Cam-lock slider
D United States Patent 1 1 1111 3,874,040  
 Murakami Apr. 1, 1975 1 CAM-LOCK SLIDER 2,539,520 1/1951 Mikulas 24/2o5.14 A 2,968,078 1/1961 Huelster 24/205.l4 A [75] Inventor: Shoets Mumkam&#34; Kumbe Japan 3,068,542 12/1962 Firing 24/205.14 R [73] Assignee: Yoshida Kogyo Kabushiki Kaisha,  
  Tokyo, Japan Primary Examiner.lames T. McCall Assistant ExaminerDarrell Marquette [22] 1973 Attorney, Agent, or FirmBucknam and Archer [21] Appl. No.: 406,581  
 [57] ABSTRACT [30] Foreign Application Priority Data A cam-lock type of slider is disclosed for use on a 0m. 19, 1972 Japan 47-1210141u slide fastener, which slider is Provided With an internal recess in the bottom wing for locking engagement with [52] U.S. Cl 24/205.14 R fastener nts when h latt r are f r d down by [51] Int. Cl A44b 19/30 a cam n g a t the pull ta he r ss is config- [58] Field of Search 24/205.l4 A, 205.14 R Such at hen the Slider is locked against movement on the fastener, an element on one stringer tape- [56] Referenc Cit d is held in partly or half coupled relation to the mating UNITED STATES PATENTS element on the opposite stringer tape.  
 l,998,33l 4/1935 Norton 24/205.l4 A 1 Claim, 4 Drawing Figures CAM-LOCK SLIDER BACKGROUND OF THE INVENTION This invention relates to sliders for slide fasteners and has particular reference to such a slider which has cam means to lock the same against movement on the fastener.  
  Heretofore, a number of sliders of the so-called camlock type have been proposed in the art, and such known sliders are typically constructed with a cam or cams formed integrally with the pull tab and adapted to press the fastener elements into locking engagement with an internal recess in the bottom wing of the slider. The recess extends to a full transverse width of the bottom wing or element-guide channel between the opposite side flanges of the slider, and hence accommodates the fastener elements that are positioned thereat within the guide channel in the slider. As the fastener elements are thus pressed by the cam into locking engagement with the recess substantially parallel therewith, the tape edges carrying the rows of elements are likewise pressed together with those elements and squeezed forcibly along the contour of the recess, with the resulting resistance of the thus forced tape edges rendering the slider locking operation extremely heavy and sluggish. This would further invite undue frictional wear of the cam part of the pull tab and the surfaces of the fastener elements. Furthermore, because of the necessity of providing an element-guide surface wall of the prescribed thickness at the front and back of the recess in the bottom wing, the overall length of the slider is increased thereby making its appearance less attractive. To produce sliders having such a recess has been also rendered quite difficult by die-casting or injection molding.  
 SUMMARY OF THE INVENTION Whereas, it is an object of the invention to provide improvements in such cam-lock sliders whereby the slider locking and unlocking operation is performed with a maximum of reliability and smoothness and with a minimum of resistance produced in the elementcarrying tape edges.  
  It is another object of the invention to provide an improved cam-lock slider which is relatively small in its overall length and which can be manufactured with ease by die-casting or injection molding.  
  These objects together with other features of the invention will be better understood from the following detailed description of certain preferred embodiments taken in conjunction with the accompanying drawings.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a cam-lock slider according to the invention with parts broken away to expose the interior thereof;  
  FIG. 2 is a longitudinal cross-sectional view of the slider of FIG. 1 of which top wing has been removed to better show how the fastener elements are locked in a recess in the bottom wing;  
  FIG. 3 is a transverse cross-sectional view taken along the line IIIIII of FIG. 2; and  
  FIG. 4 is a perspective view of the bottom wing of the slider having a modified recess according to the invention.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and FIG. 1 in particular, there is shown a slider 10 embodying the present invention which is generally of the common construction designed for taking two rows of discrete fastener elements&#39;into and out of engagement on the respective stringers to close and open the slide fastener. Each row of fastener elements E (FIGS. 2 and 3) is secured to a beaded inner edge or element-carrying edge I of one stringer tape T and disposed for coupling engagement as at coupling heads 2 with the corresponding row of elements on the other stringer tape T.  
  The slider 10 comprises a top wing 11 and a bottom wing 12 which are connected together at one end by a neck portion 13. Each wing has inwardly directed side flanges 14 which together with the neck 13 define a Y- shaped guide channel 15 for the passage of the rows of fastener elements E during opening or closing of the fastener. A pull tab 16 generally rectangular in shape is pivotally connected at one end by a pintle 17 to a pair of laterally spaced lugs or bails l8 projecting upwardly from the top wing 11. Intermediate the lugs 18 there is formed an opening 19 in the top wing 11 through which a downwardly projecting cam 20 integral with the pull tab 16 is admitted when the latter is swung into locking position as better shown in FIG. 1. The cam 20 is provided with a rounded corner so as to engage smoothly upon the fastener elements E.  
  According to an important aspect of the invention, there is provided a recess 21 in the bottom wing 12, which recess is defined by side shoulders 22 extending parallel with a longitudinal axis of the slider 10 and a transverse front shoulder 23 connecting the side shoulders 22 at one end adjacent to a point corresponding to the position of the cam 20 on the pull tab 16, the recess 21 being thus closed at one end by the front shoulder 23 but open at the opposite end registering with an extremity of an exit end 10&#39; of the slider 10. The side shoulders 22 are equidistant from the respective side flanges 14 as indicated by the reference character D which refers to element-guide surface bifurcations 24 extending coplanar with the inner surface 25 of the bottom wing 12. The bifurcations 24 are each wide enough to permit the sliding movement of the fastener elements E thereon during opening or closing of the fastener, without causing the fastener elements E to fall into the recess 21 except when the slider 10 is brought positively into locked position as later described.  
  It is to be noted that the locking cam 20 has an operative position such that it engages upon one element Ea in either row which is half or partly coupled with the mating element Eb in the opposite row and which is therefore inclined relative to a line of right angles to the longitudinal axis of the fastener or fastener element rows. To lock the element Ea more effectively, the front shoulder 23 is slightly tapered towards the neck 13 so as to permit the inclined element Ea to bear smoothly against and to be arrested at the shoulder 23 when the slider 10 is held in locked position.  
  With this construction, the slider 10 can be locked effectively against movement on the fastener, when desired, by swinging the pull tab 16 counter-clockwise as viewed in FIG. 1 about the pintle 17 into the locking position wherein the pull tab 16 lies flat against the slider top wing 11, with the locking cam 20 pressing the element Ea partly coupled with the corresponding element Eb into locking engagement with the recess 21. More specifically, the element Ea has its coupling head portion e, pressed against the bottom of the recess 21 with the leg portions 2 positioned at one of the bifurcations 24, so that the tape T is slightly bent inwardly along the element-carrying edge I as shown in FlG. 3. Advantageously, since the element Ea is thus disposed to engage only at its coupling head portion e, with the recess 21 while the element Ea is held in partly or half coupled relation to the corresponding element Eb, and the tape portions that lie between the side flanges 14,14 are held substantially free from any stresses with the tape edge I alone directed slightly downwardly with respect to the plane of the fastener, the slider can be locked and unlocked by a light finger touch with a minimum of resistance, and hence frictional wear of either the cam or the element Ea can be held to an absolute minimum. Also advantageously by virtue of the configuration of the recess 21 that has been described, the absence of the element-guide surface of the bottom wing 12 at the back of the recess 21 makes it possible to so much reduce the overall length of the slider 10 and render the same relatively compact. Further advantageously, the provision of bifurcations 24,24 ensures that the rows of fastener elements E be guided in horizontal alignment therealong without being caught in the recess 21, thereby facilitating the movement of the slider 10.  
  It will be further appreciated that the slider 10 having such characteristic recess 21 can be made with ease by die-casting or injection molding.  
  Reference to FIG. 4 shows a modified recess 26 according to the invention which has a bottom surface bisected longitudinally into identical halves 27,27 which are inclined downwardly and inwardly towards each other and merged at a longitudinal center 28.  
 The recess 26 in this embodiment is closed at one end adjacent the neck 13 by a transverse front shoulder or abutment 29, similar to the front shoulder 23 previously described, but open at the other or opposite end registering with the extremity of the exit end 10&#39; of the slider 10. The advantage of the modified recess 26 is that the fastener elements E when pressed by the locking cam 20 are tilted easily along the inclined bisected bottom surface 27 (27&#39;) thereby facilitating the locking operation with increased smoothness.  
 What is claimed is:  
  1. In a cam-lock slider for a slide fastener wherein the slider has a top wing, a bottom wing, a neck portion interposed between and connecting the top and bottom wings at one end thereof, said wings each having a pair of angularly turned flanges on each side thereof which together with said neck portion define a Y-shaped guide channel within the slider to provide the passage of two rows of fastener elements each having a coupling head portion, a pull tab pivotally connected to said top wing, and a cam projecting from and integral with said pull tab, the improvement which comprises said bottom wing being provided with a shallow recess therein longitudinally extending from a point adjacent said neck portion to the free end of the slider opposite said end at which the top and bottom wings are connected together, said recess extending transversely between bifurcated surfaces elevated with respect thereto each being provided between the recess and one of the side flanges and the other respectively for guiding the fastener elements slidably thereon, and said cam being adapted to take an operative position in which it depresses only the coupling portion of one of the fastener elements in one of the two rows into locking engagement with said recess whereby said one of the fastener elements is held in partly or half coupled relation to a mating element in the opposite row.