Tape laying head
A tape laying head configured to lay a tow material on a mould in the construction of a composite structure, the tape laying head including: a shearing mechanism configured to receive tow material from a tow supply and to steer the tow material by applying shear deformation to the tow material between a pair of shear boundaries defined by the shearing mechanism, the shearing mechanism being further configured to apply a driving force to the tow material, the driving force having a longitudinal component and a transverse component with respect to the tow material during steering of the tow material; and a tension control system configured to control the transverse component of the driving force acting on the tow material to be equal to or less than a maximum transverse frictional force associated with the shearing mechanism by varying a tensioning force applied to the tow material by the tension control system and monitoring the driving force.
1 . A tape laying head configured to lay a tow material on a mould in the construction of a composite structure, the tape laying head including:
a shearing mechanism including a compaction shoe or roller and a gripping shoe or roller, the shearing mechanism configured to receive tow material from a tow supply and to steer the tow material with respect to the mould by applying shear deformation to the tow material between a pair of shear boundaries defined by the shearing mechanism, wherein at least a first of the pair of shear boundaries is defined by the compaction shoe or roller and a second of the pair of shear boundaries is defined by the gripping shoe or roller, the shearing mechanism including a force generator being further configured to apply a driving force to the tow material, the driving force having a longitudinal component and a transverse component with respect to the tow material during steering of the tow material; and
a tension control system including a controller and a first sensor to generate a first sensor signal representative of a tension of the tow material between the tow supply and the shearing mechanism, the controller being configured, using the first sensor signal, to control the transverse component of the driving force acting on the tow material to be equal to or less than a maximum transverse frictional force associated with the shearing mechanism, during steering of the tow material with respect to the mould using the shearing mechanism to apply shear deformation to the tow material with the compaction shoe or roller pressing the tow material onto the mould, by varying a tensioning force applied to the tow material by the tension control system and monitoring the driving force.
2 . The tape laying head according to claim 1 , wherein the first sensor includes a first load sensor configured to generate a first load sensor signal representative of the tension of the tow material between the tow supply and the shearing mechanism, wherein the first load sensor signal is used in monitoring the driving force.
3 . The tape laying head according to claim 1 , wherein the tow material is provided with a backing material, the shearing mechanism is configured to separate the tow material from the backing material, and the tension control system further includes a second sensor configured to generate a second sensor signal representative of a tension of the backing material between the shearing mechanism and a backing material collector, the second sensor signal being used in monitoring the driving force.
4 . The tape laying head according to claim 3 , wherein the shearing mechanism further includes a tow guide roller, and the tension control system further includes a first motor configured to drive rotation of the tow guide roller, the tensioning force being at least partially applied by the first motor.
5 . The tape laying head according to claim 4 , wherein the tension control system further includes a second motor configured to drive operation of the backing material collector, the tensioning force being at least partially applied by the second motor.
6 . The tape laying head according to claim 3 , wherein the tension control system further includes a brake associated with the tow supply and configured to brake the delivery of tow material from the tow supply to the shearing mechanism, the tensioning force being at least partially applied by the brake.
7 . The tape laying head according to claim 1 , wherein the first of the pair of shear boundaries is defined by a contact point between the compaction shoe or roller and the mould in normal operation and the second of the pair of shear boundaries is defined by a contact point between the compaction shoe or roller and the gripping shoe or roller.
8 . The tape laying head according to claim 1 , further including a web mechanism wherein the tow material is provided with a web prior to shear deformation of the tow material and the web mechanism is configured to remove the web from the tow material after the tow material has been laid on the mould.
9 . The tape laying head according to claim 8 , wherein the web mechanism is further configured to add the web to the tow material prior to shear deformation of the tow material.
10 . The tape laying head according to claim 9 , wherein the web mechanism includes a source of web material and a web material collector associated with a motor, the motor being configured to operate the web material collector to pull the web from the source of web material.
11 . The tape laying head according to claim 1 , further including:
a source of tow material and/or a backing material collector; and
a slip compensation mechanism configured to move the shearing mechanism laterally with respect to the source of tow material and/or the backing material collector, such that lateral slip of the tow material is compensated.
12 . The tape laying head according to claim 11 , wherein the slip compensation mechanism includes:
one or more rails configured to enable movement with respect to a part of the head of one or more of: the shearing mechanism, or a tow guide roller and the gripping shoe or roller; and
a driving arrangement to drive movement of the shearing mechanism, or the tow guide roller and the gripping shoe or roller.
13 . The tape laying head according to claim 11 , wherein the slip compensation mechanism further includes a further sensor configured to sense lateral slip of the tow material.
14 . The tape laying head according to claim 1 , wherein the tension control system is further configured to keep the driving force above a minimum threshold by varying the tensioning force.
15 . The tape laying head according to claim 1 , wherein the tow material is a pre-impregnated tow material.
16 . The tape laying head according to claim 1 , wherein the controller is configured to vary the tensioning force applied to the tow material based in part on a shear angle of the tow material during the steering of the tow material.
17 . A tape laying system including:
a controller for use in a tension control system of the tape laying system, and
a shearing mechanism including a compaction shoe or roller and a gripping shoe or roller, the shearing mechanism configured to receive tow material from a tow supply and to steer the tow material with respect to a mould by applying shear deformation to the tow material between a pair of shear boundaries defined by the shearing mechanism, wherein at least a first of the pair of shear boundaries is defined by the compaction shoe or roller and a second of the pair of shear boundaries is defined by the gripping shoe or roller, the shearing mechanism including a force generator configured to apply a driving force to the tow material, the driving force having a longitudinal component and a transverse component with respect to the tow material during steering of the tow material,
wherein the controller is configured to receive a first sensor signal from a first sensor, the first sensor signal being representative of a tension of the tow material between the tow supply and the shearing mechanism, and to control, using the first sensor signal, the transverse component of the driving force acting on the tow material to be equal to or less than a maximum transverse frictional force associated with the shearing mechanism, during steering of the tow material with respect to the mould using the shearing mechanism to apply shear deformation to the tow material with the compaction shoe or roller pressing the tow material onto the mould, by causing variation in a tensioning force applied to the tow material and monitoring the driving force.
18 . The tape laying system according to claim 17 , wherein the first sensor is a first load sensor that creates a first load sensor signal representative of the tension of the tow material between the tow supply and the shearing mechanism, the first load sensor signal being used by the controller in monitoring the driving force.
19 . The tape laying system according to claim 17 , wherein the tow material is provided with a backing material and the shearing mechanism is configured to separate the tow material from the backing material, the controller being further configured to receive a second sensor signal representative of a tension of the backing material between the shearing mechanism and a backing material collector, the second sensor signal being used by the controller in monitoring the driving force.
20 . The tape laying system according to claim 19 , wherein the controller is further configured to output a first motor signal, the shearing mechanism further includes a tow guide roller, and a first motor drives rotation of the tow guide roller, the first motor signal controlling operation of the first motor and the tensioning force being at least partially applied by the first motor.
21 . The tape laying system according to claim 20 , wherein the controller is further configured to output a second motor signal, a second motor drives operation of the backing material collector, the second motor signal controlling operation of the second motor and the tensioning force being at least partially applied by the second motor.
22 . The tape laying system according to claim 19 , wherein a brake is associated with the tow supply and is configured to brake the delivery of tow material from the tow supply to the shearing mechanism, the controller being configured to generate a brake signal to control the brake and the tensioning force being at least partially applied by the brake.
23 . The tape laying system according to claim 17 , wherein the controller is further configured to keep the driving force above a minimum threshold by varying the tensioning force.
24 . The tape laying system according to claim 17 , wherein the tape laying system further includes a web mechanism, the tow material being provided with a web prior to shear deformation of the tow material and the controller is further configured to operate the web mechanism to remove the web from the tow material after the tow material has been laid on the mould.
25 . The tape laying system according to claim 24 , wherein the controller is further configured to operate the web mechanism to add the web to the tow material prior to shear deformation of the tow material.
26 . The tape laying system according to claim 25 , wherein the web mechanism includes a source of web material and a web material collector associated with a motor, the controller being further configured to operate the motor to pull the web from the source of web material.
27 . The tape laying system according to claim 17 , including:
a source of tow material and/or a backing material collector, and
a slip compensation mechanism; and
wherein the controller is further configured to operate the slip compensation mechanism to move the shearing mechanism laterally with respect to the source of tow material and/or the backing material collector, such that lateral slip of the tow material is compensated.
28 . The tape laying system according to claim 27 , wherein the slip compensation mechanism includes:
one or more rails configured to enable movement with respect to a part of the system of one or more of: the shearing mechanism, or a tow guide roller and the gripping shoe or roller; and
a driving arrangement, wherein the controller is configured to operate the driving arrangement to drive movement of the shearing mechanism, or the tow guide roller and the gripping shoe or roller.
29 . The tape laying system according to claim 27 , wherein the controller is further configured to receive a further signal from a further sensor, the further signal being indicative of lateral slip of the tow material.
30 . The tape laying system according to claim 17 , wherein the controller is configured to vary the tensioning force applied to the tow material based in part on a shear angle of the tow material during the steering of the tow material.
31 . A control method for use in a tension control system of a tape laying system, the tape laying system including a shearing mechanism including a compaction shoe or roller and a gripping shoe or roller, the shearing mechanism configured to receive tow material from a tow supply and to steer the tow material with respect to a mould by applying shear deformation to the tow material between a pair of shear boundaries defined by the shearing mechanism, wherein at least a first of the pair of shear boundaries is defined by the compaction shoe or roller and a second of the pair of shear boundaries is defined by the gripping shoe or roller, the shearing mechanism being further configured to apply a driving force to the tow material, the driving force having a longitudinal component and a transverse component with respect to the tow material during steering of the tow material, the method including:
providing tow material from the tow supply to the shearing mechanism;
pressing the tow material onto the mould using the compaction shoe or roller;
steering the tow material with respect to the mould using the shearing mechanism to apply shear deformation to the tow material with the compaction shoe or roller pressing the tow material onto the mould;
receiving a first sensor signal from a first sensor, the first sensor signal being representative of a tension of the tow material between the tow supply and the shearing mechanism, and
controlling, using the first sensor signal, the transverse component of the driving force acting on the tow material to be equal to or less than a maximum transverse frictional force associated with the shearing mechanism, during steering of the tow material using the shearing mechanism, by causing variation in a tensioning force applied to the tow material and monitoring the driving force.
32 . The control method according to claim 31 , wherein varying the tensioning force applied to the tow material is based in part on a shear angle of the tow material during the steering of the tow material.