Method for surface treatment of work pieces
0 United States Patent [1 1 1111 3,879,902  
 Haberlin 1 1 Apr. 29, 1975 [5 METHOD FOR SURFACE TREATMENT OF 2.239.073 4/1941 Aray 51/15 x WORK PIECES 3.204.782 9/1965 Kendall 51/215 CP X 3.517.465 6/1970 Freeman.... 51/9 X [75] Inventor: Hans Paul Haberlin, Schaffhausen. 1 03937 9 1971 M nn 51/15 X Switzerland 3,626.64] 12/1971 Powell 51/15 [73] Assigneel Wheelabrator Fn e, Inc New York. 3.748.787 7/1973 Carpenter 51/15 [22] Filed; Mar. 7, 1974 Primary Examiner-Donald G. Kelly Appl. No.: 449,046  
 Related U.S. Application Data [62] Division of Ser. No. 255,778. May 22. 1972. Pat. No.  
  52] U.S. Cl. 51/319 1 Int. Cl. 1324c 1/00 [581 Field of Search 51/319-321. 51/9. l4, 15, 74 R, 215 R. 215 CP, 215 H [56] References Cited UNITED STATES PATENTS 1.875.994 9/1932 Davis 51/15 1571 ABSTRACT A suspension track centrifugal blasting machine which includes a suspension yoke having rotatable legs for clamping blanks and means for rotating the legs with the blanks clamped therebetween during passage through the blasting area and for a distance beyond the blasting area to effect removal of the blank media.  
 3 Claims, 13 Drawing Figures PATENTi-immzemzs SHEET10F3 PATENTEUAmzs I975 sum 2 BF i METHOD FOR SURFACE TREATMENT OF WORK PIECES This is a division of application Ser. No. 255,778, filed May 22, 1972, now US. Pat. No. 3,813,817.  
  This invention relates to a method for the surface treatment of blanks which are suspended from movable suspension means by which they are conveyed from a loading station, through a blasting chamber, and to an unloading station.  
  Suspension track centrifugal blasing machines for the continuous or intermittent surface treatment of blanks, such as cylinder heads, cylinder blocks, gear housings and the like, are known wherein the blanks, at the loading station, are attached to or placed on suspension means having vertical axes of rotation.  
  The aforementioned suspension track centrifugal blasting machines are subject to a number of disadvantages. The blanks, placed on suspension means with vertical axes of rotation, require the use of a building of considerable height for accommodating the centrifugal blasting machines. Moreover, the utilization of the centrifugal jet blast is not optimum with multi-base suspension means. The unguided suspension means is subject to oscillating movements in the machine with corresponding undesirable effect on the control of the blasting operation. With multi-base suspension means, the proper placement of the individual blanks requires the utilization of a relatively large amount of labor with corresponding increase in labor cost. Placing the item on carrier hooks or trolleys at the loading station, and the pickup of the blanks at the unloading station, requires, especially in the case of intermittent and/or continuously operating machines, a large number of people. Blanks weighing less than 55 pounds are normally loaded and/or unloaded manually. On the other hand, heavier blanks can be moved to the suspension means only with relatively large expenditures in time and skilled personnel by means oflifting means. Cylinder heads and cylinder blocks, particularly, are suspended so that they do not rotate about their own longitudinal axes, with the result that a relatively large amount of blasting media remains entrapped in the channels of the blanks, even after removal from the machine. Removal of the blasting media, entrapped within the channels or grooves, requires special installations and considerable expenditure of time.  
  For example, continuously operating centrifugal blasting machines are known wherein tools are automatically placed into a basket mounted for rotatable movement and moved through the treatment chamber of the blasting machine. However, such means are economical only when employed with relatively large volumes of small blanks of uniform dimension or design. A particular disadvantage of such machines is that each blank requires its own specially designed basket such that large costs are incurred when operating with blanks of different sizes.  
  It is an object of this invention to provide a method for the surface treatment of blanks which avoids the above described disadvantageous characteristics of previous methods.  
  These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the following drawings in which FIG. 1 is a longitudinal view of the machine, embodying the features of this invention showing the feed conveyor, loading station, feed chamber, blasting chamber, blasting media emptying chamber, unloading station and discharge conveyor;  
  FIG. 2 is a sketch of the machine shown in FIG. 1 from the blasting chamber to the discharge conveyor;  
  FIG. 3 is a sectional view taken along the line 33 of FIG. 1;  
  FIG. 4 is a lateral view taken of the machine in the direction of arrow A in FIG. 1;  
  FIG. 5 is a suspension means for blanks rotating about the longitudinal axis through the machine with the aid of a traction chain and a drive to rotate the blanks by a dragging chain;  
  FIG. 6 is a sectional view through the machine taken along the line 66 of FIG. 5;  
  FIG. 7 is a sectional view taken along the line 7-7 of FIG. 5;  
  FIG. 8 is a view of the rubber sealing means as employed in the feed chamber, the blasting chamber, the blasting media discharge chamber and of the individual self-adjusting yoke;  
  FIG. 9 is a view of the sealing means at the ceiling of the chamber in the area of a leg provided with an entrainment means drive of a blank carrier yoke;  
  FIG. 10 illustrates a suspension means of the type shown in FIG. 5, but with self&#39;propelling motor for the translation and a drive motor for the rotation of the blank;  
  FIG. 11 is a sectional view taken along the line l1-11 of FIG. 10;  
  FIG. 12 is a partial view of the suspension means taken in the direction of the arrow B in FIG. 10; and  
  FIG. 13 is a sectional view taken along the line 13-13 of FIG. 10.  
  In accordance with the practice of this invention, use is made of a method for the surface treatment of blanks, which is characterized by the following steps:  
  a. the blanks are lifted with a lifting table to the appropriate loading height at the loading station, that is, with the horizontal axis of gravity of the blanks aligned with the axis of rotation with the entrainment means of a carrier yoke and firmly clamped horizontally between the entrainment means;  
  b. the blanks, now firmly clamped horizontally to the carrier yokes, are conveyed from the loading station consecutively through an inlet chamber, the treatment or blast chamber and a blasting media emptying chamber, and are placed in rotational movement about a horizontal axis while in the blasting chamber and in the blasting media emptying chamber whereby the blanks are subjected to a surface treatment by the centrifugal jet blast with media during passage through the blasting chamber and the blasting media remaining in the cavities of the blanks is removed by centrifugal or gravitational force in the blasting media emptying chamber;  
  c. subsequent to the centrifugal removal of the media, the rotational movement of the blank is stopped and the blank is conveyed from the blasting media emptying chamber to the unloading station until located directly above the lifting and lowering table, at which time it is separated from the carrier yoke and deposited on the lifting and lowering table for delivery to a conveyor.  
  The suspension track centrifugal blasting machine of this invention differs from the suspension track centrifugal blasting machines of the prior art in that use is made of lifting and lowering tables arranged at the outer ends of the feed conveyor, use is made of a discharge conveyor for blanks located below a guide rail, and suspension means designed in the form of blank carrier yokes, and wherein the blank carrier yokes, suspended from the trolleys, have two carrier yoke legs movable horizontally in the direction toward and away from each other for clamping the blanks therebetween, and a pneumatically or hydraulically operated unit arranged between said legs whereby entrainment means placed into rotation by a drive are located at the lower ends of both carrier yoke legs.  
  With reference now to the drawings, a suspension track centrifugal blasting machine is shown, comprising suspension means movable on a rail 36 and designed in the form of blank carrier yokes 20. The centrifugal blasting machine is provided with three chambers, namely a feed chamber 1, a blasting chamber 2, and a blast media emptying chamber 3. Both outer chambers 1 and 3 are each sealed by a ceiling area, not shown in detail, but well known to the prior art, such as curtains 4, while the blasting chamber 2, in contrast to both outer chambers l and 3, has a curtain area 4 on each end. In this connection, it should be noted that the curtain area 4 may be replaced by a sluice system with rotatable or displaceable gates.  
  FIGS. 5 to 9 show a blank carrier yoke comprising two longitudinal carriers mounted for guided movement toward and away from each other and connected at their upper ends to plates 39 and 40. Each of the plates 39 and 40 are provided with a fork 32, a pin 33 being connected in an articulated manner with said fork and engaged in the roller suspension system 34 and/or 35 so that a curved trip is possible along the guide rail 36. The roller suspension systems 34-35 are connected in a manner well known to the prior art via entrainment means 38 to a pull chain 37.  
  An additional component of the blank carrier yoke 20 is a pipe 42 rigidly connected with plates 40 and 41 and reinforced by a rib 43 with the pipe terminating into the rotary head 44. A shaft 45 is positioned for rotatable movement in the pipe 42. At the upper end, the shaft 45 is operatively connected to be propelled by a drag chain 46, chain wheel 47 and an angle drive 48 to cause rotational movement of the blanks in the treatment chamber 2 and in the blasting media emptying chamber 3 about an axis 16 of rotation.  
  A pneumatic operating member 49 is located between yoke legs 50 in order to displace the transportable yoke legs 50 which is guided in relation to the longitudinal carriers 30 via a lift bar 51 of the pneumatic operating member 49.  
  A loading station 14 is provided at the input side of the feed chamber 1 and an unloading station 17 is located at the discharge side of the blasting media emptying chamber 3. The loading station 14 and/or the unloading station 17 are each provided with a pneumatically or hydraulically operated lifting table 15 and/or 18 by which the blank 12 is displaced vertically between two yoke legs 50 of a suspension means and/or removed therefrom. A rotary head 44 is operatively connected to the lower end of one yoke leg 50, while an idling rotary head 53, with entrainment opening 54, such as an internal quadrangle, is provided at the lower end of the outer yoke leg 50, analogous to the rotary head 44. These openings 54 are used to receive entrainment discs 55 of any shape adjusted individually to the blank, such as lathe dogs, clamping discs, and the like. These entrainment discs 55 are loosely placed into the apertures 54 of the rotary heads 54 and 53.  
  FIGS. 10, 11, 12 and 13 show an additional embodiment of a blank carrying yoke 20 where, in contrast to the above described embodiment, the drive of the entrainment means 55 is not accomplished with the aid of a drag chain via a chain wheel. Instead, use is made of an individual drive and a motor gear 65. The blank carri er yoke 20, suspended from two trolleys 67 and 68, is thereby equipped with a self-propelling motor gear 66 of known design, whereby the gear 66 is assembled to a trolley 67 from which the one yoke leg 50 is suspended. Both motor gears 65 and 66 are fed by power supply rails, which are not shown in detail.  
  In accordance with FIGS. 10 and 11, a stop bar 69 is positioned to limit the stroke of the yoke leg 50, which can be inserted at the carrier 30 into perforations 70 arranged at predetermined intervals so that, depending upon the length of the blank the stroke can be modified within predetermined limits. The clamping of the blanks 12 between both of the legs 50 can be accomplished in a manner well known to the prior art, as by means of a spring, pneumatically, hydraulically, electromagneticallly, or with a spindle motor. A valve 52, operable at the loading and/or unloading station, is provided for the pneumatic operation of the yoke legs to effect their release.  
  A slot 73 covered by a rubber seal 71 is provided for sealing the ceiling 72 of the chambers 1, 2 and 3. In the embodiment represented in FIGS. 10, 11 and 13, the slot is arranged parallel to the operating rail 76. For protection of the seal 71, a shield 77 is placed at the carrier yoke 20. This protective shield is adjustable in a telescoping manner to the corresponding clamping widths at the carrier yoke.  
  The blasting machine described operated in the following manner:  
  The blanks 12 are conveyed on a feed conveyor 13 to the loading station 14. There they are lifted by the lift table 15 to the appropriate loading height, with the horizontal axis of gravity of the blanks l2 aligned with the axis of rotation 16 of the carrier yoke 20 and the blank is firmly clamped thereon. From there, the carrier yokes 20, loaded with the blanks 12, are moved consecutively through the feed chamber 1, the blasting chamber 2 and the blasting media emptying chamber 3 and through the curtains or sluice gates 4 separating the chambers. In the blasting chamber 2 and in the blasting media emptying chamber 3, the blanks 12 held by the carrier yokes 20, are caused automatically to rotate so that the blanks 12 are optimally surface treated with the blast medium thrown centrifugally from the blasting machine. In the blasting media emptying chamber 3, the continual rotational movement serves to effect the complete removal of the blasting medium remaining in the cavities of the blank, as by centrifugal and/or gravitational force. Once the blanks 12 have reached the unloading station 17, their rotational movement is automatically brought to a stop and both carrier yoke legs 50 are moved with the entrainment means 55 in the direction away from each other to release the blank which is now located directly above the lifting and lowering table 18 and deposited thereon. Subsequently, the blank 12 is lowered by the lifting and lowering table 18, to the level of the discharge conveyor 19 onto which it is placed for conveying the blanks 12, while the empty blank carrier yokes 20 are returned to the loading station 14.  
  Regarding the firm clamping of the blanks 12 at the loading station 14, as shown in FIG. 5, compressed air is released from the pneumatic operating member 49 via valve 52, and the back pressure spiral spring 56 draws the yoke leg 50 toward the blank 12 so that the latter is clamped between both entrainment means 55. In this manner it is made ready for travel through the chambers l, 2 and 3. The lifting table 15, at the loading station, then returns to the starting position and/or to the level of the feed conveyor 13.  
  For the blanks 12, other conveying operations can be utilized in accordance with the concepts of this invention. For example, some blank carrier yokes may be coupled in groups of yokes 20 with only one of them equipped with traction means, a motor gear or drag chain entrainment means. Moreover, several embodiments of the subject matter of the invention may be used to feed and remove the blanks. Also, a number of possibilities for surface treatment of the blanks are feasible, whereby the blanks 12 are conveyed, such as through two coupled or separated blasting chambers in order to expose the blanks to double treatment time or to treat the blanks with different radiation or blasting means.  
  The described suspension track centrifugal blasting machine provides a number of advantages over centrifugal blasting machines of the prior art. As a result of the complete automation of the loading and unloading operations, the labor required is noticeably reduced. The machine, which is of relatively simple design, makes it possible to increase performance and it is relatively easily adjustable to all local conditions.  
 It will be understood that changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.  
  I claim: 1. A method for the surface treatment of blanks while being carried by a mobile suspension means from a loading station through a blast chamber and blast medium removal chamber to an unloading station, comprising the steps of:  
 raising the blanks at the loading station to a height wherein the center of the blanks correspond approximately to a horizontal axis of rotation of the clamping means on the mobile suspension means,  
 clamping the raised blanks between clamping means,  
 carrying the blanks in said clamping means from the loading station through the blast chamber and the blast medium removal chamber to the unloading station,  
 rotating the blanks about said horizontal axis while being conveyed through the blast chamber and the blast medium removal chamber,  
 blasting the blanks with blasting medium thrown centrifugally by blasting wheels during passage through the blast chamber,  
 releasing the blanks and lowering the released blanks at the unloading station.  
  2. The method as claimed in claim 1 in which at least two clamping means in the form of blank carrier yokes are coupled together for movement through the blast chamber.  
  3. The method as claimed in claim 1 which includes the steps of conveying the blanks to the loading station and conveying the blanks away from the unloading station.