JP2007223741A - Work conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a constitution of a returning passage from a lead-out stage of a truck to a lead-in stage simple and compact in a conveying device for a work using the truck traveling along a conveying route. <P>SOLUTION: In such a state that the works are set in the two trucks 30, after they are tracted by a slat conveyor 10 and the work 1 is taken out at a conveying terminal end position of a work line, in order to return the truck 30 transferred to the lead-out stage to the lead-in stage, an underground pit 40 provided with the returning passage 41 is formed at a position just below the work line and a support base placed with the truck 30 is arranged at a position of the lead-out stage. The support base is attached to a rotation table reciprocally rotated by 90°, and the rotation table is lifted/operated between a raised position of the height approximately coincident with the height of a floor surface 2a of a working area of the support base placed with the truck 30 and a height position forming the returning passage of the truck 30 by a lifter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a work transfer device installed in a production line for transferring a work composed of a large-sized machine or the like and performing necessary operations such as assembly of parts to the work.

  In a production line for assembling a work composed of various vehicles or the like, parts are assembled to the work and other work is performed while the work is transported. For this purpose, the work area is equipped with a workpiece transfer device provided with transfer means. Here, a conveyor of belt type, chain type, roller type or the like is used as the conveying means. Among various conveyors, a slat conveyor formed by arranging plate-like slat plates side by side without any gap is used as a conveying means, and a carriage for mounting a work is mounted on the slat conveyor so that the carriage is connected to the carriage. The method of transporting the workpiece along the transport path is that the transport surface can be made substantially the same position as the floor surface of the work area, and the work can be placed higher than the floor surface by a carriage, etc. Since there is an advantage that workability is good when performing such operations, it has been widely used.

  In large-scale production lines that use heavy objects as workpieces, handling means such as cranes and hangers are installed at the transfer start and transfer end positions in the transfer path, and the workpieces are carried into the transfer path by these handling means. Or unloaded from the transport path. As described above, since the workpiece is installed and transported on the carriage, after the carriage reaches the unloading stage and the workpiece is taken out, the carriage must be returned from the conveyance end position to the conveyance start end position.

Since the slat conveyor is wound between a pair of sprockets on the drive side and the driven side, it is endless. It can be returned to the stage. For example, in Patent Document 1, one work is conveyed by two carts connected by a connecting rod, and the connected cart is conveyed by a slat conveyor by adsorbing the connected cart with a magnet. The structure is such that the carriage after the work is transferred at the work carry-out stage is inverted while being attracted by the magnet, and is transferred to the carry-in stage with the top and bottom reversed. It is disclosed.
JP 2002-37437 A

  By the way, in the structure of patent document 1 mentioned above, in order to invert a cart | wheel smoothly and smoothly, it is necessary to enlarge the rotation radius at the time of inversion, and each of the drive side and the driven side around which the slat conveyor is wound Sprockets with large diameter must be used. For this reason, a slat conveyor will be enlarged and a large installation space is required. As described above, from the viewpoint of workability such as assembly of parts, if the conveying surface of the slat conveyor is to be arranged at the same height as the floor surface of the work area, the return path of the slat conveyor is arranged underground. For this reason, the underground pits constituting the return path of the carriage engaged with the slat conveyor are required to be deep and wide, and the entire facility including the transfer device becomes very large.

  The present invention has been made in view of the above points, and an object of the present invention is to return a carriage from a carry-out stage to a carry-in stage in a workpiece transfer apparatus using a carriage moving along a transfer path. The configuration of the road is to be simple and compact.

  In order to achieve the above-described object, the present invention performs necessary work on a workpiece while conveying the workpiece along the conveyance route, and a plurality of carriages are provided along the conveyance route. Are arranged, and the work is placed on these carts and pulled by the transport means, and each cart has a dimension in the left-right direction larger than the dimension in the front-rear direction in the traveling direction on the transport path. The transport path is provided with a carry-in stage for carrying the cart to a transport start end position and a carry-out stage for unloading from the transport end position, and the cart is placed at the lower position of the transport path with the carry stage. A return path is provided for returning to the carry-in stage, and each of the carry-in stage and the carry-out stage has one carriage connected to the transfer path and a connection position to the return path. The lifter is lifting during provided, the lifter, the carriage is installed, it is an its features that it has a structure comprising a turntable which rotates 90 degrees horizontally.

  It is desirable to use a conveyor having a belt, a chain, a roller, etc. as a conveying means for pulling the carriage in the conveying path from the viewpoint of simplification of the structure. In order to eliminate gaps and the like, it is most preferable that the carriage is pulled by a slat conveyor. The trolley must hold the workpiece stably. If the workpiece is large, a larger carriage is required. However, since multiple trolleys are used to transport a single workpiece, the workpiece can be transported stably even if the longitudinal dimension of the traveling direction in the conveyance path of the trolley is shorter than the lateral dimension. can do. In addition, when the work is not only large but also heavy, the carriage is provided with wheels in order to minimize the load on the carriage and the work acting on the slat conveyor in the transport path. However, a rail on which the wheels roll can be provided in the transport path. Thereby, it protects so that a big load may not act on the slat board which comprises a slat conveyor.

  If the workpiece conveyance surface on the conveyance route is provided at a position substantially the same as the floor surface of the work area, the return path provided at the lower position is configured as an underground pit. As described above, the width of the return path can be narrowed by making the front-rear dimension in the traveling direction of the transport path in the carriage shorter than the left-right dimension and laterally when the carriage returns. The carriage is rotated 90 degrees in the horizontal direction by a rotary table provided on the lifter, and the rotating operation of the carriage is performed while the lifting operation is performed by the lifter, or before or after the lifting operation is started. In this way, since the carriage is separated before the conveyor is reversed, the diameter of the sprocket around which the conveyor is wound can be shortened, and as a result, the depth of the underground pit can be reduced. When rails are provided in the transport path and the load of the carriage and workpiece is received by this rail, these rails will be placed on the underlying structure, but the left and right side walls that make up the underground pit It is also possible to adopt a structure in which a structure is provided or a support is separately provided.

  As described above, the configuration of the return path from the carry-out stage of the carriage to the carry-in stage can be made simple and compact, and is formed when the work transfer surface is substantially coincident with the floor surface of the work area. The width and depth of the underground pit can be minimized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, in FIG.1 and FIG.2, let the workpiece | work 1 conveyed by a workpiece conveyance apparatus be the upper structure of a large sized construction machine. Needless to say, the workpiece is not limited to this.

  The workpiece transfer device is a workpiece 1 and is installed in a work area 2 constituting an assembly line of the workpiece 1. In FIG. 1, 3 is a carry-in stage, 4 is a work line, and 5 is a carry-out stage. The transfer device for the workpiece 1 includes a slat conveyor 10 and rails 20 that function as transfer means and constitute a transfer means, and a plurality of carriages 30, and each carriage 30 is disposed on the work line 4. A carry-in stage 3 is connected to the transfer start end position of the slat conveyor 10 in the work line 4. One carriage 30 can stand by in the carry-in stage 3, and the carriage 30 is sent from the carry-in stage 3 to the work line 4 at a predetermined timing.

  In the present embodiment, in order to transport one workpiece 1, the workpiece 1 is loaded onto two carriages 30 and is transported in the direction of arrow S by the slat conveyor 10. An unloading stage 5 is connected to the transfer end position of the work line 4. Accordingly, the work 1 is set on the carriage 30 at the conveyance start end position, and a predetermined work such as assembly of parts is performed while proceeding along the work line 4, and when the work reaches the conveyance end position and the work is finished, the work 1 Is taken out from the work line 4 and the carriage 30 is fed into the carry-out stage 5. Then, the carriage 30 carried out to the carry-out stage 5 is returned to the carry-in stage 3.

  As shown in FIG. 3, the slat conveyor 10 has a large number of slat plates 11 arranged endlessly with almost no gap. The slat plate 11 is made of a metal thin plate, FRP (Fiber Reinforced Plastics), or other resin plates. As shown in FIG. 4, they are sequentially connected by a chain 12. The slat plate 11 formed in this way is provided with a chain 12 wound around a sprocket 13, and the slat conveyor 10 is driven by rotating the sprocket 13. A pair of left and right slat conveyors 10 are arranged along the conveyance path of the workpiece 1. The transport surface of the slat conveyor 10 is substantially flush with the floor surface 2a of the work area 2. As a result, the work area 2 as a whole constitutes a substantially flat plane having no irregularities, steps, gaps and the like. Further, two rails 20 are arranged at an inner position between the left and right slat conveyors 10 to support the load of the workpiece 1.

  As described above, since the conveyance surface of the workpiece 1 in the slat conveyor 10 is substantially coincident with the floor surface 2a of the work area 2, the sprocket 13 and the like are disposed at a lower position than the floor surface 2a. Therefore, as is apparent from FIG. 4, an underground pit 40, which will be described later, is formed at a lower position of the work line 4 formed by the transport path in the slat conveyor 10, and the sprocket 13 and the like are provided in the underground pit 40. It has been. And in the floor surface 2a of the work area 2, the floor board 14 is laid in parts other than the arrangement position of the slat conveyor 10. FIG.

  As shown in FIGS. 5 and 6, the carriage 30 has a base plate 31, and a plurality of (two in the present embodiment) pillars 32 are erected on the base plate 31. A workpiece placement portion 33 is fixedly provided on the upper surface of the column 32. On the other hand, the base plate 31 is provided with four wheels 34 at the front and rear and the left and right, and two of these wheels 34 are respectively installed on the rolling surface 20a of the rail 20 provided. It rolls on the rolling surface 20a.

  The base plate 31 of the carriage 30 has a dimension that covers the upper part of the slat conveyor 10 up to an intermediate position when the wheels 34 of the carriage 30 are installed on the two rails 20. Pin insertion holes 35 are provided on the left and right sides of the base plate 31. Further, each slat plate 11 constituting the slat conveyor 10 is provided with an engagement hole 15 at a substantially central position in the traveling direction. The connection pin 36 is inserted from the upper side of each pin insertion hole 35 provided in the base plate 31 of the carriage 30, and the connection pin 36 can be engaged in the engagement hole 15 provided in the slat plate 11. It has become. Thus, the carriage 30 is pulled by the slat conveyor 10 and can move along the conveyance path.

  As is apparent from FIG. 3, the engagement holes 15 are formed in each slat plate 11, and the connection pins 36 attached to the carriage 30 are inserted into the engagement holes 15 formed in any of the slat plates 11. It can be done. As a result, the carriage 30 can be pulled at a substantially arbitrary position with respect to the slat conveyor 10. However, the engagement holes 15 are not necessarily formed in each slat plate 11, and may be formed intermittently, for example, every other piece. As is clear from FIG. 5, the base plate 31 is provided with a pin holding hole 37 that holds the connecting pin 36 so as not to protrude from the lower surface of the base plate 31 at a position adjacent to the pin insertion hole 35. . Therefore, when the carriage 30 is in a free state, the connecting pin 36 is inserted into the pin holding hole 37 of the base plate 31. When the connecting pin 36 is inserted into the pin insertion hole 35, the connecting pin 36 protrudes downward from the lower end portion of the base plate 31 and is inserted into the engaging hole 15 provided in the slat plate 11 in the slat conveyor 10. become.

  A finger ring 36 a is provided at the upper end of the connecting pin 36 so that the operator can insert and remove the pin through the pin insertion hole 35. The finger ring 36 a is larger than the hole diameter of the pin insertion hole 35. It has dimensions. Thus, when the connecting pin 36 is inserted into the pin insertion hole 35, the finger ring 36a serves as a stopper, and the connecting pin 36 is held in a suspended state. Furthermore, a sleeve 15a having a predetermined length is attached to the engagement hole 15 provided in the slat plate 11 toward the back surface thereof, that is, the surface opposite to the transport surface. Accordingly, the connecting pin 36 has a length from the engagement hole 15 to the sleeve 15a when inserted into the pin insertion hole 35.

  Here, the workpiece 1 is a large and heavy object such as an upper structure of a construction machine, and one workpiece 1 is composed of a plurality of carriages 30, in this embodiment, two carriages 30. It is configured to support. In order to stably support the workpiece 1, the workpiece mounting portion 33 in the carriage 30 has a dimension that covers almost the entire length of the workpiece 1 in the width direction (direction perpendicular to the conveying direction). Moreover, since the workpiece | work 1 is supported by two places front and back, even if it makes the workpiece | work mounting part 33 thin, the stability of the workpiece | work 1 is not impaired. Therefore, as shown in FIG. 6, when the width dimension when the carriage 30 is directed in the conveying direction by the slat conveyor 10 is A and the dimension perpendicular to the dimension is B, the dimension B is the dimension. It is smaller than A. In particular, in order to minimize the width dimension of the return path 41 when the carriage 30 to be described later returns, the dimension B is minimized on condition that the stability of the workpiece 1 is ensured.

  In the work area 2, operations such as assembling various parts to be mounted on the work 1, attaching doors, building covers, and the like are performed. For this reason, the slat conveyor 10 equipped in the work line 4 is driven at an extremely small speed. From the carry-in stage 3, first, one carriage 30 is sent to the work line 4. The carriage 30 is fed into the work line 4 manually or by pushing means such as a cylinder, and the wheel 34 is positioned on the rail 20, but the carriage 30 does not move in this state. When the slat conveyor 10 is transferred to a position where the engagement hole 15 provided in one of the slat plates 11 of the slat conveyor 10 coincides with the pin insertion hole 35 of the base plate 31 of the carriage 30, the position is adjusted by hand pressing. In this state, the connecting pins 35 are inserted into the pin insertion holes 35 provided on the left and right sides of the base plate 31, and the lower ends thereof are engaged with the engaging holes 15. As a result, the carriage 30 is driven by the slat conveyor 10. Further, when the carriage 30 driven by the slat conveyor 10 advances to a predetermined position, the next carriage 30 is sent from the carry-in stage 3 to the work line 4. In the same manner as described above, the carriage 30 is engaged with the slat plate 11 of the slat conveyor 10 by the connecting pin 36.

  As a result of the above operation, the two carriages 30 are carried into the work line 4 at a predetermined interval in the front-rear direction and conveyed by the slat conveyor 10. Then, at a predetermined position on the conveyance start end side of the work line 4, the workpiece 1 is carried into the work line 4 by handling means (not shown) including a crane or a hanger. That is, the workpiece 1 is stably set so as to pass over the workpiece placement portions 33 and 33 of the two carriages 30 and 30 at the front and rear. Here, the distance between the two carriages 30 is made as wide as possible. As a result, the lower position of the workpiece 1 is largely opened, and the workability with respect to the lower surface of the workpiece 1 can be improved.

  Although the work 1 is conveyed along the work line 4, since the wheel 30 of the carriage 30 is located on the rail 20, the gravity of the work 1 is substantially reduced by the rail through the wheel 34 of the carriage 30. 20 will accept. The cart 30 is connected to the slat conveyor 10 by a connecting pin 36. The connecting pin 36 is merely inserted into the pin insertion hole 35 and the engaging hole 15, and the cart 30 is otherwise connected to the slat conveyor 10. On the other hand, since the non-contact state is maintained, the load of the workpiece 1 hardly acts on the slat conveyor 10. Thus, since the slat conveyor 10 does not receive the gravity of the workpiece 1, even if the slat plate 11 constituting the slat conveyor 10 is formed of a thin metal plate, a resin plate or the like, no deformation or the like occurs. .

  The carriage 30 is pulled by the slat conveyor 10, and the workpiece 1 placed on the carriage 30 advances from the start position to the end position of the work line 4. During this time, operations such as assembly of parts are sequentially performed according to a predetermined order. Is called. Here, in the work line 4, the floor surface 2a of the work area 2 is flat, and the surface of the slat plate 11 constituting the slat conveyor 10 and the rolling surface 20a of the rail 20 are substantially the same as this floor surface 2a. As it is flat, it is convenient for transporting parts carts and work tables with casters, etc., and it is possible to carry tools and parts storage boxes etc. as close as possible to the work position. Work becomes possible. Further, the work placing portion 33 of the carriage 30 is supported by the base plate 31 by the pillar 32, and the work 1 is positioned at a high place, and there is a space between the front and rear carriages 30 and 30, The operator can easily dive into the lower part of the workpiece 1 and can smoothly perform operations such as mounting of parts.

  While the wheel 34 rolls on the rail 20 and supports a load, the wheel 34 is pulled by the slat conveyor 10 and travels along the work line 4, and the parts 34 are moved to the workpiece 1 according to a predetermined order. Assembly is performed. When reaching the end position of the work line 4, the work 1 is taken out from the work line 4 by a work transfer means including a crane or a hanger (not shown). Thereafter, the connection pin 36 is extracted from the engagement hole 15 of the slat plate 11 and moved from the pin insertion hole 35 of the base plate 31 to the pin holding hole 37, whereby the connection between the carriage 30 and the slat conveyor 10 is achieved. The carriage 30 is cut off, and the carriage 30 can be moved manually, or can be driven by a driving means such as a cylinder. As a result, the carriage 30 moves from the work line 4 to the carry-out stage 5.

  The carriage 30 that has moved to the carry-out stage 5 is returned to the carry-in stage 3. This is why the underground pit 40 is provided immediately below the work line 4. The underground pit 40 has a length from the position of the work line 4 provided with the slat conveyor 10 to the positions of the carry-in stage 3 and the carry-out stage 5. FIG. 4 shows a configuration of the position of the work line 4 in the underground pit 40, and the underground pit 40 constitutes a return path 41 of the carriage 30 in this portion. FIG. 7 shows the configuration of the underground pit 40 at the position of the carry-out stage 5. In addition, since the position of the carry-in stage 3 in the underground pit 40 has substantially the same configuration as the carry-out stage 5, its illustration is omitted. The underground pit 40 at the position of the carry-out stage 5 and the carry-in stage 3 shifts the carriage 30 up and down between a height position connected to the work line 4 and a height position connected to the return path 41. Part 42 is configured.

  A transition base 42 of the carry-out stage 5 (same for the carry-in stage 3) shown in FIG. 7 is provided with a support base 43 on which one carriage 30 is placed. It is installed. The rotary table 44 is equipped with a rotary actuator (not shown), so that the rotary table 44 can reciprocate 90 degrees in a horizontal state. The rotary table 44 is provided so as to be connected to the lifter 45. The lifter 43 is configured to raise the support base 43 on which the carriage 30 is placed at a height that substantially matches the height of the floor surface 2a of the work area 2. This is for moving up and down between a position (indicated by a two-dot chain line in FIG. 7) and a height position (position indicated by a solid line in FIG. 7) as a return path of the carriage 30.

  The return path 41 shown in FIG. 4 is provided with a return conveyor 46 as a transfer means for moving the carriage 30 so as to return it from the carry-out stage 5 side to the carry-in stage 3 side. The return conveyor 46 is disposed in the underground pit 40 inside the structure portions 47 on the left and right sides of the return path 41. The rails 20 are attached to the upper positions of the structural portions 47. Therefore, when the carriage 30 supporting the workpiece 1 is conveyed along the conveyance path, the loads of the workpiece 1 and the carriage 30 are applied to the rails 20. To the structure portion 47, and finally, the structure portion 47 is received by the base 21 on which the structure portion 47 is erected. Furthermore, the site | part below the conveyance surface in the slat conveyor 10 containing the sprocket 13 is arrange | positioned at the conveyor accommodating part 48 formed in the outer side of the structure parts 47 and 47 which comprise the underground pit 40. FIG.

  With this configuration, the carriage 30 on which the workpiece 1 is placed is pulled by the slat conveyor 10 and is conveyed on the work line 4 from the loading stage 3 side toward the unloading stage 5. Is conveyed at the same height position as the floor surface 2 a, moves to the conveyance end position of the work line 4, and the workpiece 1 is taken out from the carriage 30. Thereafter, the connecting pin 36 of the carriage 30 is detached from the engagement hole 15 provided in the slat plate 11, the traction state of the carriage 30 by the slat conveyor 10 is released, and the carriage 30 is moved to the carry-out stage 5. Two carriages 30 are used to convey one workpiece 1, but the carriage 30 is conveyed at a very small speed by the slat conveyor 10, so that the carriage 30 is fed in order from the carriage 30 on the front side. It can be operated to return another cart 30 after one cart 30 returns.

  Here, in the carry-out stage 5, the support base 43 is disposed at the raised position by the action of the lifter 45, and the carriage 30 is disposed on the support base 43. Therefore, the lifter 45 is lowered. During this time, the rotary table 44 is operated to rotate the support base 43 by 90 degrees in the horizontal direction. Therefore, when the support base 43 is lowered to the height position of the return path 41, the posture of the carriage 30 placed on the support base 43 is changed so as to be turned sideways. Then, after the support base 43 is arranged at the lowest position by the lifter 45, the carriage 30 is transferred to the return conveyor 46 from the state where the carriage 30 is installed on the support base 43 by an appropriate transfer mechanism. Then, by driving the return conveyor 46, the carriage 30 is advanced in the direction opposite to the moving direction of the work line 4 and returned to the carry-in stage 3.

  The carriage 30 that has returned to the carry-in stage 3 in this way moves to the support table 43 in the lifter 45 provided in the carry-in stage 3. In this state, the lifter 45 is lifted, and the rotary table 44 is moved. By rotating 90 degrees, the carriage 30 is oriented in the direction in which the longitudinal direction of the work placing portion 33 is orthogonal to the conveying direction of the slat conveyor 10. Thereafter, the carriage 30 is transferred from the support base 43 to the slat conveyor 10. Next, the other carriage 30 is transferred from the carry-in stage 3 to the slat conveyor 10 in the same manner as described above, so that the workpiece 1 can be again supported by the two carriages 30 and sent to the work line 4. Become.

  Here, when the carriage 30 moves in the conveyance direction of the workpiece 1 along the work line 4, the longitudinal direction of the workpiece placement portion 33 is arranged in a direction orthogonal to the movement direction of the carriage 30. The workpiece 1 can be transported in a stably supported state, and operations such as assembly of parts performed on the workpiece 1 can be performed safely and smoothly. When returning the carriage 30, the carriage 30 is rotated approximately 90 degrees so that the short dimension B side is directed in the conveying direction of the return path 41, so the width of the return path 41 is reduced. Can do. Moreover, in the height direction of the underground pit 40, the position of the conveyor accommodating portion 48 in which the slat conveyor 10 is accommodated and the return path of the carriage 30 can be partially overlapped. Further, the underground pit 40 can be made compact as a whole. Therefore, even if the structure 47 and the foundation 21 are simplified, it is possible to effectively support the load of the work 1 that is a heavy object, and it is possible to inexpensively form equipment constituting the entire line.

It is composition explanatory drawing which shows the work area with which the workpiece conveyance apparatus is equipped. It is a side view which shows the state which is conveying the workpiece | work with a workpiece conveyance apparatus. It is a principal part external view of a workpiece conveyance apparatus. It is sectional drawing in the XX position of FIG. It is a side view of a trolley. It is a top view of a trolley. It is sectional drawing in the YY position of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work 2 Work area 2a Floor surface 3 Carry-in stage 4 Work line 5 Carry-out stage 10 Slat conveyor 11 Slat board 15 Engagement hole 15a Sleeve 20 Rail 30 Carriage 31 Base plate 33 Work mounting part 34 Wheel 35 Pin insertion hole 36 Connecting pin 40 underground pit 41 return path 42 transition part 43 support base 44 rotating table 45 lifter 46 return conveyor 47 structure part 48 conveyor accommodation part

Claims (3)

While the work is transported along the transport path, the necessary work is performed on the work,
Arranging a plurality of carts along the transport path, installing the work on these carts, towed by a transport means,
Each of the carts is configured with a dimension in the left-right direction larger than the dimension in the front-rear direction of the traveling direction in the transport path,
The transport path is provided with a carry-in stage for carrying the cart to a transport start end position and a carry-out stage carried out from the transport end position,
A return path for returning the carriage from the carry-out stage to the carry-in stage is provided at a lower position of the transport path,
The carry-in stage and the carry-out stage are each provided with a lifter that lifts and lowers one carriage between the connection position to the transport path and the connection position to the return path,
The work transfer apparatus according to claim 1, wherein the lifter includes a rotary table on which the carriage is installed and rotated in the horizontal direction by 90 degrees. The slat conveyor is used for the conveyance path, the cart is pulled by the slat conveyor, and the workpiece is conveyed by at least two front and rear carts. Work transfer device. The carriage has a plurality of wheels, and rails are arranged in parallel with the conveyance path. When the carriage is conveyed along the conveyance path, the wheels of the carriage roll on the rail. 2. The workpiece transfer apparatus according to claim 1, wherein the carriage is transferred by transfer means in the return path.

Images