Patent Application
20240042628
The present invention relates generally to an apparatus for delivering a laser beam from a stationary end to a movable end and, more particularly, an apparatus comprising a self-balancing articulated arm for delivering laser beam form a stationary end to a movable end.
A beam delivery system is a device for transmitting a laser beam from its source to a laser head that projects the beam to a workpiece. Optical fibers are generally a preferred option for beam delivery because of their flexibility. This flexibility is especially beneficial for applications where the laser head needs to move. However, optical fibers cannot transmit a laser beam with a wavelength longer than 2600 nanometers due to high absorption rate of fibers. CO2 laser is an example of laser that cannot be delivered by optical fibers. Instead, CO2 laser is generally delivered by reflective mirrors that are often encapsulated in tubes.
Additionally, many applications of CO2 laser, such as welding, require the laser head to be moved by an automated machine such as a robot arm around a workpiece. Such applications generally require the laser head be capable of six degrees of freedom of movement to cover the entire surface of the workpiece. This adds another level of complexity to beam delivery of CO2 laser because the mirror-based delivery approach shall avoid restricting motion of the robotic arm. To that end, CO2 laser is generally delivered by the so-called articulated arm mechanism. An articulated beam delivery system for CO2 laser comprises a set of tubes that are connected one to another by rotatable joints or couplers and mirrors that are installed at joints or couplers to direct a laser beam from one tube to another tube.
When the laser head is carried and moved by an automated machine such as a robot arm, the corresponding articulated beam delivery system needs to behavior as a passive arm that moves with a robot arm. Since it is passive, it must be properly suspended to avoid limiting the robot arm's motion and to prevent colliding with the robot arm. One common mechanism for suspending articulated beam delivery systems involves using a tool balancer to provide suspension from a higher position. This works well in many applications, but it requires a structure or a supporting point above the system to attach the balancer. Therefore, this may not be suitable if a compact design is desired or if there is insufficient space above the system.
Another category of mechanisms for suspending articulated beam delivery systems uses either a counterweight or gas springs in a lever configuration. One example (U.S. Pat. No. 4,473,074) disclosed in prior art employs a counterweight to balance a structure to support an articulated beam delivery system in which the movable end is manually guided by a human operator. Another example (U.S. Pat. No. 7,951,139) disclosed in prior art provides a lever mechanism, which is supported by a gas spring, for suspending an articulated delivery system.
The solutions provided in these disclosures are small scale and unable to support heavy articulated beam delivery systems. Besides, these mechanisms overlooked the need to reduce the bending load on the beam delivery structure. For application involving high-power laser, the articulated beam delivery systems tend to be heavy and large, and minimizing the bending load on the delivery structure is critical to maintaining beam alignment. In short, the articulated beam delivery systems disclosed in prior art are inadequate in terms of their capability of reducing bending load, and there is a need for an improved mechanism for delivering high-power laser and suspending articulated delivery systems.
The present disclosure provides an articulated beam delivery system with a compact, flexible, and strong suspension mechanism. The present system is a self-balancing structure, and it is designed to minimize the deflection of its structures. The present articulated delivery system and its suspension structure form a four-bar parallelogram mechanism that is balanced by a gas spring. The gas spring connects a top linkage and a fixed linkage of the parallelogram to make it self-balanced. The lower linkage of this mechanism is a hollow tube for a laser beam to pass through. Mirrors inside joints at both ends of this tube deflect the laser beam from or to connecting tubes. The weight of the hollow tube is borne by the top linkage; therefore, it is less likely to deflect under its own weight or the weight of other members of the system. This helps greatly for preventing misalignment between internal mirrors, thus allowing for long-term operation of the system without the need to realign of the mirrors frequently.
Embodiments will now be described, by way of example only, with reference to the drawings, in which:
Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. The drawings are not necessarily to scale. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.
As used herein, the terms, “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in this specification including claims, the terms, “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps, or components.
As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein.
As used herein, the terms “about” and “approximately”, when used in conjunction with ranges of dimensions of particles, compositions of mixtures or other physical properties or characteristics, are meant to cover slight variations that may exist in the upper and lower limits of the ranges of dimensions so as to not exclude embodiments where on average most of the dimensions are satisfied but where statistically dimensions may exist outside this region. It is not the intention to exclude embodiments such as these from the present disclosure.
The present disclosure relates to an articulated beam delivery system and its suspension structure for transmitting a laser beam from a stationary source to a movable end. As required, preferred embodiments of the invention will be disclosed, by way of examples only, with reference to drawings. It should be understood that the invention can be embodied in many various and alternative forms. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the embodiments described herein. Also, the description is not to be considered as limiting the scope of the embodiments described herein.
The structure of the articulated beam delivery system and its suspension structure will first be described.
Referring to
Said tube 1, linkage 17, linkage 8, and linkage 16 form a parallelogram mechanism that is supported by spring 14. Linkage 16 bears the weight of tubes 1, 2, and 4. The spring 14 is sized such that it bears the total weight of the articulated arm including linkage 16. The spring 14 is also sized such that the stroke of the spring 14 allows for a desired range of rotation of tube 1 around the longitudinal axis of tube 11.
In a preferred embodiment, said spring 14 is a gas spring or an air spring.
Said articulated arm may further comprise a few additional articulated elements connecting to tube 1 for providing six or higher degrees of freedom for the end of said articulated arm. The configuration of these additional articulated elements is very similar to articulated arms disclosed in prior art. Continuing with reference to
The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms.
Provisional application No. 63/233,725, filled on Aug. 16, 2021.
