Patent Publication Number: US-2013238272-A1

Title: Touch trigger probe

Description:
FIELD OF THE INVENTION 
     The present invention relates to a touch sensing device, and more particularly to a touch trigger probe to support a lateral sensing operation and a longitudinal sensing operation. 
     BACKGROUND OF THE INVENTION 
     In an automated working process, a workpiece has to be positioned precisely so as to be worked by a machine tool accurately, so a position of the workpiece is measured by a position measuring equipment in advance. 
     Conventional measuring equipment for the workpiece drives a piston rod thereof to move upward and downward by air entering and discharging operation of a cylinder so as to drive an actuating member further. Since the actuating member connects with a linear slide track, when the piston rod pushes the actuating member, the linear slide track is driven to slide in a linear bearing, such that a probe below the actuating member moves upward or downward. However, such a probe is comprised of a resilient element coupled with a touch tip, and a sensing of a datum surface or a measurement of a working point for the workpiece is executed in a longitudinal contacting manner, limiting the measurement of the datum position of the workpiece and affecting the positioning accuracy. Another measuring equipment for a workpiece, such as a probe fixed on a coordinate positioning device to measure a profile of an object is disclosed in U.S. Pat. No. 7,792,654, the probe contains a touch tip, a spring box, a compression spring, an upper component, and a sensing element. The touch tip includes a pointed end to contact with an object, the upper component includes a pair of rollers, and the sensing element includes three balls in contact with the rollers. When the touch tip moves longitudinally to contact with the object via the pointed end, the compressing spring in the spring box senses the contact with the object; when the touch tip moves laterally to contact with the object through the pointed end, the upper component presses the balls by ways of the rollers, and a semiconductor strain gauge of the sensing element senses the contact with the object. Nevertheless, such a probe is complicated and is provided with excessive sensing elements to achieve a longitudinal and lateral contact sensing, causing a high production cost. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a touch trigger probe that is capable of overcoming the shortcomings of the conventional touch trigger probe. 
     To obtain the above objective, a touch trigger probe provided by the present invention is used to determine whether contacts with a workpiece and contains a sleeve, a sensing segment and a transmitting segment. The sleeve extends along an axial direction and includes an opening, a first chamber communicating with the opening, and a second chamber communicating with the first chamber. The sensing segment is movably located in the first chamber and includes a sensing end extending out of the opening and a driving end far from the sensing end. The transmitting segment is mounted in the second chamber and pushed by the driving end to move to a triggering position from an original position relative to the sleeve. The sensing segment has a swing sensing travel in which the workpiece laterally pushes the sensing end to drive the driving end to tilt so that the driven end is pushed by the driving end to move the transmitting segment to the triggering position. The sensing segment also has an elevation sensing travel in which the workpiece axially pushes the sensing end to drive the driving end to move axially so that the driven end is pushed by the driving end to move the transmitting segment to the triggering position. 
     Thereby, as the sensing segment of the touch trigger probe of the present invention has the swing sensing travel for lateral contact and the elevation contact for longitudinal contact to push the transmitting segment to the triggering position, the location of the workpiece can be measured. Hence, not only positioning precision of the workpiece can be enhanced, but also excessive sensing elements can be avoided to lower a production cost. 
     The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the assembly of a touch trigger probe according to a preferred embodiment of the present invention; 
         FIG. 2  is a cross sectional view showing the assembly of the touch trigger probe according to the preferred embodiment of the present invention; 
         FIG. 3  is a cross sectional view showing a swing sensing travel of the touch trigger probe according to the preferred embodiment of the present invention; 
         FIG. 4  is a cross sectional view showing an elevation sensing travel of the touch trigger probe according to the preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  are respectively a perspective view and a cross sectional view of a touch trigger probe according to a preferred embodiment of the present invention, and the touch trigger probe is used to determine whether contacts with a workpiece (not shown in the drawings) and comprises a sleeve  10 , a sensing segment  20 , and a transmitting segment  30 . 
     The sleeve  10  extends along an axial direction and is comprised of three components. The sleeve  10  includes an opening  11 , a first chamber  12  communicating with the opening  11 , a second chamber  13  communicating with the first chamber  12 , a first clamping portion  14  and a second clamping portion  15 . The first clamping portion  14  is secured on an inner wall of the sleeve  10  and is defined between the sleeve  10  and the sensing segment  20 . The second clamping portion  15  is located in the second chamber  13  and also secured on the inner wall of the sleeve  10  and defined between the sleeve  10  and the transmitting segment  30 . 
     The sensing segment  20  is movably located in the first chamber  12  and includes a holder  23  with a through hole  231  and a trigger member  24  inserted into the through hole  231 . The holder  23  is covered by the first clamping portion  14  and contacts with the first clamping portion  14  to form an arcuate interface  141  and rotates universally in the first chamber  12 . The trigger member  24  moves longitudinally in the through hole  231  and includes a sensing end  21  and a driving end  22 . The sensing end  21  extends out of the opening  11  and has a holding groove  242  to hold a touch probe  241  in different types according to using requirements. The driving end  22  is far from the sensing end  21  and includes an annular wall  222  axially extending therearound and a recess  221  surrounded by the annular wall  222 . The annular wall  222  further extends outside the through hole  231  to form a flange  223  extending outward radially and retaining on the holder  23 . 
     The transmitting segment  30  is mounted in the second chamber  13  and is pushed by the driving end  22  to move to a triggering position from an original position relative to the sleeve  10 . The transmitting segment  30  includes a transmitting member  32 , a transmission rod  34 , and a resilient element  33 . The transmitting member  32  is covered by the second clamping portion  15 , and the transmitting member  32  and the second clamping portion  15  are interposed by a plurality of rolling balls  151  to facilitate longitudinal movement of the transmitting member  32 . The transmitting member  32  also includes a driven end  31  protruded axially and a slot  321  far from the driven end  31 . The driven end  31  contacts with the driving end  22  and extends into the recess  221 . In this embodiment, a cross section of the driven end  31  is formed in a triangle shape but not be limited to this shape, for example, it is formed in a semi-arc shape or a trapezoid shape. The transmission rod  34  is held in the slot  321  and contacts with the transmitting member  32  and extends outside the sleeve  10  from a direction far from the transmitting member  32  to trigger an external element (not shown in the drawings) to perform sensing. The resilient element  33  is located between the transmitting member  32  and the sleeve  10  and butts against the sleeve  10  to push the transmitting member  32  to contact with the driving end  22  via the driven end  31 . In this embodiment, the resilient element  33  is a spring but not be limited to this spring. 
       FIG. 3  shows a cross sectional view of a swing sensing travel of the touch trigger probe of the present invention. When the touch trigger probe is served to perform lateral sensing for the workpiece, the sensing segment  20  has a swing sensing travel in which the workpiece is in contact with the touch probe  241  to further push the touch probe  241  laterally so that the trigger member  24  drives the holder  23  to slide against the first clamping portion  14  on the arcuate interface  141  so as to drive the driving end  22  to tilt, and then the annular wall  222  pushes the driven end  31  so that the transmitting segment  30  moves toward the triggering position. Thereafter, the transmitting segment  30  is pushed by the annular wall  222  to move longitudinally via the transmitting member  32  and drives the transmission rod  34  to trigger the external element (not shown in the drawings) to perform sensing, thereby the swing sensing travel of the touch trigger probe is completed. It is to be noted that after the swing sensing travel is completed, the workpiece moves away from the touch probe  241  without contacting, and the resilient element  33  pushes the transmitting member  32  to return so that the trigger member  24  is pushed by the transmitting member  32  to return back to its original position to have a next sensing further. 
       FIG. 4  shows a cross sectional of an elevation sensing travel of the touch trigger probe of the present invention. When the touch trigger probe is applied to perform longitudinal sensing for the workpiece, the sensing segment  20  has an elevation sensing travel in which the workpiece contacts with the touch probe  241  to further push the touch probe  241  longitudinally so that the trigger member  24  slides in the through hole  231  relative to the holder  23  so as to drive the driving end  22  to move axially, and then the annular wall  222  pushes the driven end  31  so that the transmitting segment  30  moves toward the triggering position. Thereafter, the transmitting segment  30  is pushed by the annular wall  222  to make the transmitting member  32  move longitudinally and to drive the transmission rod  34  to trigger the external element (not shown in the drawings) to perform sensing, thus the elevation sensing travel of the touch trigger probe is completed. It is to be noted that after the elevation sensing travel is completed, the workpiece moves away from the touch probe  241  without contacting, and the resilient element  33  pushes the transmitting member  32  to return so that the trigger member  24  is pushed by the transmitting member  32  to return back to the original position to have the next sensing further. 
     Thereby, as the sensing segment of the touch trigger probe of the present invention has the swing sensing travel to allow the trigger member to drive the holder to slide against the first clamping portion on the arcuate interface and has the elevation sensing travel to allow the trigger member to slide in the through hole relative to the holder, and cooperation between the driving end and the driven end, the sensing segment drives the transmitting segment to perform sensing, hence the touch trigger probe is capable of measuring a workpiece&#39;s position in a lateral contacting manner or in a longitudinal contacting manner and enhancing positioning precision of the workpiece. In addition, the touch trigger probe of the present invention is not provided with excessive sensing elements, thus lowering production cost. 
     While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.