Gripper head and method for operating the gripper head

Abstract

The present invention relates to a gripper head 1 adapted to grip, hold and release a piece of fabric 2, the gripper head 1 having a first part 11 and a second part 33 with respective conveyor belts 6, 6', an actuator 100 such as a hydraulic actuator, a pneumatic actuator or a motor connected to the second part 33 and configured to rotate the second part 33 relative to the first part 11 to apply a first clamping force to the piece of fabric 2 at a fabric clamping position, and a controller C connected to the actuator 100 and configured to control the actuator 100 so that the second part 33 selectively applies a second, higher clamping force at the clamping position when the conveyor belts 6, 6' are temporarily stopped with the clamping area Z filled with a portion of the piece of fabric 2.

Description

[Technical Field]

[0001] The present invention relates to a gripper including an improved gripper head adapted to grip, hold and release pieces of fabric, particularly for use in commercial laundries where individual pieces of fabric need to be picked and pulled from a pile of several pieces of fabric. [Background technology]

[0002] WO 2019 / 137585 discloses a gripper head including a pair of opposing conveyor belts in Figures 14 and 15. An elongated fabric clamping area is defined between the two conveyor belts facing each other. A spring acts to bias one of the two conveyor belts toward a fabric clamping position, allowing a piece of fabric to be clamped between the two conveyor belts and held in the fabric clamping area.

[0003] A gripper with such a gripper head may preferably comprise a robot arm with a gripper head mounted on its end. Such a gripper is adapted to move the gripper head between a receiving position, where a conveyor belt contacts the piece of fabric to be picked up, and a transfer position, where the picked piece of fabric is transferred, for example, to a conveyor or another gripper. An example of a robot arm with a gripper head is shown in FIG. 1 of WO 2019 / 137585.

[0004] In prior art gripper heads, receiving a piece of fabric is accomplished by actuating the conveyor belt to move in one direction when the gripper head is in the receiving position, so that the portion of the fabric that contacts the conveyor belt is pulled by friction from the pile of fabric into the clamping area. When the clamping area is filled along its length, the conveyor belt is stopped and held stationary, and the gripper head is moved from the pile toward the transfer position, with the portion of the fabric held between the conveyor belt by a clamping force. In the transfer position, the conveyor belt is actuated to move in the opposite direction, thereby releasing the piece of fabric from the clamping area.

[0005] The springs providing the aforementioned clamping forces should be selected to reduce or eliminate the risk of the piece of fabric falling out of the gripper head as it is pulled from the pile and moved towards the transfer position. A sensor mounted on the gripper head can preferably be used to determine when the clamping area is filled so that the clamping force applied by the spring results in a relatively low clamping pressure being applied to the piece of fabric along the length of the clamping area.

[0006] Another example of a gripper head for gripping, holding and releasing pieces of fabric is disclosed in WO 94 / 27900. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 137585 [Patent Document 2] International Publication No. 94 / 27900 Summary of the Invention [Problem to be solved by the invention]

[0008] In commercial laundries, there is a need to be able to use gripper heads of the aforementioned kind to handle bundles of fabric made from delicate materials such as silk, as well as to handle bundles of large and / or heavy pieces of fabric, without leaving pinch marks. Accordingly, it is an object of the present invention to provide an improved gripper head and method of operating a gripper head that eliminates, at least to some extent, the problems associated with handling pieces of fabric of different materials and weights with the same gripper head. [Means for solving the problem]

[0009] According to a first aspect of the invention, a gripper head of the kind mentioned above and defined in the preamble of the claims has the further characterising features of claim 1.

[0010] According to a second aspect of the present invention, as defined in claim 9, a method of operating a gripper head of the kind referred to in claim 1 comprises the step of activating an actuator of the gripper head to selectively apply a first clamping force to a piece of fabric in the clamping area and / or to apply a second, higher clamping force to a piece of fabric in the clamping area.

[0011] Further preferred embodiments of the invention are defined in the dependent claims.

[0012] The present invention may be used in connection with many types of textile pieces, such as one or more of the following: textiles, clothing, towels, sheets, pillowcases, bed sheets, tablecloths, rugs, kitchen towels, mops, dust mats, workwear, gowns, uniforms, shirts, socks, personal clothing, industrial wear, medical wear, food industry wear, infant textiles, bibs, blankets, napkins, cleaning gloves, and other flexible materials in individual items. Any use of the term "textile" below should be construed as referring to one of the above or similar items. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a diagram illustrating the gripper head of the present invention in the environment in which it is intended to operate. [Figure 2a] 1A and 1B are front and back views of an embodiment of a gripper head of the present invention, with and without a housing, without showing an actuator disposed in the gripper head. [Figure 2b] 2b is an exploded view of a gripper head of the present invention similar to the gripper head shown in FIG. 2a, including a spring, without showing the actuator disposed in the gripper head. [Figure 3a] 2b shows a gripper head of the invention similar to that of FIG. 2a, in a front view, placed in one of two positions by an actuator; FIG. [Figure 3b] 2b shows a gripper head of the present invention, similar to that of FIG. 2a, placed in another of two positions by an actuator, as seen in a front perspective view. DETAILED DESCRIPTION OF THE INVENTION

[0014] The invention will now be described in more detail by reference to two examples.

[0015] FIG. 1 shows a gripper with a robot arm 26 supporting a gripper head 1, with the gripper head 1 holding a portion of a piece of fabric 2, in the process of transporting the piece of fabric 2 from a pile 4 of similar pieces of fabric to a conveyor or to another gripper 5.

[0016] When large pieces of fabric 2, such as linen, are being processed, it may be desirable to have the robot arm 26 lift the gripper head 1 to an elevated position such that a portion P of the piece of fabric 2, located either approximately halfway or + / −10% of halfway between the portion held by the gripper head 1 and the end E of the hanging piece of fabric 2, can be grasped by the gripper head of the gripper 5. This may be done by first determining the dimension of the piece of fabric 2 held by the gripper head 1, or to be held by the gripper head 1, and then moving the robot arm 26 with the piece of fabric 2 to an elevated position above the gripper 5 where the piece of fabric 2 is carried, the elevated position being higher above the pile 4 for larger pieces of fabric 2 than for smaller pieces of fabric 2. A controller (not shown) may determine the dimension, for example using a camera, or the determination may be made visually or otherwise by an operator, either for each piece of fabric 2 in the pile or for each piece of fabric 2 in the pile 4. In this way, the large-sized piece of fabric is subsequently conveyed by the gripper 5 in a folded form, thereby reducing the length of the end of the piece of fabric 2 at which the piece of fabric 2 is held by the gripper 5 .

[0017] FIG. 2a shows a gripper head 1 of the present invention having a first portion 11 that can be mounted to the end of a robot arm, such as robot arm 26 as shown in FIG. 1, for moving the gripper head 1 around in three-dimensional space.

[0018] Figure 2a corresponds to Figure 14 of WO 19137585, but the gripper head 1 shown further includes an actuator (not visible in Figure 2a) disposed within the first portion 11 and for purposes discussed below.

[0019] Generally, the first portion 11 supports two opposing conveyor belts 6, 6' defining a nip area Z (see FIG. 3a) between them, i.e., where they face each other, such that fabric pieces 2 contacting the conveyor belts 6, 6' within the nip area Z can be drawn in by friction as the conveyor belts 6, 6', submerged in the pile 4 of fabric pieces 2, move in a first direction. As shown, the first 6 of the two conveyor belts 6, 6' is a loop that follows around a first set of rollers 8, 18, and the second 6' of the conveyor belts is a loop that follows around a second set of rollers 8', 18'. A drive, preferably in the form of a motor 17, is configured to first move the opposing surfaces of the two conveyor belts 6, 6' in an upward direction, then stop the movement of the conveyor belts 6, 6' and hold them when the clamping area Z is filled with a portion of the piece of fabric 2, and then move the opposing surfaces of the two conveyor belts 6, 6' in an opposite downward direction to release the piece of fabric 2 from the clamping area Z.

[0020] Generally, the second part 33 of the gripper head 1 supports the second roller 18' of the second set of rollers 8', 18' and is pivotally mounted to the first part 11 so that it can be rotated relative to the first part 11 about the axis of rotation 35 of the first (upper) roller 8' of the second set of rollers 8', 18' to and from the fabric clamping position shown in Figure 2b and similarly in Figure 3a, in which the second roller 18' of the second set of rollers 8', 18' and the second roller 18 of the first set of rollers 8, 18 are adjacent to each other with the conveyor belts 6, 6' and define a clamping zone Z therebetween. When the gripper head 1 is rotated away from the fabric clamping position, i.e., to what may be called the open configuration of the gripper head 1 as shown in Figures 2a and 3b, gripping of the fabric piece 2 in the pile 4 and pulling it into what becomes the clamping area Z after the second part 33 has been rotated to its fabric clamping position is more reliably achieved, and may be necessary if the fabric piece 2 is relatively hard.

[0021] In a slight modification of the gripper head 1 shown in Figure 2a, a spring 34 is arranged to bias the second part 33 towards the fabric clamping position (see Figure 2b). This embodiment has the advantage that the second part 33 can, wherever necessary, slightly deviate from the clamping position when the piece of fabric 2 is picked up.

[0022] An actuator 100, such as, but not limited to, a hydraulic actuator, pneumatic actuator, or motor, connected to the first portion 11 is also connected to the second portion 33 at an extension of the second portion 33 above the level of the upper roller 8′. The actuator 100 is configured to rotate the second portion 33 relative to the first portion 11 about an axis 35 of rotation of the upper roller 8′ and to hold the second portion 33 in a selected position, such as in the fabric clamping position shown in FIGS. 2b and 3a, where a portion of the fabric piece can be held clamped between the two conveyor belts 6, 6′ in the clamping zone Z. FIGS. 2a and 3b show the second portion 33 displaced from the clamping position by the actuator 100. A controller C acts to control the actuator 100.

[0023] In a first mode of operation, the gripper head 1 is configured such that the second portion 33 in the aforementioned clamping position shown in FIG. 3 a applies a first, relatively low clamping force to the piece of fabric 2 held by the gripper head 1. This low force may preferably be applied while the piece of fabric 2 is a) pulled into the clamping zone Z by the moving conveyor belts 6, 6′, b) held in the clamping zone Z, and c) moved to the transfer position by the robot arm 26. This may be the case if the piece of fabric 2 is believed to be made of a delicate material and requires holding using a low clamping pressure. The first, low clamping force may be applied by the actuator 100, by the aforementioned spring 34, or by the actuator 100 and spring 34 acting together.

[0024] In another mode of operation, the actuator 100 can be operated so that the second part 33 applies a selected second and higher clamping force when this other mode is selected, for example, from i) when the fabric piece 2 is completely drawn into the clamping zone Z until the fabric piece 2 is released from the gripper head 2 at its transport position, or ii) from the start of the process of drawing the fabric piece 2 into the clamping zone Z until the fabric piece 2 is finally released from the gripper head 2 at its transport position (in the latter case, the controller C of the gripper head 1 applies the second, higher clamping force in due time). The second, higher clamping force can preferably be applied by the actuator 100. This mode of operation can preferably be selected when a heavy fabric piece of a non-delicate nature is being drawn from the pile 4.

[0025] In an alternative embodiment, where the aforementioned spring 34 provides a higher clamping force, the actuator 100 is configured to reduce that clamping force when the gripper 1 operates in the aforementioned first mode.

[0026] The controller C may be connected to a sensor for recognizing the type of fabric in the pile 4 and therefore for determining whether the gripper head 1 should be operated in a first mode or a second mode. Alternatively, an operator may manually select when the gripper head 1 should operate in one or the other mode.

[0027] If desired, the controller C may be configured to control the actuator 100 to deflect the second portion 33 from the clamping position, as shown in Figures 2a and 3b, which may be desirable early in the phase when the fabric is being drawn between the two conveyor belts 6, 6'.

[0028] It is noted that the respective clamping forces can be changed as desired using a controller to appropriately set the actuators and / or by replacing any springs as described above.

Claims

1. A gripper head (1) adapted to grip, hold and release a piece of fabric (2), a first part (11) supporting two conveyor belts (6, 6') configured to define a nipping zone (Z) therebetween, such that when said conveyor belts (6, 6') move in a first direction, a portion of a piece of fabric (2) in contact with said conveyor belts (6, 6') can be drawn into said nipping zone, a first of said conveyor belts (6) following around a first set of rotatable rollers (8, 18) and a second of said conveyor belts (6') following around a second set of rotatable rollers (8', 18'); at least one drive (17) configured i) to move the conveyor belt (6, 6') in the first direction, ii) to temporarily stop the movement of the conveyor belt (6, 6') when the clamping area (Z) is filled with the portion of the piece of fabric (2), and iii) to move the conveyor belt (6, 6') in an opposite second direction; a second part (33) supporting a second roller (18') of the second set of rollers (8', 18'), the second part (33) pivotally mounted on the first part (11) to rotate relative to the first part (11) about a rotation axis (37) of a first roller (8') of the second set of rollers (8', 18') to and from a cloth clamping position, the clamping area (Z) being defined between the two conveyor belts (6, 6') when in the clamping position, and the gripper head (1) being configured to apply a first clamping force to the piece of cloth (2) within the clamping area (Z) when in the clamping position; and an actuator (100), such as a hydraulic actuator, a pneumatic actuator or a motor, connected to the second part (33), the actuator (100) being configured to rotate the second part (33) relative to the first part (11); a controller (C) connected to the actuator (100), configured to control the actuator (100) for the second portion (33) to apply a second, higher clamping force to the piece of fabric (2) in the clamping zone (Z) at the clamping position; A gripper head (1) characterized by:

2. 2. The gripper head (1) of claim 1, wherein a spring (34) biases the second portion (33) towards the fabric clamping position.

3. The gripper head (1) of claim 2, wherein the spring (34) provides the first clamping force.

4. The gripper head (1) of claim 2, wherein the controller (C) is configured to control the actuator (100) to apply the first clamping force together with the spring (34).

5. 2. The gripper head (1) of claim 1, wherein the controller (C) is configured to control the actuator (100) to apply the first clamping force to the piece of fabric (2) while it is being pulled into the clamping zone (Z).

6. 6. The gripper head (1) of claim 1, wherein the controller (C) is configured to control the actuator (100) to rotate the second part (33) from the clamping position to a position where the conveyor belts (6, 6') are spaced apart to grip a piece of cloth (2) in a pile (4), and to retract the second part (33) into what will become the clamping zone (Z) after being rotated to its cloth clamping position.

7. 7. The gripper head (1) according to any one of claims 1 to 6, wherein a first roller (8) of the first set of rollers (8, 18) and a first roller (8') of the second set of rollers (8', 18') are interconnected by gears (16, 16') for rotating the first rollers (8, 8') about their respective axes of rotation (37), and at least one of the gears (16) is driven by a motor (17) for clockwise and counterclockwise rotation.

8. A gripper comprising a gripper head (1) according to any one of claims 1 to 7, mounted on the end of a robot arm (26) for moving the gripper head (1) about in three-dimensional space.

9. A method of operating a gripper head (1) adapted to grip, hold and release a piece of fabric (2), said gripper head (1) comprising: a first part (11) supporting two conveyor belts (6, 6') configured to define a nipping zone (Z) therebetween, such that when said conveyor belts (6, 6') move in a first direction, a portion of a piece of fabric (2) in contact with said conveyor belts (6, 6') can be drawn into said nipping zone, a first of said conveyor belts (6) following around a first set of rotatable rollers (8, 18) and a second of said conveyor belts (6') following around a second set of rotatable rollers (8', 18'); at least one drive (17) configured i) to move the conveyor belt (6, 6') in the first direction, ii) to temporarily stop the movement of the conveyor belt (6, 6') when the clamping area (Z) is filled with the portion of the piece of fabric (2), and iii) to move the conveyor belt (6, 6') in an opposite second direction; a second part (33) supporting a second roller (18') of the second set of rollers (8', 18'), the second part (33) pivotally mounted on the first part (11) to rotate relative to the first part (11) about a rotation axis (37) of a first roller (8') of the second set of rollers (8', 18') to and from a cloth clamping position, the conveyor belt (6, 6') defining the clamping area (Z) therebetween at the clamping position, and the second part (33) configured to apply a first clamping force to the piece of cloth (2) at the clamping position in a process of being drawn into the clamping area (Z) by the conveyor belt (6, 6') moving in the first direction; an actuator (100), such as a hydraulic actuator, a pneumatic actuator or a motor, connected to the second part (33), the actuator (100) being configured to rotate the second part (33) and hold it in the cloth clamping position; and activating the actuator (100) to apply a first clamping force to the piece of fabric (2) in the clamping area (Z) and / or to apply a second, higher clamping force to the piece of fabric (2) in the clamping area (Z).

10. 10. The method of claim 9, further comprising rotating the second part (33) into the clamping position by the actuator (100) before or after the piece of fabric (2) is pulled into the clamping area (Z).

11. 11. The method according to claim 9 or 10, wherein the second part (33) is rotated away from the cloth clamping position to a position where the conveyor belts (6, 6') are spaced apart in order to grip a piece of cloth (2) in the pile of cloth (4), thereby drawing the piece of cloth (2) into what will become the clamping area (Z) after the second part (33) is rotated to the cloth clamping position.

12. The gripper head (1) is mounted on the end of a robot arm (26) for moving the gripper head (1) about in three-dimensional space, and the method comprises: i) determining the dimensions of a piece of fabric (2) held by said gripper head (1) or to be held by said gripper head (1); ii) then moving the robot arm (26) with the piece of fabric (2) to a raised position above the gripper (5) where the piece of fabric (2) is carried, the raised position being higher for larger pieces of fabric (2) than for smaller pieces of fabric (2); 12. The method of any one of claims 9 to 11, comprising:

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