Placement head for pick-and-place equipment

Abstract

A placement head for a pick-and-place apparatus includes a housing, a rigid handling device, a first resilient element, a blocking means, and a detection device. The housing includes a passageway defining an axis. The rigid handling device includes a shaft portion partially received within the passageway. The first resilient element is configured to generate a first force between the housing and the rigid handling device in a first direction generally parallel to the axis, urging the first end of the shaft portion away from the first end of the passageway. The blocking means is configured to releasably block the first end of the shaft portion from moving in a second direction opposite the first direction toward the first end of the passageway. The detection device is configured to detect a magnitude of movement of the rigid handling device relative to the housing generally parallel to the axis.

Description

[Technical Field]

[0001] The present invention relates to a placement head for a pick-and-place machine, a manipulator for a pick-and-place machine, a pick-and-place machine, and a method for placing components using these. [Background technology]

[0002] Pick-and-place devices are known in the art. They are used, for example, to mount electronic components on printed circuit boards (PCBs). These devices select components from a first location and place them at a second location using a placement head. To avoid damaging these components during the manufacturing process, the force used to pick and / or place such components can be limited to a predetermined threshold. This can be achieved by providing a resilient element between the placement head, configured to hold and release the component, and the pick-and-place device, configured to move the placement head between the pick and place locations, and by providing a controller configured to control the movement of the placement head by the pick-and-place device and the force applied to the component by the placement head. Such a controller is typically configured to slow the movement of the placement head as it approaches the pick or place location before making physical contact to prevent or limit large force perturbations due to inertia. Typically, such a controller is further connected to a contact detection device configured to detect physical contact between the placement head and the pick or place location and to control the force applied to the component by the placement head. Following detection of physical contact, the controller controls the distance the placement head is displaced relative to the pick or place location to prevent the force from exceeding a predetermined value.

[0003] A control system can control the force by controlling the drive current of the actuator of the pick-and-place device, for example by relating this to a motor force constant. This solution is suitable for certain thresholds above a few newtons. However, over time, the size of parts is continuously decreasing, and with it, the forces exerted on these parts are also decreasing. Therefore, the ability to control smaller forces is required. Therefore, controlling the force by controlling the drive current of the actuator is not suitable in all these cases.

[0004] Small forces can be more precisely controlled by pick-and-place equipment that includes load cells. However, the inherent stiffness of such load cells requires that the speed or acceleration at which the placement head moves must be further reduced, negatively impacting productivity and manufacturing costs. For example, a load cell with high stiffness will have a very short stopping distance and therefore a slower speed, whereas a load cell with low stiffness will have a lower acceleration due to the resulting lower natural frequency.

[0005] Another known solution for controlling small forces is to provide a placement head with a pressure chamber with an adjustable pressure that can be adjusted to correspond to a threshold value. However, using such a placement head in a high-productivity environment can cause erratic movement of the placement head's components, potentially resulting in excessive wear on the placement head and damage to the picked components. Furthermore, in such situations, the force cannot be precisely controlled and cannot be quickly adapted due to the settling time of the pressure and gas supply in the pressure chamber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 077550 [Patent Document 2] U.S. Patent No. 5,420,488 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-018905 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-210995 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is an object of the present invention to overcome at least one and preferably all of the disadvantages associated with the prior art. [Means for solving the problem]

[0008] According to a first aspect of the present invention, the object of the present invention is achieved by a placement head as set out in the appended claims.

[0009] A placement head according to the present invention comprises a housing. The housing may include a passageway defining an axis along the passageway. The placement head may further comprise a rigid handling device comprising a shaft portion. The shaft portion may be partially received within (along its length) the passageway. The housing and the shaft portion may collectively define a linear bearing. The shaft portion may be configured to move along the passageway generally parallel to the axis. The housing may form a guiding portion of the linear bearing, and the shaft portion may form a translating portion of the linear bearing, for example, configured to slide or glide along the passageway. A first end of the shaft portion may extend from a first end of the passageway. The first end of the shaft portion may be configured to receive (e.g., releasably connect to) a nozzle suitable for holding a component (e.g., a PCB component). The placement head may comprise a first resilient element configured to generate a first force between the housing and the rigid handling device, the first force urging the first end of the shaft portion away from the first end of the passage in a first direction generally parallel to the axis. The placement head may comprise a blocking means (e.g., a blocking unit or mechanism) configured to releasably block the first end of the shaft portion from moving (substantially) toward the first end of the passage in a second direction opposite the first direction. The placement head may further comprise a detection device suitable for detecting a magnitude of movement of the rigid handling device relative to the housing generally parallel to the axis.

[0010] Such a placement head achieves the objectives of the present invention because, during phases associated with high accelerations, such as a translocation phase in which a component is moved (e.g., roughly) between a pick position and a place position, the blocking means can block movement of the shaft relative to the housing to prevent damage or loss of the picked component, while during phases associated with low accelerations, such as a pick-and-place phase in which a component is placed or picked, the blocking means is released and the first elastic element can generate a first force that depends on the magnitude of movement between the rigid handling device and the housing. By detecting the magnitude of this movement using a detection device, the force applied to the component by the nozzle can be accurately determined and controlled. Thus, the combination of these means enables precise control of the placement force applied by the nozzle in a high-speed assembly environment. Furthermore, the force applied by the nozzle can be stored for future reference, for example, to identify manufacturing parameters that may be related to problems that arise at a later time.

[0011] A further advantage of such a placement head is that the placement force can be accurately measured and stored for future reference, for example to identify manufacturing parameters that may be related to problems that arise at a later time.

[0012] The first elastic element may include a first end and a second end opposite the first end of the first elastic element. The first elastic element may be (rotatably) connected to the housing via the first end of the first elastic element so that the first end of the first elastic element and the housing move together; for example, the first end of the first elastic element may be fixedly connected to the housing so that the first end of the first elastic element has a fixed relative position with respect to the housing. The first end of the first elastic element may be connected to the housing via a stage. The first elastic element may be connected to a shaft portion (e.g., an end plate) via the second end of the first elastic element so that the second end of the first elastic element and the shaft portion move together; for example, the second end of the first elastic element may be fixedly connected to the shaft portion so that the second end of the first elastic element and the shaft portion move together. An embodiment comprising such a first resilient element has the advantage that the first resilient element can be provided away from the first end of the shaft portion.

[0013] The first elastic element is configured such that the first force is correlated to the magnitude of movement, allowing for a simple and fast method for measuring and controlling the deployment force. Preferably, the first elastic element is configured such that the first force has a linear relationship with or is proportional to the magnitude of movement, allowing for a simple method for controlling the deployment force with substantially uniform resolution over a range of thresholds.

[0014] The first resilient element may comprise a mechanical device (e.g., a spring), a first pressure chamber, e.g., a hydraulic / pneumatic device such as an (airtight) bellows or a piston and cylinder, and / or a magnetic device (e.g., a magnet or a voice coil). The first resilient element may be configured to be compressed or expanded when the rigid handling element is displaced relative to the housing in a direction generally parallel to the axis, e.g., a first direction.

[0015] The preventing means may include a fastening means (e.g., a fastener) configured to physically interact with both the housing and the rigid handling element, such as a pin configured to engage both the housing and the rigid handling element, or a friction fit including a piezoelectric element (e.g., a piezoelectric motor) to provide friction between the housing and the rigid handling element.

[0016] The blocking means may be configured to provide an adaptable offset force, or may be configured to apply an offset force that urges the first end of the shaft portion in a first direction away from the first end of the passageway, and may be configured to substantially prevent movement of the rigid handling element relative to the housing, for example, up to a predetermined load. The blocking means may include a first resilient element, and the blocking means is configured to apply an offset force that urges the first end of the shaft portion in a first direction away from the first end of the passageway. Applying such an offset force may be achieved, for example, by applying a preload to the first resilient element. For example, the first resilient element may be compressed in some embodiments, and the blocking means may include a first pressure chamber (e.g., a bellows or a piston and cylinder) or a spring as the first resilient element. In another example, the pressure in the first resilient element may be increased in some embodiments, and the blocking means may include a first pressure chamber (e.g., a bellows or a piston and cylinder) as the first resilient element.

[0017] The blocking means may be configured to provide an adaptable resistance to deformation, or to adapt the resistance to deformation (e.g., stiffness) of the placement head, such as adaptable resistance to movement of the rigid handling device relative to the housing. The blocking means may include a first elastic element, the blocking means being configured to adapt the stiffness of the first elastic element. For example, the first elastic element may be compressed in embodiments, and the blocking means may comprise a first pressure chamber (e.g., a bellows or a piston and cylinder) or a spring as the first elastic element. In another example, the pressure in the first elastic element may be increased in embodiments, and the blocking means may comprise a spring as the first elastic element. Advantageously, actuating the blocking means to block the first end of the shaft portion from moving in a second direction opposite to the first direction toward the first end of the passageway forces the rigid handling device or shaft portion into a blocking position, and the first end of the shaft portion is maximally extended from the first end of the passageway.

[0018] The blocking means may be configured to adapt at least one of an offset force urging the first end of the shaft portion in a first direction away from the first end of the passage and a stiffness of the first elastic element. Preferably, the blocking means is configured to adapt both an offset force urging the first end of the shaft portion in a first direction away from the first end of the passage and a stiffness of the first elastic element.

[0019] The first elastic element may include a pressure chamber configured to provide an adaptable stiffness suitable for preventing movement of the rigid handling element relative to the housing. For example, the first elastic element may include a conduit fluidly connected to the pressure chamber, which may be used to control the pressure in the pressure chamber by supplying gas (e.g., air) to the pressure chamber or exhausting gas from the pressure chamber. A preventing means comprising such a first elastic element may be configured to control the pressure in the first pressure chamber such that the stiffness of the first elastic element may be dynamically adapted, for example, during an operation to handle a (single) part.

[0020] In an advantageous embodiment, the first elastic element comprises a bellows. Bellows offer the advantages of being lightweight, simple to construct, and substantially frictionless during operation. Furthermore, by controlling the pressure within the bellows, the mechanical properties of the bellows (e.g., offset force, stroke) can be controlled relatively easily and quickly. This allows, for example, to control the offset force without affecting the stroke of a rigid handling device relative to the housing. In one advantageous embodiment, increasing the pressure within the bellows allows for the use of a bellows with a lower stiffness while maintaining the offset force, thereby improving the resolution of the measured force. In another advantageous embodiment, the bellows can be housed and the pressure controlled to expand the bellows allows for the use of a bellows with a nominal length shorter (i.e., stress-free) than the clearance, for example, to increase the stroke, increase the resolution of the measured force, or reduce the impact mass. Bellows can also be used to compensate for manufacturing tolerances of the bellows that may affect the mechanical properties. The bellows can include multiple bellows arranged in parallel (e.g., coaxially) and / or in series to improve control of the mechanical properties. For example, one of the bellows may be maintained at a constant pressure as an offset, while another of the bellows is used to control the spring constant.

[0021] In particularly advantageous embodiments, the bellows is made substantially of one or more polymers. Using polymers to manufacture the bellows can reduce manufacturing costs compared to, for example, using metal. This also simplifies the manufacture of smaller bellows, which may require lower stiffness. In embodiments in which the bellows is made substantially of one or more polymers, a temperature sensor is preferably provided to measure the temperature of the bellows, which may be used to compensate for the effect of temperature on the mechanical properties of the bellows, such as stiffness (e.g., spring constant).

[0022] Alternatively or additionally, the first resilient element may comprise a spring configured to provide at least one of an adaptable offset force and an adaptable stiffness.

[0023] Alternatively or additionally, the first elastic element may comprise a magnetic device configured to provide at least one of an adaptive offset force and an adaptive stiffness. For example, a magnetic device configured to controllably generate a magnetic field may be provided. Such a magnetic field may generate a magnetic force acting between the housing and the rigid handling element to resist deformation of the placement head. This magnetic field may be generated, for example, using a voice coil provided on one of the housing and the rigid handling device. Such a magnetic field may interact with a magnetic field generated by another voice coil or with a magnetic material provided on the other of the housing and the rigid handling device.

[0024] Preferably, the linear bearing is configured as a gas bearing. In such an embodiment, the linear bearing may be configured to supply gas to the control device to control the stiffness of the first pressure chamber. Such an embodiment has the advantage that the preventing means does not require an (additional) external gas source to supply gas to control the stiffness of the first pressure chamber.

[0025] The preventing means may include a gas inlet configured to supply gas to the first pressure chamber. The gas inlet may be further configured to control the pressure in the first pressure chamber. For example, the gas inlet may comprise a (controllable) pressure valve, through which gas is supplied to the first pressure chamber.

[0026] The preventing means may include a gas outlet configured to exhaust gas from the first pressure chamber. The gas outlet may be configured to control the pressure in the first pressure chamber. For example, the gas outlet may comprise a (controllable) pressure relief valve that controls the pressure in the first pressure chamber, such as an upper threshold pressure in the first pressure chamber.

[0027] The placement head may include a second resilient element that generates a second force that urges the first end of the shaft portion in a first direction away from the first end of the passageway. An advantage of providing such a second resilient element is that the blocking means may be used to control the first force and provide an offset to the second force.

[0028] Alternatively, the placement head may include a second resilient element that generates a second force that urges the first end of the shaft portion in a second direction toward the first end of the passageway. An advantage of providing such a second resilient element is that it can be used to compensate for at least part of the weight of a rigid handling device.

[0029] Preferably, the second elastic element may be configured to passively generate the second force, for example, based on movement. For example, the second elastic element may include a second spring and / or a second pressure chamber, such as an airtight bellows or a piston and cylinder. The second pressure chamber may be configured to compress or expand when the rigid handling element is displaced relative to the housing generally parallel to the axis. The placement head or second elastic element may be configured such that the second force is correlated to the magnitude of movement, enabling a simple and fast method for controlling the placement force. Preferably, the placement head or second elastic element may be configured such that the second force has a linear relationship with or is proportional to the magnitude of movement, enabling a simple method for controlling the placement force with substantially uniform resolution over a range of thresholds. The placement head or second elastic element may be configured to provide an adaptive stiffness and / or offset force between a first state and a second state, having the first state when handling a first component and the second state when handling a second component.

[0030] The second elastic element may be arranged to generate a second force between the housing and the rigid handling device. The second elastic element may include a first end and a second end disposed opposite the first end. The second elastic element may be connected to the housing via the first end of the second elastic element such that the first end of the second elastic element and the housing move together, e.g., the first end of the second elastic element is fixedly connected to the housing. The second elastic element may be connected to the rigid handling device via the second end of the second elastic element such that the second end of the second elastic element and the rigid handling device move together, e.g., the second end of the second elastic element is fixedly connected to the rigid handling device.

[0031] In an advantageous embodiment, the second elastic element comprises a bellows, which offers the advantages of being lightweight, simple to construct and virtually frictionless during operation.

[0032] The cross section of the passage perpendicular to the axis can have any shape, but preferably the cross section is circular, and more preferably the passage is cylindrical. An advantage of a cylindrical passage is that it is easy to manufacture, for example by drilling a hole in the housing. Preferably, the housing has a through hole forming the passage, and such a passage can have a second end located opposite the first end of the passage. Advantageously, the shaft portion has a shape corresponding to the shape of the passage, allowing for the formation of a linear bearing. The passage can completely surround the shaft portion. Preferably, the passage and the shaft portion are configured so that the linear bearing forms a gas bearing to reduce friction and reduce wear.

[0033] The shaft portion may have a second end disposed opposite the first end of the shaft portion. Preferably, the second end of the shaft portion extends from the second end of the passageway. The rigid handling device may further include an end plate attached to the shaft portion and extending from the second end of the shaft portion. The end plate may be configured to interact with the second end of the second elastic element; for example, the end plate may be configured to abut or be fixedly connected to the second end of the second elastic element. Such an embodiment has the advantage that the second elastic element can be moved away from the first end of the shaft portion. The end plate may be configured to form an end stop for the shaft portion moving along the passageway, for example, moving along the passageway in a first direction.

[0034] The passageway may include a first portion and a second portion. The first portion of the passageway may be disposed between a first end of the passageway and a second portion of the passageway. The second portion of the passageway may be disposed between the second end of the passageway and the first portion of the passageway. The first portion of the passageway may be configured to have a first diameter. The second portion of the passageway may be configured to have a second diameter. Preferably, the first diameter is greater than the second diameter.

[0035] The shaft portion may include a first portion and a second portion. The first portion of the shaft portion may be disposed between the first end of the shaft portion and the second portion of the shaft portion. The second portion of the shaft portion may be disposed between the second end of the shaft portion and the first portion of the shaft portion. The first portion of the shaft portion may be configured to have a third diameter. The second portion of the shaft portion may be configured to have a fourth diameter. Preferably, the first and third diameters are configured to form a first matching pair of diameters suitable for forming at least a portion of a linear bearing. Additionally or alternatively, the second and fourth diameters are configured to form a second matching pair of diameters suitable for forming at least another portion of a linear bearing. The passageway and the shaft portion may be configured to form a pocket (e.g., an air pocket) between a first interface of the first and second portions of the passageway and a second interface of the first and second portions of the shaft portion, the pocket being compressible / expandable. Preferably, the pocket defines a first pressure chamber to reduce the weight and size of the placement head.

[0036] The passageway may include a second end opposite the first end of the passageway. The shaft portion may include a second end opposite the first end of the shaft portion. The passageway may include a first portion extending toward the first end of the passageway having a first diameter and a second portion extending toward the second end of the passageway having a second diameter. The shaft portion may include a first portion extending toward the first end of the shaft portion and having a third diameter related to the first diameter, and a second portion extending toward the second end of the shaft portion and having a fourth diameter related to the second diameter. The passageway and the shaft portion may be configured to form a first pressure chamber between a first interface between the first and second portions of the passageway and a second interface between the first and second portions of the shaft portion. The first diameter is preferably greater than the second diameter.

[0037] The first end of the shaft portion may form a nozzle suitable for holding a component (e.g., a PCB component), may comprise a nozzle, or may be configured to receive (e.g., removably connect to) a nozzle for holding a component. The latter allows for replacement of the nozzle in case of wear or when different components require different nozzles. Preferably, the first end of the shaft portion is configured to (releasably) rigidly connect to the nozzle to improve precise control of the placement force.

[0038] The detection device may include any type of sensor (e.g., magnetic, capacitive, or optical) suitable for detecting the magnitude of movement. Such a sensor may be fixedly connected to any part of the housing and / or rigid handling device. Preferably, the detection device is configured to directly detect the magnitude of movement of the end plate relative to the housing. For example, the sensor may be fixedly connected to a side of the housing opposite the end plate, and / or the sensor may be fixedly connected to a side of the end plate opposite the side of the housing, etc. Such an embodiment has the advantage that the detection device may be moved away from the first end of the shaft portion.

[0039] According to a second aspect of the present invention, the above object is achieved by a manipulator for a pick-and-place apparatus, comprising a placement head according to the first aspect and a base, the manipulator being configured to move the placement head relative to the base. For example, the manipulator may comprise an actuation means (e.g., an actuation mechanism) connected at a first end to the base and at a second end to the placement head, the second end of the actuation means comprising a stage (e.g., a motion platform) connected to the placement head. The actuation means may be configured to move the placement head relative to the base. The actuation means may, for example, comprise an actuator including at least one (linear) actuator, preferably multiple (linear) actuators. The actuation means may, for example, be configured to move the placement head relative to the base generally parallel to an axis (e.g., in a first direction). To this end, the actuation means may comprise a first actuator, such as a linear actuator oriented parallel to the axis. Preferably, the actuation means is further configured to move the placement head relative to the base in a plane perpendicular to the axis, such that the placement head can be moved within a predetermined volume. The actuation means may therefore comprise a plurality of actuators configured to move the placement head. The actuation means may, for example, comprise second and third linear actuators which, together with the first linear actuator, form three orthogonal linear actuators configured to move the placement head along three orthogonal axes. Preferably, the second end of the actuation means is connected to the housing of the placement head such that the second end and the housing move together.

[0040] The second end of the actuation means may include a rotary actuator for aligning the picked component with the place location. Such a rotary actuator may be connected to the first elastic element such that the first end of the shaft portion is rotatable about an axis relative to the housing. For example, a fixed portion of the rotary actuator may be fixedly connected to the second end of the actuation means, and a rotating portion of the rotary actuator may be fixedly connected to the first elastic element (e.g., the first end of the first elastic element).

[0041] The manipulator may further include a control unit connected to the blocking means. The control unit may be configured to control the blocking means between a blocked state and a released state. For example, the blocking means in the blocked state generates a first force that blocks the rigid handling device or shaft portion from moving along the passage. In the released state, the blocking means is configured to allow movement of the rigid handling device or shaft portion relative to the housing. For example, the blocking means in the released state generates a first force that allows the shaft portion to move along the passage. Preferably, the first force in the blocked state is greater than the first force in the released state. In the blocked state, the blocking means may be configured to hold the rigid handling device or shaft portion in a blocked position. Advantageously, the first end of the shaft portion is maximally extended from the first end of the passage in the blocked position. An advantage of such a manipulator is that it allows large accelerations of the placement head in the locked state and allows small forces to be accurately measured in the released state.

[0042] The control unit may be further configured to control the movement of the stage to move the placement head during the transfer phase and the pick-and-place phase. During the transfer phase, the placement head can be moved between a pick position and a place position. During the pick-and-place phase, the placement head can perform one of picking and placing a component at the pick position and the place position, respectively. The control unit may be further configured to maintain a blocked state during the transfer phase and a released state during the pick-and-place phase. This allows large movements during the transfer phase to be performed with high acceleration, while allowing small forces during the pick-and-place phase to be accurately measured. An advantage of such a manipulator is that it can increase productivity without risking damage to the component or placement head or increasing component loss due to irregular movement of the rigid handling device relative to the housing.

[0043] The control unit may further be connected to a detection device (e.g., a measurement device). Such a control unit may be configured to stop the movement of the stage in the first direction when the magnitude of the movement reaches a predetermined threshold to avoid damage to the component. Preferably, the control unit is configured to stop the movement of the stage in the first direction during the pick-and-place phase.

[0044] According to a third aspect of the present invention, the above object is achieved by a pick-and-place apparatus comprising a placement head according to the first aspect or a manipulator according to the second aspect.

[0045] According to a fourth aspect of the present invention, the objective is achieved by a method of placing a component using a placement head according to the first aspect, a manipulator according to the second aspect, or a pick-and-place apparatus according to the third aspect, the method comprising the steps of: activating a blocking means to block the shaft portion from moving relative to the housing when the placement head moves between a pick position and a place position; and activating the blocking means to release the shaft portion to allow it to move along the path during a pick-and-place phase in which the placement head picks and places a component at the pick position and the place position, respectively. Preferably, the shaft portion is maintained in the blocked position during the transfer phase. [Brief explanation of the drawings]

[0046] [Figure 1A] 1 shows a cross-sectional view of a first embodiment of a placement head according to the present invention with a rigid handling device in a blocked state; [Figure 1B] 1 shows a cross-sectional view of a first embodiment of a placement head according to the present invention, with a rigid handling device in a released state; [Figure 2A] 10 depicts a cross-sectional view of a second embodiment of a placement head according to the present invention in a released state. [Figure 2B] 10 depicts a cross-sectional view of a second embodiment of a placement head according to the present invention in a released state. [Figure 3A] 1A-1D represent cross-sectional views of a first embodiment of a manipulator according to the invention at various stages of placing a part; [Figure 3B] 1A-1D represent cross-sectional views of a first embodiment of a manipulator according to the invention at various stages of placing a part; [Figure 3C] 1A-1D represent cross-sectional views of a first embodiment of a manipulator according to the invention at various stages of placing a part; DETAILED DESCRIPTION OF THE INVENTION

[0047] Aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numerals indicate like features.

[0048] Referring to FIGS. 1A, 1B, 2A, and 2B, the placement head 100, 200 includes a housing 101, 201. The housing typically forms one of the connection elements between the placement head and a stage of a pick-and-place device. The housing 100, 200 includes a through-hole forming a passage 102, 202. The passage 102, 202 extends between a first opening in the housing that forms a first end 107, 207 of the passage 102, 202 and a second opening in the housing opposite the first opening that forms a second end 111, 211 of the passage 102, 202. The passage defines an axis A and forms a guide portion of the linear bearing 103, 203. Preferably, the passage has a cylindrical shape.

[0049] The placement head 100, 200 further includes a rigid handling device 104, 204 through which the placement head 100, 200 interacts with a part (e.g., via a nozzle). The rigid handling device 104, 204 includes a shaft portion 105, 205 partially received within the passageway 102, 202 and having a first end 106, 206 extending from a first end 107, 207 of the passageway 102, 202. The shaft portion 105, 205 is configured to move along the passageway 102, 202 and forms the moving portion of the linear bearing 103, 203.

[0050] The linear bearing formed by the passages 102, 202 and the shaft portions 105, 205 may be configured to form a gas bearing (e.g., air). In such an embodiment, the housing 101, 201 may include a porous substrate 121, 221, 222 lining at least a portion of the passages 102, 202 and forming a chamber between the housing 101, 201 and the porous substrate 121, 221, 222. The substrate may include a naturally porous material or a material that has been made porous, for example, by some perforation method. The housing may further include a gas inlet 120, 220 configured to supply gas to the chamber, thereby allowing the supplied gas to be evenly distributed throughout the gas bearing. The supplied gas may be exhausted from the gas bearing via the first end 107, 207 and the second end 111, 211 of the passages 102, 202. As an alternative to gas bearings, the linear bearings may include other types of guiding means (e.g., linear and / or rotary), such as leaf springs (flexures), ball bearings, ball guides, etc. For example, the passages 102, 202 may include at least one leaf spring for guiding the shaft portions 105, 205.

[0051] Typically, the first end 106, 206 of the shaft portion 105, 205 is configured to receive a nozzle suitable for holding a part. To this end, the shaft portion 105, 205 may include a suction passage extending toward the first end 106, 206 of the shaft portion 105, 205. For example, the shaft portion 105, 205 may include a through hole arranged parallel to the axis A and configured to form the suction passage.

[0052] The shaft portion 105, 205 has a second end 112, 212 disposed opposite the first end 106, 206. The second end 112, 212 of the shaft portion 105, 205 extends from the second end 111, 211 of the passageway 102, 202. However, in other embodiments, the second end 112, 212 of the shaft portion 105, 205 does not extend from the (optional) second end 111, 211 of the passageway 102, 202.

[0053] End plates 118, 218 are connected to second ends 112, 212 of shaft portions 105, 205. End plates 118, 218 are configured to form end stops for shaft portions 105, 205 moving in first direction B along passageways 102, 202. The housing may include thrust bearings (e.g., ball bearings, air bearings) disposed between the housing and the end plates, which allow the shaft portions to rotate with low friction relative to the housing.

[0054] The placement head 100, 200 further comprises a blocking means 108, 208. The blocking means 108, 208 includes a first resilient element 109, 209 configured to generate a first force that biases the first end 106, 206 of the shaft portion 105, 205 in a first direction B generally parallel to the axis, away from the first end 107, 207 of the passageway 102, 202. The blocking means 108, 208 may be configured to actively control the first force, for example, by actively controlling the stiffness of the first resilient element 109, 209, thereby actively controlling the total stiffness of the first resilient element 109, 209 and its contribution to the total biasing force. For example, the first resilient element 109, 209 may comprise a first pressure chamber, and the blocking means 108, 208 may be configured to control the pressure within the first pressure chamber 109, 209. To this end, the control device may include a conduit 119, 219 forming a gas inlet and / or a gas outlet configured to control the pressure in the first pressure chamber.

[0055] The first pressure chamber 109 may be spaced apart from the linear bearing. In one example (see FIGS. 1A and 1B ), the first pressure chamber 109 includes a bellows disposed on an end plate 118 facing away from the second end 112 of the shaft portion 105. The end plate 118 abuts the first end of the bellows. The second end of the bellows, located opposite the first end of the bellows, is preferably (fixedly) connected to the housing 101, for example, via a bracket 131 fixedly connected to the housing 101 or forming an integral part of the housing 101. The bracket 131 may form a joint configured to connect the housing 101 to the stage. The pressure within the bellows can be controlled by supplying and / or exhausting gas via a conduit 119.

[0056] Alternatively, the linear bearing may be configured to form a first pressure chamber. For example, the cross-sectional area of ​​the linear bearing varies along axis A, forming a pocket (e.g., an air pocket) between the passageway and the shaft portion, the pocket forming the first pressure chamber. In one example (see FIGS. 2A and 2B ), housing 201 includes a passageway, where first portion 213 of passageway 202 has a first diameter and second portion 214 of passageway 202 has a second diameter greater than the first diameter. Further, shaft portion 205 includes first portion 215 having a third diameter, where first portion 215 overlaps first portion 213 of passageway 202, and shaft portion 205 includes second portion 216 having a fourth diameter, where second portion 216 overlaps second portion 214 of passageway 202. The third and fourth diameters correspond to the first and second diameters, respectively, and may form a linear bearing with the passageway 202 and shaft portion 205. The pressure within the pocket may be controlled by supplying and / or venting gas via the conduit 219 and / or the gas inlet 220.

[0057] In either of the two previous embodiments, supplying gas to the first pressure chamber 109, 209 increases the pressure in the first pressure chamber, which biases the rigid handling element 104, 204 in the first direction B relative to the housing 101, 201, increasing the rigidity of the placement head 100, 200.

[0058] The placement head may include a second elastic element, such as a second spring or a second pressure chamber (e.g., a second bellows), to generate a second force biasing the first end of the shaft portion 205 in a first direction away from the first end of the passageway. Such a second elastic element may be located away from the linear bearing. In one example (see FIGS. 2 and 2B ), the second elastic element includes a bellows 217 located on a side of an end plate 218 facing away from the second end 212 of the shaft portion 205. The end plate 218 abuts the first end of the bellows 217. The second end of the bellows 217, located opposite the first end of the bellows 217, is preferably (fixedly) connected to the housing 201, for example, via a bracket 231 fixedly connected to the housing 201 or forming an integral part of the housing 201. The bracket 231 may form a joint configured to connect the housing 101 to the stage.

[0059] The placement head 100, 200 further comprises a detection device 132, 232 configured to detect a magnitude of movement C of the rigid handling device 104, 204 relative to the housing 101, 201 generally parallel to the axis A. For example, the detection device may comprise a sensor (e.g., a magnetic, capacitive, or optical sensor) connected to the housing and configured to detect a magnitude of movement of the end plate 118, 218.

[0060] 1A and 2A, in the locked state, the pressure within the first resilient element 109, 209 increases to the extent that the end plate 118, 218 is forced into abutment against the housing 101, 201. The end plate 118, 218 in this state forms an end stop that prevents the shaft portion 105, 205 from further movement along the passageway 102, 202 in the first direction. In this state, the shaft portion 105, 205 extends maximally from the first end 107, 207 of the passageway 102, 202. This locked state is used when the placement head is moved during a transfer phase, which is associated with high speeds of movement and, more importantly, high accelerations and decelerations. The pressure is typically selected so that the end plate 118, 218 remains in abutment against the housing 101, 201 during the transfer phase.

[0061] 1B and 2B, in the released state, the end plates 118, 218 can move away from the housing 101, 201, allowing the shaft portions 105, 205 to move along the passages 102, 202 in a second direction opposite the first direction. This movement of the shaft portions 105, 205 relative to the passages 102, 202 compresses the first elastic elements 109, 209. This released state is used when the placement head is moved during the pick-and-place phase, which is associated with slow movement, and more importantly, low acceleration and reduced velocity. When the rigid handling device impacts an external surface (e.g., the surface of a PCB via a component), the shaft portions 105, 205 move along the passages 102, 202 in the second direction opposite the first direction. The resulting magnitude of the displacement C, combined with the controlled stiffness and optionally any additional stiffness introduced, for example, by a second elastic element, forms a measure of the force (e.g., placement force) applied to the exterior surface. Figures 2A and 2B show the placement head at a situation where the magnitude of displacement is at its maximum.

[0062] 3A and 3B, a placement head 300, similar to the placement head shown in FIGS. 2A and 2B, is connected to a stage 331, which together form (part of) a manipulator 323. The housing 301 is fixedly connected to the stage 331 via a first joint of the stage 331. The stage 331 further comprises a second joint comprising a rotary actuator 330 connected to a shaft portion 305 via a (rigid) conduit 328 and a second elastic element 317. The stage 331 is typically moved within the volume using multiple linear actuators (not shown). A component 325 can be placed on the PCB 324 by moving the placement head 300 in a first direction toward the PCB 324.

[0063] A (flexible) conduit 329 provided inside the second elastic element 317 fluidly connects the (rigid) conduit 328 to a suction passage 327 provided in the shaft portion 305. A first end of the shaft portion 305 is connected to a nozzle 326 configured to pick up and hold the component 325 using gas pressure (e.g., vacuum) applied to the (rigid) conduit 328, for example, by a pneumatic system (not shown), and to place the component 325 onto the PCB 324 using gas pressure (e.g., compressed air) applied to the (rigid) conduit 328, for example, by a pneumatic system (not shown).

[0064] A detector 332 is attached to the stage and is configured to detect the magnitude of movement of the end plate 318 of the shaft portion 305 relative to the stage, and thus directly detects the magnitude of movement of the shaft portion 305 relative to the housing.

[0065] During the transfer phase (see FIG. 3A), the component is still relatively far away from the PCB. At this phase, the blocking means is in a blocking state. In this state, the relative position of the rigid handling element to the housing is locked by generating a high pressure in the first elastic element. Locking this relative position allows the stage 331 to be moved with high acceleration.

[0066] The pick-and-place phase begins when component 325 approaches PCB 324 (see FIG. 3B). During this phase, the blocking means is in a released state. In this state, the rigid handling element can move relative to the housing by reducing (or preferably releasing) the pressure in the first elastic element. During this phase, the acceleration of stage 331 is limited to prevent damage to component 325 and / or placement head 300. The acceleration is preferably limited to prevent the shaft from moving relative to the housing as a result of the acceleration. This can be achieved by limiting the acceleration so that the force generated does not exceed the force that keeps the shaft in place relative to the housing, which force may be generated, for example, by the blocking means, second elastic element 317, gravity, and / or inertia.

[0067] When contact occurs between component 325 and PCB 324 (see FIG. 3C), shaft portion 305 is displaced relative to housing 301 in a direction opposite to the first direction (see FIG. 3B). As a result, end plate 318 is displaced relative to sensing device 332 and the resilient element is compressed accordingly, resulting in a movement that is directly related to the deployment force. Thus, detecting the movement with sensing device 332 allows for precise control of the deployment force.

Claims

1. A placement head (100, 200, 300) for a pick and place device, comprising: a housing (101, 201, 301) having a passage (102, 202) defining an axis (A); a rigid handling device (104, 204), a shaft portion (105, 205, 305) partially received within the passageway, the housing and the shaft portion collectively defining a linear bearing (103, 203), the shaft portion configured to move along the passageway generally parallel to the axis, a first end (106, 206) of the shaft portion extending from a first end (107, 207) of the passageway; the first end of the shaft portion is configured to receive a nozzle (326) suitable for holding a part (325); a rigid handling device; a first elastic element (109, 209) configured to generate a first force between the housing and the rigid handling device, the first elastic element being configured to generate a first force in a first direction (B) substantially parallel to the axis, urging the first end of the shaft portion away from the first end of the passage; - blocking means (108, 208, 308) configured to releasably block said first end of said shaft portion from moving in a second direction opposite said first direction (B) towards said first end of said passage; a detection device (132, 232, 332) configured to detect the magnitude of a movement (C) of said rigid handling device relative to said housing substantially parallel to said axis, Preferably, the linear bearing is configured to form a gas bearing.

2. 2. The placement head of claim 1, wherein the blocking means comprises the first resilient element (109, 209), the blocking means being configured to adapt at least one of an offset force biasing the first end of the shaft portion away from the first end of the passage in a first direction and a stiffness of the first resilient element.

3. 3. A placement head as claimed in claim 2, wherein the first resilient element comprises a first pressure chamber and the preventing means is configured to control the pressure in the first pressure chamber, preferably the preventing means is configured to supply gas to the linear bearing.

4. The passage (202) has a second end (211) opposite to the first end (207) of the passage, the shaft portion (205) has a second end (212) opposite to the first end (206) of the shaft portion, the passage having a first portion (213) extending toward the first end of the passage and having a first diameter, and a second portion (214) extending toward the second end of the passage and having a second diameter, the shaft portion 4. The placement head of claim 1, further comprising: a first portion (215) extending toward a second end of the shaft portion and having a third diameter related to the first diameter; and a second portion extending toward a second end of the shaft portion and having a fourth diameter related to the second diameter, wherein the passageway and the shaft portion are configured to define a first pressure chamber between a first interface of the first and second portions of the passageway and a second interface of the first and second portions of the shaft portion.

5. The placement head of claim 4 , wherein the first diameter is greater than the second diameter.

6. 6. The placement head of any one of claims 1 to 5, further comprising a second elastic element (217, 317), wherein the second elastic element is configured to generate a second force biasing the first end of the shaft portion in the first direction (B), preferably wherein the second elastic element is configured to passively generate the second force, preferably wherein the second force is related to the magnitude of the movement, preferably wherein the second force is proportional to the magnitude of the movement.

7. The placement head of claim 6 , wherein the second resilient element is at least one of a spring and a second pressure chamber.

8. 8. The placement head of claim 1, wherein the first elastic element is connected to the housing via a first end of the first elastic element, and the first elastic element is connected to the shaft portion via a second end of the first elastic element arranged opposite the first end of the first elastic element.

9. 9. The placement head of claim 1, wherein the passage has a second end opposite the first end of the passage, the shaft portion has a second end opposite the first end of the shaft portion, the second end of the shaft portion extending from the second end of the passage, the rigid handling device further comprising an end plate (118, 218, 318) extending from and connected to the second end of the shaft portion, the detection device being configured to directly detect a magnitude of movement of the end plate relative to the housing, preferably the end plate abutting at least one of the second end of the first elastic element and the end of the second elastic element.

10. 10. A manipulator for a pick and place apparatus comprising a placement head according to any one of claims 1 to 9, a base, and actuation means connected at a first end to the base and at a second end to the placement head, the actuation means configured to move the placement head relative to the base.

11. 11. The manipulator of claim 10, further comprising a control unit connected to the preventing means, the control unit configured to control the preventing means between a blocked state in which the shaft portion is blocked from moving relative to the housing and a released state in which the shaft portion is released for movement relative to the housing parallel to the axis.

12. 12. The manipulator of claim 11, wherein the control unit is configured to control the actuation means during a transfer stage in which the placement head is transferred between a pick location and a place location, and a pick-and-place stage in which the placement head performs one of picking and placing a component at the pick location and the place location, respectively, and wherein the control unit is further configured to maintain the blocked state during the transfer stage and to maintain the released state during the pick-and-place stage.

13. 13. A manipulator as described in claim 11 or 12, wherein the control unit is further connected to the detection device and is configured to stop movement of the placement head in the first direction when the magnitude of the movement reaches a predetermined threshold, preferably wherein the second end of the actuation means includes a stage connected to the placement head and the control unit is configured to stop movement of the stage in the first direction during the pick and place phase.

14. A pick-and-place apparatus comprising a placement head according to any one of claims 1 to 9 or a manipulator according to any one of claims 10 to 13.

15. A method for placing a component using a placement head as claimed in any one of claims 1 to 9, a manipulator as claimed in any one of claims 10 to 13, or a pick and place apparatus as claimed in claim 14, comprising the steps of: activating the blocking means to prevent the shaft portion from moving relative to the housing during a transfer phase in which the placement head moves between a pick position and a place position; and activating the blocking means to release the shaft portion to allow it to move along the pathway during a pick and place phase in which the placement head performs one of picking and placing a component at the pick position and the place position, respectively.

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