Planar robot with parallel axes and fixed motors for a water jet cutter

A planar robot for cutting products, such as pieces of meat. The product is displaced along a conveyor or positioned onto a working table and is cut by a tool, preferably a water jet. The tool is held by a pair of arms. The arms have first extremities pivotally mounted on mobile bases. The arms also have second extremities pivotally connected to each other. An actuator displaces each of the mobile bases in order to control the position of the cutting tool in a plane above the conveyor or table.

FIELD OF THE INVENTION

The present invention relates to a planar robot. More particularly, it relates to a planar robot especially adapted for cutting products transported on a conveyor or positioned onto a working surface, such as a fixed table.

BACKGROUND OF THE INVENTION

In the prior art, there exist different types of systems for cutting products transported on a conveyor.

For example, Canadian patent no. 1,307,719 belonging to DSI discloses an apparatus and a method for automatic cutting food products. The apparatus comprises a conveyor on which the products to be cut are displaced. The apparatus also comprises means to determine the dimension of the products to be cut. The apparatus further comprises a cutting tool that can travel in a transverse manner with respect to the displacement of the conveyor.

Prior art systems are interesting but often have high inertias in the mechanisms required for the transverse cutting.

Prior art systems are also very difficult to clean.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a planar robot for use to cut products, which comprises a cutting mechanism that is mechanically simple having arms with shapes that allow them to cooperate in a closer manner.

More specifically, a first object of the invention as claimed hereinafter, is to provide a planar robot for cutting products, such as pieces of meat having various shapes, while said products are moved on a conveyor, which comprises(a) a support structure having an entrance and an exit;(b) a conveyor for transporting the products to be cut from the entrance to the exit of the conveyor, said conveyor having a first side and a second side opposite to the first side; and(c) at least one cutting module, each of said at least one cutting module comprising:(i) a first arm extending above the conveyor and comprising:a first extremity pivotally mounted on a first mobile base, the first mobile base being connected to the support structure on the first side of the conveyor; anda second extremity;(ii) a second arm extending above the conveyor and comprising:a first extremity pivotally mounted on a second mobile base, the second mobile base being connected to the support structure on the second side of the conveyor; anda second extremity pivotally connected to the second extremity of the first arm around a junction axis perpendicular to the conveyor;(iii) a cutting tool fixed on or near the junction axis for cutting the products transported on the conveyor;(iv) a first actuator connected to the first mobile base for displacing the first mobile base along a first axis generally parallel to the direction of transportation of the products on the conveyor;(v) a second actuator connected to the second mobile base for displacing the second mobile base along a second axis generally parallel to the first axis; and(vi) a control system for activating the first and second actuators;
the first actuator and the second actuator, when activated, transmitting linear movements respectively to the first mobile base and to the second mobile base for displacement of the cutting module in a two-dimensional plane above the conveyor for cutting the products while they are transported by the conveyor.

The expression “generally parallel” in paragraphs (iv) and (v) hereinabove, encompass positions that are exactly parallel as well as positions that may be slightly at angle with respect to each other.

A second object of the invention as claimed hereinafter is to provide a planar robot for cutting products positioned on a working surface, such as a fixed table, which comprises:(a) a support structure with a working surface on which the products to be cut are positioned, said working surface having a first side and a second side opposite to the first side; and(b) a cutting module comprising:(i) a first arm extending above the working surface and comprising:a first extremity pivotally mounted on a first mobile base, the first mobile base being connected to the support structure on the first side of the working surface; anda second extremity;(ii) a second arm extending above the working surface and comprising:a first extremity pivotally mounted on a second mobile base, the second mobile base being connected to the support structure on the second side of the working surface; anda second extremity pivotally connected to the second extremity of the first arm around a junction axis perpendicular to the working surface;(iii) a cutting tool fixed on or near the junction axis for cutting the products positioned on the working surface;(iv) a first actuator connected to the first mobile base for displacing said mobile base along a first axis generally parallel to the first side of the working surface;(v) a second actuator connected to the second mobile base for displacing the second mobile base along a second axis generally parallel to the second side of the working surface;(vi) a control system for activating the first and second actuators;
the first actuator and the second actuator when activated, transmitting linear movements respectively to the first mobile base and to the second mobile base for displacement of the cutting module in a two-dimensional plane above the working surface for cutting the products positioned on said working surface.

As may be appreciated, the planar robot according to the present invention has the following advantages.It is mechanically simple.Its motors are preferably fixed, which decreases substantially the inertia of the mechanism, decreases the loads on the components and eliminates fatigue damage inflicted to electrical wiring. Furthermore, the size and weight of the motors have no negative impact on the performance of the system.The shapes of the arms allow the different mechanisms to fit together much more closely.It is much more sanitary as compared to conventional systems, since its mechanical elements are disposed principally on each side of the working surface or conveyor. Moreover, the system comprises very few components that are difficult to clean.It has a very low mass in movement (inertia), which facilitates large acceleration required for cutting specific or difficult shapes.It offers a large work surface with respect to the cluttering of mechanisms.

A non-restrictive description of preferred embodiments of the invention will now be given with reference to the appended drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

The planar robot10for cutting products according to the preferred embodiment of the invention as shown inFIG. 1, comprises a support structure having an entrance and an exit.

The robot comprises a conveyor12extending within the support structure for transporting the products14to be cut from the entrance to the exit of the conveyor. As shown, the conveyor12has a first side16and a second side18opposite the first side16.

The robot also comprises at least one cutting module20. This cutting module20as it is illustrated, comprises a first generally L-shaped arm22extending above the conveyor12.

The first arm22comprises a first extremity24pivotally mounted on a first mobile base26, the first mobile base26being connected to the support structure on the first side16of the conveyor12. The first arm22comprises also a second extremity28.

The cutting module20comprises a second generally L-shaped arm30standing above the conveyor12. This second arm30comprises a first extremity32pivotally mounted on a second mobile base34, that is connected to the support structure on the second side18of the conveyor12.

The second extremity36of the second arm30is pivotally connected to the second extremity28of the first arm22around a junction axis38perpendicular to the conveyor.

The module also comprises a cutting tool40fixed on or near the junction axis38for cutting the products traveling on the conveyor12.

The module further comprises a first actuator42and a second actuator44connected respectively to the first mobile base26and the second mobile base34for displacement of the first mobile base26and the second mobile base34along axis parallel to the direction of transportation of the product14on the conveyor12.

The module also comprises a control system46for activating the first42and second actuator44. The actuators42,44when activated transmit a linear movement to the mobile bases26,34for displacement of the cutting module40in a two-dimensional plane above the conveyor12for cutting the products while they are transported on the conveyor12.

Preferably, the robot further comprises a detector48to collect information on the product14to be cut by the conveyor12. This detector48is connected to the control system46to transmit to the cutting module(s) information on the products14that are traveling.

Preferably, the first and second actuators42,44each comprise a worm screw50,52actuated by a motor. These worm screws50,52extend along the travel axis of the actuators42,44. The first extremity of each of the adjacent arms22,30is mounted on to the corresponding worm screw via a traveling nut54,56, which ensures displacement of the arm when the motor is activated.

In the illustrated embodiments, the arms22,30are of a same length. However, depending on the kind of products to be cut or their position on the conveyor, the arms could be of different lengths.

It is worth noting also that the above-mentioned worm screws could be replaced by a system of belts or rack and pinions or by any other types of mechanisms that would generate a linear movement to the mobile bases.

Preferably, each traveling nut54,56is connected through the mobile base26,34to a linear guide58,60.

Preferably also, the cutting tool40comprises a cutting head generating a cutting water jet. However, the cutting tool40could alternatively be a laser, an ultrasonic cutter or any other type of cutting tool.

In another preferred embodiment shown inFIGS. 6 to 9, the planar robot10comprises several cutting modules70,72,74,76,78serially positioned one after the other along the length of the conveyor12.

As aforesaid, the products to be cut can be food products, such as pieces of meat.FIG. 5given for illustration purposes, is a top plan view of a pork cutlet62and of the cutting trajectory64that must be followed to cut the fats66on one side of this cutlet.

As illustrated inFIGS. 3A to 3F, the control system controls the position of the cutting head by activation of the two worm screws52,54having parallel axis. As may be noticed, the worm screws50,52are independently activated by their respective motor.

The traveling nuts54,56convert the rotational movement of the worm screws into linear movement along axis #1and #2. The traveling nuts are supported by linear guides58,60. The arms22,30that are connected to the traveling nuts and are joined through a rotoidal joint having an axis perpendicular to the plane of the screws, may thus be given different angular positions which allow proper positioning of the cutting head in a two-dimensional plane (X, Y).

FIGS. 3A to 3Fand4illustrate examples of cutting trajectories that can be achieved by the control system.

At position3A, the product to be cut14enters the cutting zone, with the cutting head already positioned to start the cut. The two lateral axis move along the Y+ direction. The rotational velocity of the worm screw52causing a displacement along the axis #2is superior to that of the worm screw50causing a displacement along the axis #1. Consequently, the cutting head moves along the X+ Y+ direction.

At position3B, the rotational velocity of the worm screw50along axis #1exceeds the rotational speed of the worm screw52along axis #2. The cutting head therefore displaces itself along the X− Y+ direction.

At position3C, rotations of worm screws50and52are inverted. So, the traveling nuts travel towards Y− and the cutting head moves in the X− Y− direction.

At position3D, the displacement speed along axis #1is superior to that along axis #2. Consequently, the cutting head moves in the X+ Y− direction.

At position3E, the cutting head finishes its trajectory. Both axis #1and #2produce a displacement in the Y+ direction. The cutting head moves in the Y+ direction to position itself for the next cutting operation.

The cutting mechanism can be used with a conveyor in continuous movement or with a conveyor which stops movement during cutting of the product. Alternatively, the cutting mechanism could be used on a working support, such as a fixed table. The basic structure would be substantially the same as illustrated hereinabove the only difference being in that a table would be used instead of the illustrated conveyor12.