INCORPORATION BY REFERENCE

The present application claims benefit of Italian Patent Application No. 102018000003869, filed Mar. 22, 2018 and Italian patent Application No. 102019000002615, filed Feb. 22, 2019, the entire contents of both of which are incorporated by reference herein as if fully set forth.

FIELD OF THE INVENTION

The present invention refers to a dovetail tool changer of the type used to constrain tools (EOAT End of Arm Tooling) to robotic arms of industrial manipulators.

BACKGROUND

In the industrial automation sector, the use of robotic manipulators, for example motorized articulated arms which tools can be combined with to operate on the pieces to be manipulated or machined, is well known. Depending on requirements, the tool can be a gripper to grip the objects to be manipulated, pincers, a punch, a suction cup, etc.

In many cases manipulators are designed to mount interchangeable tools. In this case, devices acting as mechanical interface for the functional connection of tools to the respective manipulator are generally used. These tool changers are often identified by the term “quick changer”.

In principle, the tool changers comprise a first portion that can be fixed to the robotic arm and a second portion that can be fixed to the tool. The first portion and the second portion can be reversibly constrained to each other, that is to say that the coupling of these two portions allows the tool to be anchored to the robotic arm and released therefrom.

These devices must not only guarantee the proper tool-manipulator coupling, but also allow a tool change as quick and risk-free as possible for the operators, while ensuring that the tool is not accidentally released when the robotic arm is active.

A particular type of tool changer consists of the so-called dovetail tool changers, which include two plates: a first plate intended to be constrained to a robotic arm—and thus defined robot-side plate—, and a second plate intended to be constrained to a tool—and thus defined tool-side plate. The tool-side plate has a dovetail cross-section. The robot-side plate has a cross-section that is substantially complementary to the cross-section of the tool-side plate; in particular, the robot-side plate defines a pocket into which the tool-side plate can be inserted by sliding on the insertion plane along a longitudinal insertion direction.

In other words, the two plates have conjugate shapes.

For sake of simplicity, hereinafter the robot-side plate will be called the first plate and the tool side plate will be called the second plate.

Due to the shape coupling between the two plates, the second plate cannot disengage the first plate by moving in a direction transversal to the longitudinal insertion direction, but can only engage and disengage the first plate by sliding along the insertion plane.

More specifically, we can identify a state defined as “open”, in which the second plate is not constrained to the first plate, and therefore the tool is not constrained to the robotic arm, a state defined as “intermediate”, in which the second plate is inserted into the first plate but is not locked—and therefore can slip out thereof together with the respective tool—and a state defined as “locked” in which the second plate is inserted into the first plate and is made integral thereto by locking means. The locked state corresponds to the tool having been correctly locked to the robotic arm.

For example, U.S. patent application publication No. 2003/0175075 describes a dovetail tool changer wherein the two plates are locked to each other by providing the first plate and the second plate with tooth sets that face each other when the tool changer is in the intermediate state, i.e. when the second plate is inserted into the first plate. When appropriate thrust means of the first plate are activated, these exert a side thrust on the second plate thus causing the two tooth sets to engage with each other so that the tool changer is brought to the locked state. Although this solution ensures optimal locking, it involves the drawback of requiring great clearance between the two plates when inserting the second plate into the first plate. In addition, the engagement of the two tooth sets causes minimal adjustments of the longitudinal position of the second plate with respect to the first plate.

The catalog 9/2015 from ASS Maschinenbau GmbH (page 12) describes a dovetail tool changer called “SWM” (http://ass-automation.com/katalog/english_new/index.html #p=U1). This device comprises locking clamps positioned on the first plate, at a side, and movable between a backward position, at which they do not exert pressure on the second plate, and a forward position, at which the pressure they exert on the second plate is sufficient to lock the latter in the first plate.

Almost all dovetail tool changers are equipped with locking clamps. Usually, the clamps are operated by adjustable handles that can be used by the operators. The clamps are independent of each other; therefore, the adjustable handles can be used independently of each other as well, and this results in the following major drawback: sometimes the operators do not tighten both locking clamps but just act on one of the two adjustable handles, because of haste or inattention. As a result, the tool changer is brought to the locked state, but the second plate is not safely locked in the first plate. In fact, a single clamp may not exert sufficient pressure on the second plate to keep it locked. The second plate can slip out of the first plate because of the movements of the robotic arm that can move very fast. This circumstance can cause the second plate and the tool anchored thereto to be accidentally disengaged, with obvious safety problems for the operators working around the robotic arm.

SUMMARY

The object of the present invention is therefore to provide a dovetail tool changer, easy to make and use, which in all conditions of use ensures that the second plate is effectively locked in the first plate.

In particular, the object of this invention is to provide a dovetail tool changer in which the locking means of the second plate do not require the use of two different adjustable handles.

Therefore, the present invention relates to a dovetail tool changer according to claim1.

In particular, the tool changer comprises a first plate (robot side) which is intended to be constrained to an external handling system, such as a robotic arm, and a second plate (tool side) which is intended to be constrained to a tool. Preferably the second plate can be inserted along a longitudinal insertion direction into a pocket defined in the first plate. The first and second plates have complementary and conjugate cross sectional shapes, and define a dovetailed coupling.

The tool changer further comprises locking means to lock the second plate in the pocket of the first plate. The locking means comprise in turn at least one, and preferably only one, floating element preferably movable in the direction transversal to the longitudinal insertion direction, between a lock position at which it exerts a thrust onto the second plate and prevents the disengagement thereof with respect to the first plate, and an unlock position, at which the second plate can be separated from the first plate.

Advantageously, the locking means comprise at least one thrust element whose function is to exert a thrust onto the corresponding floating member in order to move the latter to the lock position. The thrust elements are all together (not separately or selectively) susceptible to be displaced along a first direction, and preferably along a first longitudinal direction, in response to a same force exerted by the user; in other words, the thrust elements preferably are displaced along a direction parallel to the insertion direction of the second plate into the first plate. The thrust elements are coupled to the floating element in such a way that the transversal position of the floating element depends univocally on the longitudinal position of the thrust elements.

The important advantage involved in this solution is that the second plate can be locked in the first one by simultaneously acting on all the thrust elements with a single force. Therefore, unlike the known technique, the user does not have to act on several adjustable handles, but with a single force he activates all the thrust elements that in turn push the floating element, or the floating elements if more than one, into the lock position, all at once.

Preferably, the movement of each floating element towards the respective lock position is countered by a spring or equivalent resilient element.

In the preferred embodiment, the tool changer is equipped with a single floating element extending along at least half the length of the first plate, and more preferably along the entire corresponding side of the first plate. In this case, a single floating element is activated by one or more thrust elements, which in turn can all be operated together by the user.

Preferably, the tool changer comprises an activating lever that can be moved by the user precisely in order to exert the force that causes the thrust element, or the thrust elements, to act on the floating element. In particular, the activating lever is movable by the user between a lock position, at which it holds the at least one thrust element in a first longitudinal position corresponding to the lock position of the at least one floating element, and an unlock position, at which it holds the at least one thrust element in a second longitudinal position corresponding to the unlock position of the at least one floating element.

Preferably, the activating lever has a cam profile, for example of irreversible type, active on the thrust element or the thrust elements.

In a first embodiment, the thrust elements are in abutment against the floating element along respective inclined planes. In this embodiment, there is only one floating element that is provided with two inclined planes, and there are two thrust elements each having an inclined plane arranged so that the two thrust elements move longitudinally closer or away to/from each other by the sliding of their own inclined plane along a corresponding inclined plane of the floating element.

Preferably, in this first embodiment, the two thrust elements are susceptible to move closer or away to/from one another depending on the position given by the user to the activating lever. When the activating lever is in the lock position, the thrust elements are in the respective close position and the floating element is in the lock position. When the activating lever is in the unlock position, the thrust elements are in the respective spaced position and the floating element is in the unlock position.

Preferably, in this first embodiment, the two thrust elements are slidingly and longitudinally mounted on at least one rod, and preferably on two rods, parallel to the longitudinal insertion direction. For example, at least one spring or an equivalent resilient element is fitted on the rods and interposed between the two thrust elements; the spring counters, by its compression, the movements of the two thrust elements as they move closer.

In a second embodiment, there is only one thrust element having a single inclined plane. In this embodiment too, the thrust element is in abutment against the floating element.

The thrust element moves longitudinally and slides as its inclined plane is along the inclined plane of the floating element. The thrust element moves longitudinally closer or away to/from the stop side of the first plate.

In this embodiment, the thrust element moves in response to the position given by the user to the actuating lever. When the actuating lever is in the lock position, the thrust element is in close position with respect to the stop side of the first plate and the floating element is in the lock position. When the activating lever is in the unlock position, the thrust elements is in distal position with respect to the stop side and the floating element is in the respective unlock position.

Preferably, at least one spring or equivalent resilient element counters the movement of the thrust element as it moves closer to the stop side.

Preferably, in all embodiments a slider is arranged between the actuating lever and the thrust element. The slider is countered by one or more resilient elements, such as springs or elastomeric elements. Preferably, the slider slides in an opposite groove obtained in the thrust element. The actuating lever is in abutment against the slider, preferably with a conjugate rolling surface.

In a third embodiment the thrust element, preferably only one, is not in abutment against the floating element but is connected thereto by at least one joint, and preferably by two joints, which allow the longitudinal displacements of the thrust element to be converted into transverse movements of the floating element. In practice the floating element, the thrust element and the two joints form all together a four-bar linkage in which the longitudinal movements closer or away to/from a stop side of the first plate are converted into transverse displacements of the floating element moving closer or away to/from the second plate.

In a fourth embodiment, the thrust element is positioned at the stop side of the first plate and is transversely movable with respect to the longitudinal insertion direction of the second plate into the first plate thus getting closer to or away from the left side of the first plate.

The thrust element is connected by means of an articulated lever to the floating element, which is positioned on the right side of the first plate, so that the locking element transversely moves closer or away to/from the second plate as a result of transverse movements of the thrust element.

Preferably, in all embodiments the floating element is equipped with a rigid or flexible tooth having a hooked end able to hook the edge of the second plate when the floating element is in the lock position.

Preferably, all embodiments are provided with a sensor that detects the position of the activating lever and sends a corresponding signal to an external control unit. For example, the sensor is of magnetic type.

All the described embodiments allow the user to lock the second plate in the first one by only one movement of the single activating lever, and—unlike conventional solutions—this allows safety to be improved, thus reducing the risk of accidentally releasing the tools from the manipulators.

In addition, the tool changer according to this invention is even easier to be used with respect to the solutions according to the known art, and requires less time to be activated.

