Abstract:
A linear guide system which is used for highly precise control of a linear position applicable in display devices, semiconductors, robots, machine tools, and the entire measurement and precision instruments industry, and more specifically, an adjustable preload type linear guide system, wherein a base member and a slide member are slidably connected with each other for linear motion, and a linear motion actuator, such as a ball screw, a hydraulic cylinder, and a linear motor, is disposed between the base member and the slide member, thereby enabling the slide member to move linearly relative to the base member.

Description:
TECHNICAL FIELD 
     The present invention relates to a linear guide system which is used for highly precise control of a linear position applicable in display devices, semiconductors, robots, machine tools, and the entire measurement and precision instruments industry, and more particularly, to an adjustable preload type linear guide system, wherein a base member and a slide member are slidably connected with each other for linear motion, and a linear motion actuator, such as a ball screw, a hydraulic cylinder, and a linear motor, is disposed between the base member and the slide member, thereby enabling the slide member to move linearly relative to the base member. 
     BACKGROUND ART 
     Linear motion actuators are generally used for highly precise control of a linear position applicable in display devices, semiconductors, robots, machine tools, and the entire precision instruments industry, and a linear motion mechanism including a linear motion guide, for example, may be used as a linear guide unit that guides linear position control of the linear motion actuator. 
     When linear motion mechanism systems are configured using the linear motion mechanism, as the weight of the linear motion guide and the weight of a support plate increase, cost for manufacturing the linear motion mechanism system increases, and the speed of the linear motion mechanism system is limited due to an increase in the size (volume) of the linear motion mechanism system. 
     Such linear motion mechanism systems using the linear motion mechanism are designed and manufactured according to their applied fields and thus are not compatible with other systems, and manufacturing cost thereof increases. 
     In addition, since the weight of the linear motion mechanism systems is heavy, there is a limitation in applying the linear motion mechanism systems to equipment, and their usage is restrictive. 
     In these days, linear guide units are disclosed as linear motion mechanisms with better efficiency, the linear guide units including a base member having a function of a prop, a slide member that is slidably installed at the base member, and an actuator that moves the slide member relative to the base member. 
     A guide portion for guiding slide motion is disposed on both the base member and the slide member, and a linear motion block is installed at the guide portion. The linear motion block includes a ball bearing including a plurality of steel balls that are moved on a caterpillar and embedded in the ball bearing so as to smoothly guide linear motion by minimizing friction that may occur when guiding slide motion. 
     Such general linear guide units have the following problems. 
     First, a preload applied to a ball bearing installed at the guide portion disposed on the base member and the slide member cannot be adjusted. That is, the steel balls of the ball bearing are combined with the ball bearing in such a way that the steel balls having the sizes selected according to levels of preloads when the steel balls are initially combined with the ball bearing are inserted in the ball bearing, and the preload of the ball bearing is varied as the ball bearing is worn out when it is being used, and thus the preload of the ball bearing cannot be adjusted. Since, in this way, the preload of the ball bearing cannot be adjusted when the ball bearing is being used, the degree of operation precision that may be lowered when the ball bearing is being used cannot be corrected. Thus, vibration and noise occur, and the life span of the linear guide units is reduced. 
     Second, the base member and the slide member are formed of heavy metals with high rigidity and high abrasion resistance so as to ensure abrasion resistance so that the range of application of the linear guide units is limited. 
     Third, steel balls having the same diameter are used in the ball bearing, as illustrated in  FIG. 14 . Friction between the steel balls occurs when the ball bearing is activated, resulting in accelerating abrasion and occurring noise and vibration. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     The present invention provides an adjustable preload type linear guide system that may adjust a preload applied to a ball bearing so that abrasion of the ball bearing is reduced, occurrence of noise and vibration is prevented and highly precise linear motion is guided. 
     The present invention also provides an adjustable preload type linear guide system, of which a life span is remarkably increased by preventing abrasion of a ball bearing. 
     Technical Solution 
     According to an aspect of the present invention, an adjustable preload type linear guide system includes: a base member having a base body, and a pair of base rails which are disposed in parallel to each other on the base body; a slide member having a slide body, and a pair of slide rails which are disposed on the slide body to face the pair of base rails, wherein the slide rails slide relative to the base rails by a ball bearing which is installed between the base rails and the slide rails, thereby enabling the slide member to slide relative to the base member; and a preload adjustment unit which is installed between one of the slide rails and the slide body for adjusting the intervals and angles of the slide rails with respect to the slide body, thereby adjusting the preload of the ball bearing which is disposed between the base rails and the slide rails. 
     Advantageous Effects 
     In an adjustable preload type linear guide system according to the present invention, a preload of a ball bearing may be adjusted when the ball bearing is being used so that unnecessary abrasion of the ball bearing may be prevented. 
     In addition, occurrence of noise and vibration that may occur due to an improper preload of the ball bearing may be prevented so that the adjustable preload type linear guide system that guides linear motion with high precision may be provided. 
     By preventing unnecessary abrasion of the ball bearing, the present invention provides an adjustable preload type linear guide system, of which a life span is remarkably lengthened. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an adjustable preload type linear guide system according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the adjustable preload type linear guide system illustrated in  FIG. 1 ; 
         FIG. 3  is a side cross-sectional view of the adjustable preload type linear guide system illustrated in  FIG. 1 ; 
         FIG. 4  is an enlarged view of a portion of  FIG. 3 ; 
         FIG. 5  is an enlarged view of another portion of  FIG. 3 ; 
         FIG. 6  is an enlarged view of a portion of  FIG. 5 ; 
         FIG. 7  illustrates a structure of a ball bearing illustrated in  FIG. 7 ; 
         FIG. 8  is an exploded perspective view of a preload adjustment unit illustrated in  FIG. 1 ; 
         FIG. 9  is a planer cross-sectional view of the adjustable preload type linear guide system illustrated in  FIG. 1 ; 
         FIG. 10  is a cross-sectional view of the preload adjustment unit illustrated in  FIG. 8 ; 
         FIGS. 11 and 12  are enlarged views of portions of  FIG. 10 ; 
         FIG. 13  is an enlarged view of a portion of  FIG. 2 ; and 
         FIG. 14  illustrates a structure of a general ball bearing. 
     
    
    
     BEST MODE 
     The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.  FIG. 1  is a perspective view of an adjustable preload type linear guide system 
     According to an embodiment of the present invention, and  FIG. 2  is an exploded perspective view of the adjustable preload type linear guide system illustrated in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the adjustable preload type linear guide system according to the current embodiment includes a base member  100 , a slide member  200 , and a preload adjustment unit  600 . 
     Referring to  FIGS. 3 and 4 , the base member  100  includes a base body  101  and a pair of base rails  151  and  152  which are disposed on the base body  101 . The base body  101  is formed of a light-weight aluminum profile that is formed by extrusion molding an aluminum material. Rail combination grooves  111  and  121  are formed in both sides of the base body  101  in a lengthwise direction of the base body  101 , and the base rails  151  and  152  are inserted in the rail combination grooves  111  and  121  and thus are combined therewith. The base rails  151  and  152  are formed of an abrasion resistance material with higher rigidity than aluminum and are manufactured by cold rolling or drawing. 
     Referring to  FIGS. 5 and 6 , after a metal adhesive is filled in the rail combination grooves  111  and  121  of the base body  101 , the base rails  151  and  152  are inserted in the rail combination grooves  111  and  121  and thus are combined therewith. 
     Referring to  FIGS. 3 and 4 , the slide member  200  includes a slide body  201  and a pair of slide rails  251  and  252  which are disposed on the slide body  201 . The slide body  201  is formed of a light-weight aluminum profile that is formed by extrusion molding an aluminum material. Rail combination grooves  211  and  221  are formed in both sides of the slide body  201  in a lengthwise direction of the slide body  201 , and the slide rails  251  and  252  are inserted in the rail combination grooves  211  and  221  and thus are combined therewith. The slide rails  251  and  252  are formed of an abrasion resistance material with higher rigidity than aluminum and are manufactured by cold rolling or drawing. 
     Referring to  FIGS. 5 and 6 , after a metal adhesive is filled in the rail combination grooves  211  and  221  of the slide body  201 , the slide rails  251  and  252  are inserted in the rail combination grooves  211  and  221  and thus are combined therewith. 
     The slide member  200  having the above structure is disposed between linear motion guide portions  110  and  120  of the base body  100 . In this case, the pair of base rails  151  and  152  of the base member  100  and the pair of slide rails  251  and  252  of the slide member  200  are disposed to face each other. In this case, a ball bearing  300  including a plurality of balls is disposed between the base rails  151  and  152  and the slide rails  251  and  252  so that the slide rails  251  and  252  are smoothly slid relative to the base rails  151  and  152 . 
     Referring to  FIG. 3 , an actuator accommodation space in which an actuator is to be disposed is formed in a middle portion of the adjustable preload type linear guide system in which the base body  101  of the base member  100  and the slide body  201  of the slide member  200  face each other. 
     Various types of devices, such as a linear motor, a ball screw, an air cylinder, a timing belt/pulley mechanism, and the like, may be used as the actuator. Since a proper actuator has only to be installed in the actuator accommodation space according to a usage purpose in this manner, the present invention has high compatibility. 
     Referring to  FIGS. 2 through 4 , two tracks  410  are formed on the slide body  201  to pass through the slide body  201  in a lengthwise direction of the slide body  201 . Insertion grooves  153  and  253  that are formed in the base rails  151  and  152  and the slide rails  251  and  252  are connected to the tracks  410  and constitute a caterpillar that is a path of the ball bearing  300  including a plurality of balls. 
     As illustrated in  FIG. 2 , ball guide covers  400  are respectively combined with both ends of the slide body  201  in the lengthwise direction of the slide body  201 . Two tracks  420  are formed on each of the ball guide covers  400  to connect the insertion grooves  153  and  253  and the tracks  410 , thereby preventing escape of the ball bearing  300  and connecting caterpillar travel. Dust covers  500  are combined with outsides of the ball guide covers  400 . 
     In this case, as illustrated in  FIG. 3 , a height of a central point of each track  410  of the slide member  200  is different from a height of a central point of each of the insertion grooves  153  and  253  that are formed in the base rails  151  and  152  and the slide rails  251  and  252 , and each track  420  of the ball guide cover  400  that connects the insertion grooves  153  and  253  and the track  410 , is inclined with respect to a bottom surface of the ball guide cover  400 . When the track  420  of the ball guide cover  400  is inclined with respect to the bottom surface of the ball guide cover  400  in such a way that the height of each of the insertion grooves  153  and  253  and the height of the track  410  of the sliding member  200  are different from each other, a wide actuator accommodation space may be obtained, and a radius of gyration of the track  420  of the ball guide cover  400  may be increased. That is, the radius of gyration of the track  420  of the ball guide cover  400  may be increased so that a rolling motion of the ball bearing may be smoothly performed, and the size of the adjustable preload type linear guide system may be reduced. 
     The plurality of balls of the ball bearing  300  include steel balls  310  that make a rolling motion by contacting directly the insertion grooves  153  and  253  of the base rails  151  and  152  and the slide rails  251  and  252 , and resin balls  320  that have a smaller diameter than a diameter of the steel balls  310  and are formed of a synthetic resin material to have lubrication characteristics. As illustrated in  FIG. 7 , the steel balls  310  and the resin balls  320  are alternately disposed. The resin balls  320  are rotated in an opposite direction to a rotation direction of the steel balls  310  and minimize friction resistance that may be generated between the steel balls  310 , thereby preventing occurrence of noise and vibration and providing smooth rolling motion. That is, the steel balls  310  contact directly the insertion grooves  153  and  253  and are loaded by the insertion grooves  153  and  253 , and the resin balls  320  have a smaller diameter than the diameter of the steel balls  310  and thus are not loaded by the insertion grooves  153  and  253 , thereby alleviating friction between the steel balls  310 . 
     The preload adjustment unit  600  is installed between one  251  of the slide rails  251  and  252  and the slide body  202  and adjusts an interval and an angle of the slide rail  251  with respect to the slide body  202 . In this way, the preload adjustment unit  600  adjusts a preload applied to the ball bearing  300  that is disposed between the base rails  151  and  152  and the slide rails  251  and  252 . 
     Referring to  FIGS. 8 through 12 , the preload adjustment unit  600  includes conical wedges  620  and  621  and adjustment screws  640  and  641 . 
     A stepped assembly hole  213  is formed in a boundary surface between the rail combination groove  211  formed in a linear motion guide portion  210  of the slide body  202  and the slide rail  251  on which the rail combination groove  211  and the slide rail  251  face each other. The stepped assembly hole  213  passes through the boundary surface in a lengthwise direction of the preload adjustment unit  600 . Guide support facets  212  each having an inclined surface with an inner diameter increasing from the stepped assembly hole  213  to both ends of the stepped assembly hole  213  in the lengthwise direction of the preload adjustment unit  600  are formed at both sides of the rail combination groove  221 . Inclination guide facets  255  each having the same inclination angle as that of the guide support facets  212  are formed on the slide rail  251  that faces the guide support facets  212 . 
     Springs  610  and  611  are inserted in both ends of the stepped assembly hole  213 , and the conical wedges  620  and  621  are inserted in outer portions of the springs  610  and  611 . The conical wedges  620  and  621  are tapered and are disposed between the guide support facets  212  and the inclination guide facets  255  in the lengthwise direction of the preload adjustment unit  600 . Support inserts  630  and  631  are inserted in outer portions of the conical wedges  620  and  621 , and a fixing pin  635  that prevents rotation of the support inserts  630  and  631  is combined with the support inserts  630  and  631 . The adjustment screws  640  and  641  are screw coupled to a screw hole  450  that is formed in the ball guide cover  400  and pass through the support inserts  630  and  631 , thereby adjusting advancement/retreat movement of the conical wedge  620 . 
     When the preload adjustment unit  600  allows the conical wedge  620  to move forward due to screw rotation of the adjustment screw  640 , as illustrated in  FIG. 12 , the conical wedge  620  pressurizes the inclination guide facet  255  and moves forward towards the inclination guide facet  255  of the slide rail  251  and thus pushes the slide rail  215  to the outside. 
     As a result, intervals between the base rails  151  and  152  and the slide rails  251  and  252  are decreased so that a preload applied to the steel balls  310  of the ball bearing  300  may be easily adjusted. In the same way, angles of the slide rails  251  and  252  with respect to the base rails  151  and  152  may be adjusted. 
     A preload amount indication gradation  645  is marked on a front side of the adjustment screw  640  to check and adjust the amount of preload by using screw rotation of the adjustment screw  640 . 
     The base rails  151  and  152  of the base member  100  and the slide rail  252  of the slide member  200  are securely combined with each other by performing a curling is process when a metal adhesive is filled in each of the rail combination grooves  111  and  121  and  211  and  221  and the base rails  151  and  152  of the base member  100  and the slide rail  252  of the slide member  200  are adhered to each other. 
     In this case, it is obvious that the slide rail  251  which is combined with the rail combination groove  211  of the slide member  200  and of which movement is adjusted by the preload adjustment unit  600  does not include an adhesion combination structure constituted by using a metal adhesive. 
     In addition, the insertion grooves  153  and  253  that are formed in each of the base rails  151  and  152  and the slide rails  251  and  252 , are configured in such a way that protruding friction support portions  154  and  254  are formed in the insertion grooves  153  and  253  and processed support facets  155  and  255  corresponding to curved surfaces of the steel balls  310  of the ball bearing  300  are formed on the protruding friction support portions  154  and  254  along the lengthwise direction of the preload adjustment unit  600  so that a friction force between the steel balls  310  may be minimized. 
     In addition, a stopper unit  700  that limits a linear motion distance when the slide member  200  moves linearly may be disposed on both ends of the base member  100  in the lengthwise direction of the base member  100 . 
     The stopper unit  700  includes a support plate  710  that is bolt coupled on front and rear ends of a middle portion of the base member  100 , and a shock absorber  720  and a stopper bolt  730  that are screw coupled to the support plate  710 . 
     The stopper unit  700  is stopped by a damper that is combined with a front end of the stopper bolt  730  when the slide member  200  is shock-absorbed by the shock absorber  720 . The linear motion distance of the slide member  200  is limited according to forward and backward movement of the stopper bolt  730 . 
     Referring to  FIG. 13 , an axial hole in which a ball screw is to be fixed may be formed in the support plate  710  and may be used to fix the ball screw. 
     Referring to  FIG. 3 , a coupling  800  is disposed in a central combination hole  250  of the slide member  200  so as to conveniently combine a linear motion actuator. 
     The coupling  800  includes a base  810  that is combined with the central combination hole  250 , a ball nut  820  that is rotatably combined with the base  810 , and a clamping bolt  830  that is screw coupled to the ball nut  820  and then is screw coupled to the actuator. 
     Since the ball nut  820  is combined with the base  810  to be rotated around the base  810 , even when a linear motion trajectory of the actuator and a linear motion trajectory of the slide member  200  do not coincide with each other slightly, twist of the actuator may be corrected when the ball nut  820  is rotated around the base  810 . 
     Reference numeral B/T represents a bolt for engagement and assembling of individual elements, and reference numeral  460  represents a support cover that is screw coupled to the ball guide cover  400  and prevents escape of the balls of the ball bearing  300 . 
     Hereinafter, an operation of the adjustable preload type linear guide system having the above structure will be described. 
     First, in the adjustable preload type linear guide system illustrated in  FIG. 1 , the base body  101  excluding the base rails  151  and  152  and the slide body  201  excluding the slide rails  251  and  252  are formed of aluminum materials so that the light-weight of the adjustable preload type linear guide system may be maximized. Thus, linear motion of the adjustable preload type linear guide system illustrated in  FIG. 1  is performed at high speed so that productivity of the adjustable preload type linear guide system may be improved. 
     In addition, the track  420  of the ball guide cover  400  is inclined, as illustrated in  FIG. 3 , so that a wide actuator accommodation space may be obtained. As a result, the size of the adjustable preload type linear guide system is reduced, and the adjustable preload type linear guide system is made slim so that a weight thereof may be reduced and production cost thereof may be reduced. 
     In addition, since a variety of types of actuators are disposed in the actuator accommodation space between the slide member  200  and the base member  100 , the actuator may be commonly used according to various usages and user&#39;s purposes. Since compatibility with other actuators is obtained, an exclusive linear guide system that is suitable for each equipment does not need to be designed and manufactured every time but a linear guide system is commonly designed and manufactured so that manufacturing cost of the linear guide system may be remarkably reduced. 
     In addition, the ball bearing  300  includes a plurality of steel balls  310  and a plurality of resin balls  320  so that occurrence of noise and vibration may be reduced and smooth linear motion of the slide member  200  with respect to the base ember  100  may be performed. 
     Furthermore, the plurality of steel balls  310  of the ball bearing  300  are supported by the processed support facets  155  and  255  that protrude from the insertion grooves  153  and  253  along a lengthwise direction of the preload adjustment unit  600  so that a friction force between the steel balls  310  of the ball bearing  300  may be minimized and slide motion of the slide member  200  may be more smoothly performed. 
     In the adjustable preload type linear guide system illustrated in  FIG. 1 , although the ball bearing  300  is worn out when it is being used, a preload of the ball bearing  300  is adjusted by the preload adjustment unit  600  so that the life span of the adjustable preload type linear guide system of  FIG. 1  may be lengthened. Thus, an operation of replacing the steel balls  310  of the ball bearing  300  that is worn out during its usage, like in a general linear guide system, does not need to be performed. 
     Adjusting of the preload of the ball bearing  300  causes adjustment of a rolling motion force in which the slide member  200  is moved relative to the base member  100  so that linear motion of the slide member  200  may be precisely controlled.