Patent Publication Number: US-11654475-B2

Title: Rivet setting tool

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 63/033,900, filed on Jun. 3, 2020, the entire content of which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to rivet setting tools, and more particularly to pulling mechanisms for rivet setting tools. 
     BACKGROUND 
     Rivet setting tools use pulling mechanisms to pull a mandrel of a rivet to set a rivet. Pulling mechanisms sometimes have pulling members that move between a first position, in which the mandrel is ready to be received in the pulling mechanism, and a second position, in which the mandrel has been separated from the rivet, such that the pulling member can return to the first position. 
     SUMMARY 
     The present disclosure provides, in one aspect, a rivet tool for setting a rivet. The rivet tool includes a motor and a pulling mechanism configured to receive torque from the motor. The pulling mechanism includes a moveable member that is moveable between a first position and a second position in response to the pulling mechanism receiving torque from the motor, a plurality of jaws configured to clamp onto a mandrel of the rivet and pull the mandrel in response to the moveable member moving from the first position to the second position, and a magnet coupled for movement with the moveable member. The magnet includes a north pole face, an adjacent south pole face, and a pole junction therebetween. The north and south pole faces face away from the moveable member. The rivet tool further comprises a first sensor configured to detect the pole junction when the moveable member is in the first position and a second sensor configured to detect the pole junction when the moveable member is in the second position. 
     In some implementations, the north pole face and the south pole face are coplanar. 
     In some implementations, the magnet is moveable along a face plane defined by the north pole face and the south pole face. 
     In some implementations, the face plane is parallel to a pulling axis along which the moveable member moves between the first and second positions. 
     In some implementations, the second sensor is a north pole-detecting Hall-effect sensor. When the moveable member moves to the second position, the second sensor is configured to output a signal to a controller indicating that a north pole flux detected by the second sensor is zero. 
     In some implementations, in response to the controller receiving the signal from the second sensor indicating that north pole flux detected by the second sensor is zero, the controller is configured to deactivate the motor. 
     In some implementations, the first sensor is a south pole-detecting Hall-effect sensor. When the moveable member moves to the first position, the first sensor is configured to output a signal to the controller indicating that a south pole flux detected by the first sensor is zero. 
     In some implementations, in response to the controller receiving the signal from the first sensor indicating that south pole flux detected by the first sensor is zero, the controller is configured to deactivate the motor. 
     In another aspect, the disclosure provides a rivet tool for setting a rivet. The rivet tool includes a motor, and a pulling mechanism configured to receive torque from the motor and pull the rivet. The pulling mechanism includes a moveable member that is moveable between a first position and a second position in response to the pulling mechanism receiving torque from the motor. The pulling mechanism also includes a magnet coupled for movement with the moveable member, the magnet including a north pole face, an adjacent south pole face, and a pole junction therebetween. The rivet tool also includes a sensor configured to detect the pole junction when the moveable member is in the first position. 
     In yet another aspect, the disclosure provides a power tool including a motor, a moveable member that is moveable between a first position and a second position in response to receiving torque from the motor, and a magnet coupled for movement with the moveable member. The magnet includes a north pole face, an adjacent south pole face, and a pole junction therebetween. The power tool also includes a sensor configured to detect the pole junction when the moveable member is in the first position, and a controller configured to deactivate the motor based on a position of the pole junction detected by the sensor. 
     Other features and aspects of the disclosure will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a rivet setting tool. 
         FIG.  2    is a cross-sectional view of the rivet setting tool of  FIG.  1   . 
         FIG.  3    is a partial cross-sectional view of a jaw sleeve of the rivet setting tool of  FIG.  1   . 
         FIG.  4    is a perspective view of the rivet setting tool of  FIG.  1   , with portions removed. 
         FIG.  5    is an enlarged cross-sectional view of the rivet setting tool of  FIG.  1   . 
         FIG.  6    is a plan view of a magnet of the rivet setting tool of  FIG.  1   . 
         FIG.  7    is an elevation view of a magnet of the rivet setting tool of  FIG.  1   . 
     
    
    
     Before any implementations of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other implementations and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION 
     With reference to  FIGS.  1  and  2   , a rivet setting tool  10 , such as a blind rivet setting tool, a rivet nut setting tool, or other deformable fastener setting tools, includes an electric motor  12  and a transmission  14  (e.g., a multi-stage planetary transmission) that receives torque from the motor  12 . The tool  10  also includes a pulling mechanism  18  that is actuated in response to activation of the motor  12  to initiate a rivet setting process. In the illustrated implementation, the rivet setting tool  10  includes a battery pack  20  for providing power to the motor  12 . In other implementations, the rivet setting tool  10  may include an electrical cord for connection to a remote power source (e.g., an alternating current source). 
     With reference to  FIG.  2   , the tool  10  includes a housing  22  in which the pulling mechanism  18  is positioned and arranged along a pulling axis  26  along which a rivet is pulled. For example, the rivet may include a mandrel that is pulled, or may include a rivet nut or other deformable fastener in other implementations. The pulling mechanism  18  includes a ball nut  30  that receives torque from a gear  34  of the transmission  14 , and a pulling member, such as a ball screw  38 , arranged within the pulling head  30 . A plurality of rollers  42  ( FIG.  5   ) are arranged between threads  46  of the ball nut  30  and threads  50  of the ball screw  38  such that in response to rotation of the ball nut  30  about the pulling axis  26 , the rollers  42  facilitate smooth axial movement of the ball screw  38  between a first position and a second position, as explained in further detail below. 
     With reference to  FIG.  2   , the pulling mechanism  18  also includes a jaw sleeve  54  that is coupled to the ball screw  38  for movement therewith. With reference to  FIG.  3   , the jaw sleeve  54  includes a plurality of interior recesses  58  that are obliquely oriented with respect to the pulling axis  26 , converging in a direction away from the ball screw  38 . The pulling mechanism  18  also includes a plurality of jaws  62  ( FIG.  2   ), with each jaw  62  respectively arranged within each of the recesses  58 . The jaws  62  are biased away from the ball screw  38  by a jaw pusher  66 , which is in turn biased away from the ball screw  38  by a compression spring  70  that is arranged within the jaw sleeve  54  and seated against the ball screw  38 . A spent-mandrel tube  74  extends along the pulling axis  26  through the jaw pusher  66 , the compression spring  70 , and the ball screw  38 , terminating in a mandrel container  78  to collect severed mandrels after a rivet-setting operation has been completed. A nosepiece  82  is coupled to the housing  22  at an end opposite the mandrel container  78 . 
     With reference to  FIGS.  2 ,  4 , and  5   , a carrier  86  is coupled to the ball screw  38  and includes a pair of oppositely extending posts  90  on which a pair of rollers  94  are respectively arranged ( FIG.  4   ). Each roller  94  is respectively arranged and configured to roll between a pair of rails  98 . The carrier  86  is rotationally affixed to the ball screw  38  and prevents the ball screw  38  from rotating about the pulling axis  26  in response to rotation of the ball nut  30 . Specifically, because the rollers  94  supported by the carrier  86  are confined between the rails  98 , in response to rotation of the ball nut  30 , the ball screw  38  is inhibited from rotating, and is instead limited to a single degree of freedom (i.e., translation along the pulling axis  26 ) between a first, home position, in which a mandrel of the rivet may be set in the jaws  62 , and a second, complete position, in which the mandrel has been severed from the rivet and the setting operation is complete. 
     With continued reference to  FIGS.  2 ,  4 , and  5   , a magnet  102  is supported upon the carrier  86  and is covered by a magnet cover  106 . With reference to  FIG.  6   , the magnet  102  includes a North pole face  110  and an adjacent South pole face  114 . The North pole face  110  is separated from the South pole face  114  by a pole junction (indicated by plane P D ) that is perpendicular to the pulling axis  26 . As shown in  FIG.  5   , in the illustrated implementation, the north and South pole faces  110 ,  114  are coplanar, with the north and South pole faces  110 ,  114  collectively defining a face plane P F  ( FIG.  5   ) that is parallel to the pulling axis  26 . As also shown in  FIG.  5   , both of the north and South pole faces  110 ,  114  face away from the ball screw  38  and both of the north and South pole faces  110 ,  114  are in facing relationship with a printed circuit board (PCB)  120  that is parallel to the pulling axis  26 . As shown in  FIG.  7   , the magnet  102  includes a second South pole face  118  on a side of the magnet  102  opposite the North pole face  110  and a second North pole face  120  on the side of the magnet  102  opposite the South pole face  114 . 
     When the ball screw  38  is in the first position, the magnet  102  is proximate a first sensor  122  on the PCB  120 . As described in further detail below, the first sensor  122  is configured to detect presence of the magnet  102  when the ball screw  38  is in the first position. When the ball screw  38  is in the second position, the magnet  102  is proximate a second sensor  126  on the PCB  120 . As described in further detail below, the second sensor  126  is configured to detect presence of the magnet  102  when the ball screw  38  is in the second position. In the illustrated implementation, the first and second sensors  122 ,  126  are Hall-effect sensors. 
     In operation, an operator inserts a mandrel of a rivet through the nosepiece  82 . The mandrel initially pushes the jaws  62  away from the nosepiece  82 , along their respective recesses  68 , until the jaws  62  move far enough away from the pulling axis  26  that the mandrel moves between the jaws  62 . The jaws  62 , biased by the jaw pusher  66  toward the nosepiece  82 , thereafter exert a radial clamping force on the mandrel. The operator then pulls a trigger  130  on the tool  10  to rotate the motor  12  in a first rotational direction, which causes the transmission  14  to rotate the gear  34 , thus causing the ball nut  30  to rotate. Rotation of the ball nut  30  causes the ball screw  38  to translate from the first position toward the second position (toward the right in the frame of reference of  FIG.  5   ). As the ball screw  38  translates from the first position toward the second position, the jaw sleeve  54  is also drawn away from the nosepiece  82  in unison with the ball screw  38 , causing the mandrel to be drawn, via the clamped jaws  54 , away from the nosepiece  82 . As the ball screw  38  continues to move toward the second position, the rivet is eventually set on the workpiece and the mandrel is severed prior to or upon the ball screw  38  reaching the second position. As noted above, when the ball screw  38  reaches the second position, the second sensor  126  detects that the magnet  102  is proximate the second sensor  126 . 
     The second sensor  126  detects when the ball screw  38  has reached the second position because the magnet  102  includes adjacent North pole and South pole faces  110 ,  114 . Specifically, in the illustrated implementation, the second sensor  126  is a North pole-detecting Hall-effect sensor and is configured to output a signal indicative of detected North pole magnetic flux to a controller  134  (shown schematically in  FIG.  5   ). As the magnet  102  translates with the ball screw  38  toward the second sensor  126 , the second sensor  126  first detects the North pole magnetic flux from the North pole face  110 , prior to the ball screw  38  reaching the second position. 
     When the ball screw  38  reaches the second position, the second sensor  126  detects that the pole junction P D  has reached a second signaling position with respect to the second sensor  126 . Specifically, the second sensor  126  detects that the pole junction P D  has reached the second signaling position because the detected North pole flux drops to 0, due to the South pole magnetic flux from the South pole face  114  canceling out the North pole magnetic flux from the North pole face  110 . In some implementations, the second signaling position is defined by the position of the magnet  102  when the pole junction P D  intersects a center  138  of the second sensor  126 . In other implementations, the second signaling position is defined by the position of the magnet  102  when the pole junction P D  is offset from the center  138  of the second sensor  126 , taking into account the following factors: (1) timing of the signal sent from the second sensor  126  to the controller  134 ; (2) electronic logic delay of the controller  134  to interpret the signal received from the second sensor  126  to determine that the ball screw  38  has reached the second position; and (3) the speed of movement of the ball screw  38  as it travels toward the second position. 
     In response to the second sensor  126  outputting a signal to the controller  134  that indicates that the detected North pole flux has dropped to zero, the controller  134  stops rotation of the motor  12 , thus stopping movement of the ball screw  38  in the second position. The broken mandrel is now free to slide through the spent-mandrel tube  74  for collection in the mandrel container  78 . In contrast to including a magnet with a single-pole face (e.g., a North pole) in facing relationship with the PCB  120  and Hall-effect sensors  122 ,  126 , because the magnet  102  has a North pole face  110  and South pole face  114  in facing relationship with the PCB  118 , the second sensor  126  is able to more precisely detect when the ball screw  38  has reached the second position by detecting when the North pole flux has dropped to zero. Hall-effect sensors detecting a single-pole face of a magnet are more susceptible to variation of detected magnetic flux based on the distance separating the single-pole face magnet from the Hall-effect sensor. By more precisely determining when the ball screw  38  has reached the second position, potential damage to the pulling mechanism due to overtravel, i.e., traveling past the second position after the mandrel has been severed from the rivet, is reduced. 
     In other implementations, the second sensor  126  is a South pole detecting Hall-effect sensor and the controller  134  is able to determine that the ball screw  38  has reached the second position when the controller  134  receives a signal from the second sensor  126  indicating that detected South pole flux increases from zero to a non-zero value. Specifically, as the North pole face  110  approaches the South pole detecting Hall-effect second sensor  126 , the second sensor  126  does not detect any South pole flux and thus, the detected value is zero. However, as the pole junction P D  has reached the second signaling position, the second sensor  126  for the first time detects the South pole flux from the South pole face  114 . Upon the controller  134  receiving a signal from the second sensor  126  indicating that detected South pole has increased from zero to a non-zero value, the controller  134  instructs the motor  18  to deactivate. 
     After stopping the motor  12 , the controller  134  subsequently causes the motor  12  to rotate in a second rotational direction that is opposite the first rotational direction, causing the ball screw  38  to move from the second position back toward the first position. As noted above, when the ball screw  38  reaches the first position, the first sensor  122  detects that the magnet  102  is proximate the first sensor  122 . The first sensor  126  detects when the ball screw  38  has reached the first position (indicating that the tool  10  is ready to set another rivet) because the magnet  102  includes adjacent North pole and South pole faces  110 ,  114 . Specifically, in the illustrated implementation, the first sensor  122  is a South pole detecting Hall-effect sensor and is configured to output a signal indicative of detected South pole magnetic flux to the controller  134 . As the magnet  102  translates along the magnet axis  118  toward the first sensor  122 , the first sensor  122  first detects the South pole magnetic flux from the South pole face  114 , prior to the ball screw  38  reaching the first position. 
     When the ball screw  38  reaches the first position, the first sensor  122  detects that the pole junction P D  has reached a first signaling position with respect to the first sensor  122 . Specifically, the first sensor  122  detects that the pole junction P D  has reached the first signaling position because the detected South pole flux drops to zero, due to the North pole magnetic flux from the North pole face  110  canceling out the South pole magnetic flux from the South pole face  114 . In some implementations, the first signaling position is defined by the position of the magnet  102  when the pole junction P D  intersects a center  142  of the first sensor  122 . In other implementations, the first signaling position is defined by the position of the magnet  102  when the pole junction P D  is offset from the center  142  of the first sensor  122 , taking into account the following factors: (1) timing of the signal sent from the first sensor  122  to the controller  134 ; (2) electronic logic delay of the controller  134  to interpret the signal received from the first sensor  122  to determine that the ball screw  38  has reached the first position; and (3) the speed of movement of the ball screw  38  as it travels toward the first position. 
     In response to the first sensor  122  outputting a signal to the controller  134  that indicates that the detected South pole flux has dropped to zero, the controller  134  stops rotation of the motor  12 , thus stopping movement of the ball screw  38  in the first position. The operator is now able to start a new rivet setting operation. In contrast to using a magnet with a single-pole face (e.g. a North pole) as mentioned above, because the magnet  102  has a North pole face  110  and South pole face  114  in facing relationship with the PCB  118  with a pole junction P D  therebetween that is detected by the first sensor  122 , the first sensor  122  is able to more precisely detect when the ball screw  38  has reached the first position by detecting when the South pole flux has dropped to zero. 
     In other implementations, the first sensor  122  is a North pole detecting Hall-effect sensor and the controller  134  is able to determine that the ball screw  38  has reached the first position when the controller  134  receives a signal from the first sensor  122  indicating that North pole flux increases from zero to a non-zero value. Specifically, as the South pole face  114  approaches the North pole detecting Hall-effect first sensor  122 , the first sensor  122  does not detect any North pole flux and thus, the detected value is zero. However, as the pole junction P D  reaches the first signaling position, the first sensor  122  for the first time detects the North pole flux from the North pole face  110 . Upon the controller  134  receiving a signal from the first sensor  122  indicating that detected North pole has increased from zero to a non-zero value, the controller  134  instructs the motor  18  to deactivate, stopping the ball screw  38  in the first position. 
     It should be understood that other configurations of North and South pole faces and North and South pole detecting Hall-effect sensors may be employed in other arrangements in order to detect the pole junction P D  reaching a signaling position based on either increasing flux strength from zero or decreasing flux strength towards zero. In some implementations, the magnet may include two or more pole junctions. For example, the magnet  102  may include three, four, or any number of coplanar pole faces  110 ,  114  (e.g., alternating North and South in series along a length of the magnet  102 ) defining a pole junction P D  between each adjacent pair of coplanar poles  110 ,  114 . In such implementations with multiple pole junctions P D , Hall effect sensors  122 ,  126  having the same pole-detection capabilities (e.g., both North pole detecting or both South pole detecting, rather than one North pole detecting and one South pole detecting) could be disposed at the first and second positions. In any implementation, the signal for deactivating the motor  18  may be generated based on the flux strength reaching (e.g., decreasing to or increasing to) a threshold value, which may be zero or a non-zero value, and may rely on whether the flux strength has reached zero and then subsequently risen. 
     As shown in  FIG.  6   , the magnet  102  includes a notch  146  to visually assist a manufacturer that is placing the magnet  102  on the carrier  86  during the assembly or manufacturing process, such that the North pole and South pole faces  110 ,  114  can be correctly oriented with respect to the first and second sensors  122 ,  126 . By including a magnet  102  with North pole and South pole faces  110 ,  114  with a pole junction P D  therebetween, the first and second sensors  122 ,  126  both have more precise sensing windows in determining when the ball screw  38  has reached the first and second positions, respectively. Thus, the controller  134  is able to more precisely stop the ball screw  38  in the first and second positions, achieving a benefit that is normally only available with traditional limit switches, while increasing the longevity of the pulling mechanism  18 , as a magnet  102  in combination with Hall-effect sensors  122 ,  126  has greater longevity than traditional limit switches. In other implementations, the magnet  102  with North pole and South pole faces  110 ,  114  can be used in other applications and tools where precise sensing windows are necessary. 
     Although the disclosure has been described in detail with reference to certain preferred implementations, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described. Various features of the invention are set forth in the following claims.