JP6550975B2 - Assembly jig - Google Patents

Description

  The present invention relates to an assembly jig.

  When using metal screws or bolts (hereinafter simply referred to as “screws”) for assembling electronic devices, etc., they are made of resin such as nylon so that the case (mainly the painted surface) is not wrinkled. The ring shaped spacer may be screwed on.

  In such a case, in consideration of workability, it is preferable to fit the spacer to the screw in advance instead of fitting the spacer to the screw when screwing. The hole diameter of the spacer used for such an application is set to be slightly smaller than the diameter of the screw shaft. Therefore, when the shaft portion of the screw is pressed into the hole of the spacer, the spacer is less likely to be removed from the screw.

  Conventionally, jigs for aligning screws have been proposed (see, for example, Patent Documents 1 and 2).

JP-A-8-39447 Japanese Patent Application Publication No. 2002-18650

  Conventionally, the work of attaching the spacer to the shaft portion of the screw has been complicated, and the workability has been poor.

  An object of the disclosed technology is to provide an assembly jig capable of improving the working efficiency of the work of attaching a spacer to the screw shaft.

According to one aspect of the disclosed technology, a frame, a pair of swing blocks swingably disposed in the frame, and a pair of swing blocks are respectively formed and aligned by sandwiching a screw. possess a recess, the pair of the swing block, the lower inclined by its own weight in the initial state is brought into contact with each other, in a state of being aligned across the screw lower portion of the pair of swing block of the screw When the screw is pressed from above in a state of being in contact with the shaft and aligned across the screw, the screw slides in the recess and swings to an angle through which the screw passes, and after the screw passes The assembly jig which returns to the said initial state by dead weight is provided.

  According to another aspect of the disclosed technology, a spacer receiving block provided with a recess in which a ring-shaped spacer is disposed, a screw receiving block disposed on the spacer receiving block and aligning screws; A screw pressing block having a push rod for pressing a screw aligned with the screw receiving block and inserting the shaft portion of the screw into the hole of the spacer, the screw receiving block including a frame portion and an inner portion of the frame portion. There is provided an assembly jig having a pair of swing blocks arranged so as to be swingable, and a recess formed in each of the pair of swing blocks and aligned with the screw interposed therebetween.

  According to the assembly jig pertaining to the one aspect described above, the work efficiency of the work of attaching the spacer to the screw shaft can be improved.

FIG. 1 is a perspective view showing an example of a jig for attaching a spacer to a screw. FIG. 2 is a perspective view showing a method of using the jig shown in FIG. FIG. 3 is a perspective view showing an assembly jig according to the embodiment. FIG. 4 is a perspective view of a screw receiving block. FIG. 5 is an exploded view of a screw receiving block. FIG. 6 (a) is an enlarged perspective view showing a part of the rocking block disposed in the frame portion of the screw receiving block, and FIG. 6 (b) is a side view of the rocking block. FIG. 7 is a diagram illustrating a state in which the assembly jig according to the embodiment is attached to the hand press. FIGS. 8 (a) to 8 (d) are diagrams (part 1) for explaining a spacer mounting method. FIGS. 9A to 9C are diagrams (part 2) for explaining a method of attaching a spacer. FIGS. 10A and 10B are views (No. 3) for explaining the spacer mounting method. FIG. 11 is a diagram (part 4) for explaining the spacer mounting method. FIGS. 12 (a) to 12 (d) are diagrams (part 5) for explaining the spacer mounting method. FIGS. 13 (a) and 13 (b) are diagrams (part 6) for explaining a method of attaching a spacer. Fig.14 (a)-(c) is a figure (the 7) explaining the spacer attachment method. FIG. 15 is a diagram showing the size of each part of the swing block used for examining the position of the rotating shaft. FIG. 16 is a diagram showing position candidates of the rotation axis of the rocking block. FIG. 17 is a diagram (No. 1) simulating whether or not a screw can pass between swing blocks. FIG. 18 is a diagram (No. 2) simulating whether or not a screw can pass between the swing blocks. FIG. 19 is a diagram (No. 3) simulating whether or not a screw can pass between swing blocks. FIG. 20 is a diagram (No. 4) simulating whether or not a screw can pass between the swing blocks. FIG. 21 is a diagram (No. 5) simulating whether or not a screw can pass between the swing blocks. FIG. 22 is a diagram (No. 6) simulating whether or not a screw can pass between the swing blocks. FIG. 23 is a perspective view showing an example of a screw receiving block having a plurality of pairs of rocking blocks.

  Hereinafter, before describing the embodiment, a preliminary matter for facilitating understanding of the embodiment will be described.

  FIG. 1 is a perspective view showing an example of a jig for attaching a spacer to a screw, and FIG. 2 is a perspective view showing how to use the jig shown in FIG.

  In the jig 10 shown in FIG. 1, a recess 11 a having a size corresponding to the spacer 15 and a hole 11 b penetrating downward from the central portion of the recess 11 a are provided.

  When attaching the spacer 15 to the screw 12, first, the spacer 15 is disposed in the recess 11. Thereafter, as shown in FIG. 2, the shaft 12 b of the screw 12 is vertically placed on the spacer 15, and the hole of the spacer 15 is aligned with the shaft 12 b of the screw 12.

Then, the head 12 a of the screw 12 is vertically pressed by the driver 13 (or another tool), and the shaft 12 b of the screw 12 is pushed into the hole of the spacer 15. Thus, the spacer 15 can be attached to the screw 12.

  When attaching the spacer 15 to the screw 12, the operator holds the screw 12 with a finger as shown in FIG. However, if the shaft portion 12b is inclined with respect to the spacer 15, a large force is required to push the shaft portion 12b into the spacer 15, or the driver 13 is disengaged from the head portion 12a of the screw 12 to injure the finger. There is a risk of In addition, when the driver 13 is pushed in, a finger may be caught between the head 12 a of the screw 12 and the jig 10.

  Therefore, the work of attaching the spacer to the screw needs to be performed with care, which is complicated and the workability is bad.

  In the following embodiments, an assembly jig that can easily attach a spacer to a screw will be described.

(Embodiment)
FIG. 3 is a perspective view showing an assembly jig according to the embodiment. 4 is a perspective view of the screw receiving block, and FIG. 5 is an exploded view of the screw receiving block.

  The assembly jig 20 which concerns on this embodiment has the spacer receiving block 21, the screw receiving block 22, and the screw pushing block 23, as shown in FIG.

  The spacer receiving block 21 is a member having a substantially rectangular parallelepiped shape, and is provided with a circular recess 31 for arranging the spacer 15 and a hole 32 penetrating from the center of the recess 31 to the bottom surface. The diameter of the recess 31 is substantially equal to the diameter of the spacer 15, and the diameter of the hole 32 is set larger than the diameter of the shank of the screw 12.

  The assembling jig 20 according to the present embodiment is to attach the spacer 15 to the two screws 12 at the same time, and the spacer receiving block 21 is provided with two sets of the recess 31 and the hole 32.

  The screw receiving block 22 is disposed on the spacer receiving block 21. As shown in FIG. 4 and FIG. 5, the screw receiving block 22 has a rectangular cylindrical frame portion 41 and a pair of rocking blocks 42 a and 42 b disposed in the frame portion 41. The swing blocks 42 a and 42 b are swingably supported between the two side walls of the frame portion 41 by the rotating shaft 43. Further, between the inner wall of the frame portion 41 and the rocking blocks 42a and 42b, a ring-shaped spacer 44 through which the rotating shaft 43 is inserted is disposed.

  Although details will be described later, when two screws 12 are inserted into the screw receiving block 22 and vibration is applied several times, those screws 12 are sandwiched between the swinging blocks 42a and 42b and vertically aligned.

  The screw block 23 has two push rods 35 for pushing the heads of the two screws 12 aligned in the screw block 22 respectively. The screw block 23 is attached to a pressure bar 55 (see FIG. 7) of a hand press 50 described later with the tip of the push rod 35 down and is disposed above the screw block 22.

  Hereinafter, the screw receiving block 22 will be described in more detail.

  6A is an enlarged perspective view showing a part of the swing blocks 42a and 42b disposed in the frame portion 41 of the screw receiving block 22, and FIG. It is a side view of 42b.

  As shown in FIG. 6 (a), the rocking block 42a is provided with a recess 45a shaped to follow a curved surface of a cone, and the rocking block 42b is provided with a recess 45b shaped to follow a curved surface of a cone . Then, the concave portions 45 a and 45 b are combined to form a truncated cone-shaped screw receiving portion 45 vertically aligned with the screw 12 interposed therebetween.

  In the present embodiment, two pairs of screw receiving portions 45 are formed by the pair of rocking blocks 42a and 42b. The upper diameter of the screw receiving portion 45 is set to be slightly larger than the diameter of the head portion 12a of the screw 12, and the lower diameter of the screw receiving portion 45 is set to be approximately equal to the diameter of the shaft portion 12b of the screw 12. Ru.

  As described above, the rocking blocks 42a and 42b rock with the rotary shaft 43 as a fulcrum, but in the stationary state, the rocking blocks 42a and 42b are inclined inward as shown in FIG. Come in contact with each other.

  Further, in a state in which the screw 12 is interposed between the rocking blocks 42a and 42b (the screw receiving portion 45), the upper surfaces of the rocking blocks 42a and 42b are substantially horizontal. At this time, the central axis of the screw receiving portion 45 is vertical. The shapes of the rocking blocks 42a and 42b when viewed from the rotary shaft 43 side are substantially right-angled isosceles triangles (each corner is chamfered), and the base with respect to the horizontal plane (right-angled isosceles triangles) The longest side) angle is approximately 45 °.

  By forming the rocking blocks 42a and 42b in such a shape, the rocking blocks 42a and 42b are rocked in the narrow space of the frame 41 until the curved surfaces of the recessed portions 45a and 45b are substantially perpendicular to the horizontal plane. Can.

  FIG. 7 is a view showing a state in which the assembly jig 20 according to the present embodiment is attached to the hand press 50. As shown in FIG. Moreover, FIGS. 8-14 is a figure explaining the spacer attachment method. Hereinafter, a method of attaching the spacer 15 to the screw 12 will be described with reference to FIGS. 7 and 8 to 14.

  First, as shown in FIG. 7, the screw pressing block 23 is attached to the pressure bar 55 of the hand press machine 50. Further, the spacer receiving block 21 is disposed on the stage 51 of the hand press machine 50.

  A positioning block 52 is arranged in advance on the stage 51 of the hand press machine 50, and the spacer receiving block 21 is arranged at a predetermined position on the stage 51 by bringing the spacer receiving block 21 into contact with the positioning block 52. Ru.

  Next, as shown in FIG. 8A, the spacer 15 is disposed in the recess 31 of the spacer receiving block 21.

  On the other hand, as shown in FIG. 8 (b), two screws 12 are inserted into the screw receiving block 22. At this time, the screws 12 may simply be placed on the rocking blocks 42a and 42b, and it is not necessary to align them.

  Next, as shown in FIG. 8C, vibration is applied by, for example, shaking the screw receiving block 22 left and right. Since the center of gravity of the screw 12 is on the side of the shaft portion 12 b (see FIG. 1), when the screw receiving block 22 is vibrated, the shaft portion 12 b of the screw 12 is on the lower side. Moving. And as shown in FIG.8 (d), the screw 12 is vertically aligned in the state pinched | interposed between a pair of rocking | fluctuation block 42a, 42b.

  The schematic views of FIGS. 9A to 9C sequentially show the movement of the screw 12 moving by vibration to vertically align the rocking blocks 42a and 42b. As shown in FIGS. 9A to 9C, as the rocking blocks 42a and 42b interlock with the movement of the screw 12, the screw 12 is vertically aligned between the rocking blocks 4a and 42b.

  Next, as shown in FIG. 10A, the screw receiving block 22 in which the screws 12 are aligned is disposed on the spacer receiving block 21. At this time, when the shaft portion 12b of the screw 12 contacts the spacer 15, the screw 12 may be inclined. Therefore, as shown in the cross-sectional view of FIG. 11, the lower end of the shaft portion 12 b of the screw 12 is preferably located slightly above the spacer 15.

  Further, in the present embodiment, as shown in FIG. 11, a notch 41 a is provided at the lower inside of the frame portion 41. By simply fitting the spacer receiving block 21 to the inside of the notch 41a, alignment of the shaft portion 12b of the screw 12 held by the screw receiving block 22 and the hole of the spacer 15 disposed in the spacer receiving block 21 is achieved. Complete. The notch 41a is an example of a positioning mechanism.

  Next, the operator operates the lever 53 (see FIG. 7) of the hand press 50 to move the screw pushing block 23 downward as shown in FIG. 10 (b).

  12A to 12D schematically show each process from the start of the downward movement of the screw pushing block 23 (the push rod 35) to the completion of the attachment of the spacer 15.

  FIG. 12 (a) shows the moment when the push rod 35 of the screw pushing block 23 contacts the head 12a of the screw 12 aligned between the swinging blocks 42a and 42b. As shown in FIG. 12A, when the push rod 35 presses the head 12a of the screw 12, the rocking blocks 42a and 42b rock and the screw 12 moves downward.

In a state where the swing block 42a, the screw 12 between 42b are vertically aligned, as shown in FIG. 13 (a), shank 12 b is swing block 42a of the screw 12, the lower end of 42b (FIG. 13 (a ) Is in contact with a portion shown by a broken circle). Therefore, when the screw 12 moves downward, a rotational force around the rotation shaft 43 is generated in the rocking blocks 42a and 42b as shown by the arrow A in FIG. 13B.

  When the screw 12 further moves downward by the pressing of the push bar 35, the head 12a of the screw 12 moves downward while sliding on the curved surface of the screw receiving portion 45 (the curved surfaces of the recesses 45a and 45b shown in FIG. 6). As a result, as shown in FIG. 12 (b), the rocking blocks 42a and 42b further rotate, and the concave portions 45a. The curved surface 45b is almost perpendicular to the horizontal plane. As a result, the head 12a of the screw 12 can pass through the gap between the swinging blocks 42a and 42b (the gap between the concave portions 45a and 45b). Further, the downward movement of the screw 12 causes the shaft portion 12 b of the screw 12 to pass through the hole of the spacer 15.

  FIG.12 (c) has shown the state which the push bar 35 moved to the lower end. When the push rod 35 is further moved downward from the state shown in FIG. 12 (b), the tip end of the push rod 35 passes between the swing blocks 42a and 42b as shown in FIG. 12 (c). Then, while the push bar 35 moves to the lower end, the shaft portion 12 b of the screw 12 is further pushed into the hole of the spacer 15, and finally the spacer 15 is disposed in the vicinity of the head portion 12 a of the screw 12.

  FIG. 12D shows a state in which, after the spacer 15 is attached to the screw 12, the push rod 35 (screw push block 23) is raised above the swing blocks 42 a and 42 b (screw receiving block 22). .

  As shown in FIG. 12 (d), when the screw pushing block 23 is moved above the rocking blocks 42a and 42b, the rocking blocks 42a and 42b return to their original state (see FIG. 6 (b)) by their own weight.

  Thus, after moving the screw pushing block 23 above the rocking blocks 42a and 42b, the screw receiving block 22 is removed from the spacer receiving block 21 and the spacer receiving block 21 is removed from the stage 51 of the hand press 50. . 14 (a) shows the spacer receiving block 21 removed from the hand press 50. FIG.

  Next, as shown in FIG. 14 (b), the screw 12 on which the mounting of the spacer 15 is completed is removed from the spacer receiving block 21. Thus, the work of attaching the spacer 15 to the screw 12 is completed. FIG. 14 (c) shows the screw 12 to which the spacer 15 is attached.

  As described above, the assembling jig 20 according to the present embodiment can vertically align the screws 12 simply by inserting the screws 12 into the screw receiving block 22 and applying vibration. Then, simply by mounting the screw receiving block 22 on the spacer receiving block 21, the alignment between the shaft portion 12 b of the screw 12 and the hole of the spacer 15 is completed. Moreover, in this embodiment, since the spacer 15 is attached to the screw 12 using the hand press machine 50, it is not necessary for the operator to hold the screw 12 with a finger as shown in FIG. There is no fear.

  These things combine and work of spacer attachment work compared with a case where a worker holds screw 12 with a finger as shown in Drawing 2 by using assembly jig 20 concerning this embodiment The effect is to significantly improve the efficiency.

  By the way, in the present embodiment, it is important to appropriately determine the position of the rotation axis of the rocking blocks 42a and 42b. Hereinafter, a method of determining the position of the rotation axis will be described.

  FIG. 15 shows the size (in mm) of each part of the rocking blocks 42a and 42b used to study the position of the rotation shaft. A black dot indicated by C in FIG. 15 indicates the position of the center of gravity of the swing blocks 42a and 42b. Here, straight lines are drawn horizontally and vertically at 0.5 mm pitch on the side surfaces of the rocking blocks 42a and 42b, and their intersection point is used as a position candidate of the rotation axis, and among these position candidates, the optimum position of the rotation axis is selected. To explore.

  As described above, in order for the rocking blocks 42a and 42b to rock in the desired direction when the screw 12 is pressed by the push rod 35, the lower ends of the rocking blocks 42a and 42b are the shaft 12b of the screw 12. It is important to be in contact with (see FIG. 13 (a)). For that purpose, it is necessary that the rotation axis is above the position of the center of gravity C and on the center of the rocking blocks 42a and 42b (indicated by a dashed line in FIG. 15) than the position of the center of gravity C It becomes a condition.

  However, in consideration of the shaft diameter of the rotary shaft, it is difficult to form a hole through which the tip of the rotary shaft passes within 1.5 mm from the center side edge of the rocking blocks 42a and 42b. Therefore, here, eight points indicated by A1 to A4 and B1 to B4 in FIG. 16 are set as position candidates of the rotation axis of the rocking blocks 42a and 42b.

  The inventors of the present application simulated and examined whether or not the screw 12 can pass between the rocking blocks 42a and 42b for these rotational axis position candidates. However, the diameter of the head of the screw 12 was 9.0 mm, and the diameter on the lower side of the screw receiving portion 45 (see FIG. 6) was 4.0 mm.

  When the diameter (hereinafter referred to as “opening diameter”) of the screw receiving portion 45 (see FIG. 6) is 9.0 mm, 10.5 mm, and 11.0 mm, the screw is It was examined whether 12 could pass between the swinging blocks 42a and 42b.

  In FIG. 17, with the opening diameter of 9.0 mm, with each point of A1 to A4 as the position of the rotation axis, can a screw with a diameter of 9.0 mm of the head pass between the swing blocks 42a and 42b? It is the figure which simulated whether or not. Further, in FIG. 18, with the opening diameter of 9.0 mm and each point of B1 to B4 being the position of the rotation axis, a screw of 9.0 mm in diameter of the head passes between the swinging blocks 42a and 42b. It is the figure which simulated whether it could be.

  As can be seen from FIGS. 17 and 18, when the diameter of the opening is 9.0 mm, the screw remains on the rocking blocks 42 a and 42 b regardless of the position of the rotation shaft A1 to A4 or B1 to B4. I can not go through it.

  In FIG. 19, assuming that the diameter of the opening is 10.5 mm and each point of A1 to A4 is the position of the rotation axis, can a screw with a diameter of the head of 9.0 mm pass between the swinging blocks 42a and 42b? It is the figure which simulated whether or not. FIG. 20 shows that the diameter of the opening is 10.5 mm, each point B1 to B4 is the position of the rotation axis, and a screw having a head diameter of 9.0 mm passes between the swing blocks 42a and 42b. It is the figure which simulated whether it could be.

  From FIGS. 19 and 20, it can be understood that when the rotation axis is at the position of A1 or B1 when the diameter of the opening is 10.5 mm, the screw can pass between the rocking blocks 42a and 42b.

  FIG. 21 shows that the diameter of the opening is 11.0 mm, each point A1 to A4 is the position of the rotation axis, and a screw having a head diameter of 9.0 mm can pass between the swing blocks 42a and 42b. It is the figure which simulated whether or not. FIG. 22 shows that the opening diameter is 11.0 mm, each point B1 to B4 is the position of the rotation axis, and a screw having a head diameter of 9.0 mm passes between the swing blocks 42a and 42b. It is the figure which simulated whether it could be.

  21 and 22, when the opening diameter is 11.0 mm, the screw can pass between the swing blocks 42a and 42b when A1, A2 or B1 is positioned at the rotation axis.

  That is, when the diameter of the opening is 10.5 mm, the position of the rotation shaft may be A1 or B1, and when the diameter of the opening is 11.0 mm, the position of the rotation shaft may be A1, A2 or B1.

  In the above-described embodiment, the assembly jig 20 for attaching the spacer 15 to the two screws 12 at the same time has been described. However, for example, as shown in FIG. 23, a screw receiving block 62 having a plurality of pairs of rocking blocks 42a and 42b, a spacer receiving block 61 corresponding to the screw receiving block 62, and a screw pushing block (not shown) are used. You may This allows the spacers to be attached to more screws 12 simultaneously.

  Further, the following appendices will be disclosed regarding the above embodiments.

(Appendix 1) A frame part;
A pair of rocking blocks arranged swingably in the frame;
An assembly jig comprising: a recess formed on each of the pair of rocking blocks and arranged to sandwich and align a screw.

  (Additional remark 2) The said recessed part is a shape which follows the curved surface of a cone, The assembly jig | tool of Additional remark 1 characterized by the above-mentioned.

  (Supplementary Note 3) The assembly jig according to Supplementary note 2, wherein the pair of rocking blocks are rocked at least to an angle through which the screw passes.

  (Supplementary note 4) The assembly jig according to supplementary note 3, wherein the pair of oscillating blocks has a truncated cone-shaped central axis formed by the concave portion in a stationary state.

  (Supplementary Note 5) The assembling jig according to any one of Supplementary notes 1 to 4, wherein a shaft portion of the screw and the swing block contact with each other when the screws are aligned.

  (Additional remark 6) The position of each rotating shaft of said pair of rocking | fluctuation block is located above the gravity center position of each rocking | fluctuation block, and is located inside each gravity center position, Additional remark 1 thru | or 5 characterized by the above-mentioned. The assembly jig according to any one of the above.

  (Supplementary Note 7) In the initial state, the pair of rocking blocks are inclined due to their own weight, and the lower parts are in contact with each other, and in the state in which the lower parts of the pair of rocking blocks are aligned with the screw interposed therebetween When the screw is pressed from above in a state where the screw is in contact with the screw and aligned, the screw slides to the recess and pivots to an angle at which the screw passes through, and after the screw passes by its own weight The assembly jig according to claim 1, wherein the initial state is returned.

(Supplementary Note 8) A spacer receiving block provided with a recess in which a ring-shaped spacer is disposed,
A screw receiving block disposed on the spacer receiving block to align the screws;
A screw pushing block provided with a push rod for pushing a screw aligned with the screw receiving block to insert an axial portion of the screw into a hole of the spacer;
The screw receiving block is
A frame,
A pair of rocking blocks arranged swingably in the frame;
An assembly jig comprising: a recess formed on each of the pair of rocking blocks for aligning the screws.

  (Additional remark 9) The said recessed part is a shape which follows the curved surface of a cone, The assembly jig of Additional remark 8 characterized by the above-mentioned.

  (Supplementary note 10) The assembling jig according to supplementary note 8 or 9, further comprising a positioning mechanism for arranging the screw receiving block at a predetermined position on the spacer receiving block.

  (Supplementary note 11) The assembly jig according to any one of supplementary notes 8 to 10, wherein the screw pushing block is attached to a hand press machine.

12: screw, 12a: head, 12b: shaft portion, 15: spacer, 20: assembly jig, 21, 61: spacer receiving block, 22, 62: screw receiving block, 23: screw pushing block, 31: recess, DESCRIPTION OF SYMBOLS 32 ... Hole 35 A push rod 41 Frame part 42a, 42b A rocking block 43 Rotary shaft 45 Screw receiving part 45a 45b A recessed part 50 Hand press machine 51 Stage 52 ... positioning block, 53 ... lever, 55 ... pressure bar.

Claims (3)

A frame,
A pair of rocking blocks arranged swingably in the frame;
Is formed on each of the pair of swing block, possess a recess to align across the screw,
In the initial state, the pair of rocking blocks are inclined due to their own weight and the lower portions are in contact with each other, and the lower portions of the pair of rocking blocks are in contact with the shaft portion of the screw in the aligned state sandwiching the screws. When the screw is pressed from above in a state in which the screw is sandwiched and aligned, the screw slides in the recess and swings to an angle through which the screw passes, and after the screw passes, the screw is pushed to its initial state by its own weight Assembly jig characterized by returning .   The assembly jig according to claim 1, wherein the recess is shaped to follow a curved surface of a cone. A spacer receiving block provided with a recess in which a ring-shaped spacer is disposed;
A screw receiving block disposed on the spacer receiving block to align the screws;
A screw pushing block provided with a push rod for pushing a screw aligned with the screw receiving block to insert an axial portion of the screw into a hole of the spacer;
The screw receiving block is
A frame,
A pair of rocking blocks arranged swingably in the frame;
An assembly jig comprising: a recess formed on each of the pair of rocking blocks for aligning the screws.

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