versa. This may be achieved by the use of a spring coupling portion 140 that is configured to serially couple the first spring portion 132 and the second spring portion 134 to each other. The spring coupling portion 140 may be considered as a spring hinge mechanically coupling independent springs but also demark different spring portions from each other. It is noted that the spring arrangement 130 herein may comprise any number of spring coupling portions coupling any number of first 132 and second 134 spring portions which means that the invention is not limited to a single spring coupling portion coupling a single first spring portion and a single second spring portion.
In further embodiments of the invention, the spring coupling portion 140 comprises of a groove which may be circularly arranged with a constant radius around a center axis A of the positioning device 100 as shown in 3a, 3b and 4. It has been noted that a groove works perfectly well in acting as a spring coupling portion 140 for many applications. However, the spring coupling portion 140 may be realized with other means having the same function as previously described.
When the spring coupling portion 140 comprises of a groove economic advantages is achievable when manufacturing the spring arrangement 130 herein. For example, the groove may be a punched groove which is inexpensive to produce. In embodiments of the invention, the spring arrangement 130 is formed from a single sheet metal piece with constant thickness, and the single sheet metal piece may be punched or stamped in a single manufacturing step using a dedicated tool so as to produce the spring arrangement 130. In this way both high accuracy in positioning and low cost at production of the positioning device 100 is possible.
For providing even deeper understanding of embodiments of the invention in respect of the spring arrangement 130, some numbers are given which are exemplary only and are dependent on the application of the positioning device 100 and positioning system 200. With reference to
Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.
Number | Date | Country | Kind |
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20203059.9 | Oct 2020 | EP | regional |
2051226-5 | Oct 2020 | SE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/078054 | 10/11/2021 | WO |