FR2877924A1 - Corrugated carton blank for constituting protection corner of goods package, has flutes perpendicular to longitudinal edges of merlons that cover oblong openings, when blank is flat and when sheathings are folded and fixed on outer panels - Google Patents

Abstract

The blank has sheathings (26a, 26b) with notched free longitudinal edges (25a, 25b) and multiple main slots (28a, 28b), so that the sheathings have multiple main merlons (29a, 29b). Each merlon covers oblong openings (27a, 27b), when the blank is flat and that the sheathing is folded up and fixed on outer panels (24a, 24b). Flutes are perpendicular to longitudinal edges of the merlons. An independent claim is also included for a method to form a plate for the constitution of a blank.

Description

Blank and protective angle for a package, as well as a method for

  making a plate, constituting the blank and the angle from the plate.

  The invention relates to a blank and a protective angle for a package, and to a method of producing a plate, constituting a blank and an angle from the plate.

  The delivery of goods requires packaging to protect the goods, adapted to the products, easy to achieve, economical, and ecological.

  Some products are transported in cardboard, wood or plastic boxes that can be placed on pallets.

  In order to maintain one or more crates on a pallet, it is common practice to encircle them, that is, to encircle them with, for example, synthetic tape or thermoformable film.

  This operation often causes damage to the crates at the location of the contact between the crates and the strapping means used, especially at the edges formed by the sides of the crates.

  This damage is most often characterized by a crushing of the edge located under the strapping means or a general torsion of the body.

  In order to solve this problem, it has already been proposed to provide the edges with reinforcements called protective angle.

  One proposed solution is to provide the edges with shapes of polymeric materials. This solution is expensive because it requires the creation of molds specific to the crates transported.

  Another solution is to make corrugated board angles.

  US 4,212,394 discloses an angle formed by a corrugated cardboard blank and comprising, when shaped, three faces determining a trihedron. One of the faces serves as a guide of maintenance to the two other faces, which present, for one of the crenellations, and for the other merlons leaning perpendicularly against the crenellations.

  The setting volume of this bracket causes many difficulties of industrial implementation. The flattening can not be obtained industrially, and when it is done manually, it generates many damages especially at the level of the merlons.

  The document FR 2 673 603 describes an economical solution consisting of a single plate folded and glued on itself so as to form the two wings of the angle, these wings thus comprising a double thickness of cardboard over at least a portion of their width. .

  A gap is formed between the free edges of the two side flaps folded so as to bring the free edge of one of the flaps in the gap during the final shaping of the element to obtain a blocking dihedral volume.

  This solution has several drawbacks: a precarious volume, a difficult and random implementation to get to slide the entire edge of a wing under the edge of the other, and reuse virtually impossible because of the fragility of the together because of the direction of the grooves.

  To this end, the present invention proposes to overcome these drawbacks by providing a protective angle provided with guiding and locking means in the use position, easy to implement both manually and industrially, and allowing the angle iron to be reused several times.

  More specifically, the invention relates to a blank made of cardboard or similar material, delivered flat and intended to be volume for the constitution of an L-shaped protective angle for a package consisting of a single plate having a longitudinal direction, a transverse direction and a given thickness, over which extend a fold line and at least one flap line, longitudinal and parallel, respectively defining two adjacent panels said external by reference to the angle of view of the volume, and at least one so-called doubling panel located at one of the transverse ends of the plate and intended to be folded and fixed on the adjacent external panel, in which at least one oblong slot is arranged in overlap on a section of the fold line, and at least one doubling panel has a free longitudinal edge crenellated and provided with a number of slots said pri such as the doubling panel has as much main beam as lights, each main merlon being arranged to substantially cover a light when the blank is flat and the doubling panel is folded and fixed on the outer panel adjacent thereto .

  The invention also relates to an L-shaped protective angle for a package, obtained from the preceding blank, and which comprises: two adjacent outer panels connected by a fold line and located towards the outside of the form L, - at least one doubling panel located towards the inside of the L shape, folded along a flap line and fixed on the external panel which is (they) is (are) adjacent (s), at least one oblong light disposed overlapping a section of the fold line, and - at least one doubling panel having a free longitudinal edge crenellated and provided with enough so-called main slots so that it (s) has (s) at least a main merlon forcefully inserted into the corresponding oblong slot to lock the angle in the use position.

  The invention also relates to a method of manufacturing a plate for constituting the preceding blank and comprising the steps of: (a) bringing to a cutting station a strip of cardboard or similar material and having a superior longitudinal edge and a lower longitudinal edge corresponding to those of the plate to be constituted; (b) cutting at least the upper longitudinal edge into sufficient main slots to have at least one main merlon; (d) discharging the cut material by applying a distributed thrust force to the material in the main slots; (e) cutting into the material of the strip, oblong lumens in number equal to the number of main merlon, the lumens being arranged overlapping on the fold line so that, on the opposite side to the corresponding merlon, they do not extend only over a width substantially equal to the thickness of the plate; grooving, longitudinally and parallel, the strip along a fold line and at least one flap line to respectively determine two adjacent outer panels and at least one doubling panel located at one of the longitudinal ends of the strip; and (g) transversely cutting the web to the desired blank length.

  The invention also relates to a method of forming the preceding blank, comprising the steps of folding on itself a plate obtained by the above method, by folding the panel (s) of the doubling against the panel external adjacent along the flap lines and (s) maintain in this position by fastening means.

  Finally, the invention also relates to a method of constituting an angle from the previous blank comprising the steps of folding the blank on itself along the fold line so that the outer panels are turned towards the outside. outside the L-shape, and each main merlon forcefully inserted into the corresponding oblong slot to lock the angle in the position of use.

  Particular embodiments of the invention are defined in secondary claims. Other characteristics of the invention will be set forth in the following detailed description with reference to the appended figures which represent respectively: FIG. 1, a diagrammatic plan view of a blank according to the invention after cutting and provided with a crenellated doubling panel; Figure 2 is a schematic plan view of the blank of Figure 1 after bonding the lining panel; (f) FIG. 3, a diagrammatic plan view according to a variant of the invention, after cutting, and provided with two crenellated doubling panels; FIG. 4 is a diagrammatic plan view of the blank of FIG. 3, after gluing the doubling panels; FIGS. 5 to 7 are diagrammatic perspective views of the steps of a method of setting the volume of the blank of FIG. 4; Figure 8 is an enlargement of Figure 7; and in Fig. 9, an enlargement of Fig. 6.

  The blank 10 of Figure 1 is shown flat after cutting a strip or a cardboard plate and has only one thickness e (see Figure 8).

  A fold line 1 and a flap line 2 extend parallel in the longitudinal direction of the blank 10, thus detaching respectively two adjacent external panels 4 and 5, and a so-called doubling panel 6 located at the transverse end of the panel external 5.

  The terms external or internal refer to the blank set volume and determining an L-shaped angle used so that the outer panels are not in direct contact with the box to protect.

  Five oblong slots 7 are arranged overlapping on a section of the fold line 1.

  Six main slots 8 are cut in the free longitudinal edge 15 of the doubling panel 6, thus determining five main merlons transversely aligned with the oblong slots.

  The depth p of the main slots is such that when the doubling panel 6 is folded along the flap line 2 on the outer panel 5 adjacent thereto, the merlons substantially overlap the oblong slots 7 (Figure 2).

  In FIG. 2, the doubling panel 6 has been folded and fixed against the outer panel 5.

  This operation can be done in the factory using for example hot glue or staples.

  The stacking of several blanks IO is done spade to avoid an imbalance of the stack due to the double thickness of cardboard panel doubling panel 6 / outer panel 5 and the simple thickness of cardboard outer panel 4.

  To facilitate storage, the inner face of the outer panel 5 and / or the lining panel 6 may be provided with fixing means activated at the time of use by the user such as double-sided transfer tape, adhesive prolonged effect protected by silicone tape, plastic clips or tape.

  A gap between the edge of the lights 7 and the edge of the merlons 9 has been shown to be relatively large for the sake of clarity in Figure 2, but in reality this space is restricted so that the edges of the merlons and lights are substantially aligned to a few degrees. millimeters. It is the same for Figures 4 and 5.

  The oblong slots 7 have a width 1t substantially equal to the thickness of the plate multiplied by a tolerance factor a in the range from 1.05 to 6, preferably from 1.5 to 3.5, typically from 2 to 3, and the merlon (s) has (s) a width p substantially equal to the thickness e of the plate multiplied by a tolerance factor B in a range of 1.05 to 2, preferably 1 , 1 to 1.7, typically 1.15 to 1.5, and a length LM less than the length LLux of the (the) light (s) oblong (s) by a factor between 0.5 and 0 , 99, preferably 0.8 to 0.95, typically 0.85 to 0.90.

  In the example shown, the width p - of 2 mm on the figurel of the merlons was chosen to be equal to the thickness e of the plate multiplied by a factor B of 1.05; therefore e is 5 mm and was chosen with a factor of 2.63.

  The oblong slots 7 are arranged in overlap on the fold line 1 so that, on the opposite side to the corresponding merlon 9, they extend only over a width If substantially equal to the thickness e of the plate.

  Figures 3 to 9 show another embodiment of the invention in which each of the outer panels 24a and 2411 of a blank 20 is extended respectively along flap lines 22, 23, by a lining panel 26a, 26b adapted to be folded down and held against the outer panels 24a and 241).

  Five oblong slots 27 are arranged in overlap on a section of the fold line 21.

  The two doubling panels 26a, 26b each have a straight longitudinal edge 25a, 25b crenellated and provided with sufficient main slots 28a, 28b so that they have three main merlons 29a, 29b arranged to substantially cover the oblong slots 27a, 27b when the blank 20 is flat and the doubling panels 26a, 26b are folded and attached to the outer panel 24a, 24b adjacent thereto.

  The two lining panels 26a, 26b have merlons 29a, 29b.

  Merlons 29a of a doubling panel 26a are alternately arranged with respect to merlons 29b of the other backing panel 24b, the apertures 27a, 2713 being arranged alternately overlapping on the fold line 21 in such a manner that that, on the side opposite the merlon 29a, 29b corresponding, they extend only on a width lf substantially equal to the thickness of the plate e.

  In addition, each main slot 28a, 28b have a bottom 30a, 30b in which is formed a so-called secondary slot 31a, 31b.

  Advantageously, the secondary crenellations 31a and 31b are respectively located opposite principal merlons 29a and 29b (FIG. 4).

  This facilitates the manufacturing process by limiting the cuts.

  The method according to the invention for producing a blank forming plate 20 comprises the steps of: (a) feeding to the cutting station (not shown) a strip of cardboard or similar material and having a longitudinal edge upper 25a and a lower longitudinal edge 25b corresponding to those of the plate 25 to be formed; (b) cutting the upper longitudinal edge 25a and the lower longitudinal edge 25b into, respectively, four and three main slots, 28a, and 28b, so that they have, respectively, three and two main merlons 29a and 29b; (d) discharging the cut material by applying a distributed thrust force to the material in the main slots 28a, 28b; (e) cutting in the material of the strip, respectively, three and two oblong slots 27a, 27b in number equal to the number of main merlon 29a, 29b, the lights 27a, 27b being arranged alternately overlapping on the fold line 21 so that, on the side opposite the corresponding merlons 29a, 29b, they extend only to a width If substantially equal to the thickness e of the plate; (t) grooving, longitudinally and parallel, the strip along a fold line 21 and two flap lines 22, 23 to respectively determine two adjacent outer panels 24a, 24b and two doubling panels 26a, 26b located at the longitudinal ends of the strip ; and (g) step (a) or (b).

  The method for making the blank of Figures 3 to 9 comprising the further steps of: (c) cutting at least one secondary slot 31a, 3b in the bottom 30a, 30b of each main slot 28a, 28b; and (d) discharging the cut material by applying a distributed thrust force to the material in the main and secondary slots.

  During the manufacture of blank 20, step (c) of the method consists in cutting a secondary slot 31a, 31b in each main slot 28a, 28b, the cutout being located substantially on either side of the axis of symmetry of each main slot 28a, 28h.

  Step (d) is a critical step when cutting blanks. Indeed, the manufacturing is mechanized and the rate of cutting and evacuation must be maximum to improve the profitability of the operation.

  However, when a cut of the order of the thickness of the carton must be made at the edge -as in the embodiment of Figures 1 and 2, the strength of the portion cut transversely the strip to the desired length of blank .

  (f) can be carried out beforehand or concomitantly at the steps between the cut and the edge of the plate has almost no resistance. Therefore, the carton can bend in contact with the cutting tool which, instead of making a sharp and clean cut, may not cut the desired length and / or tear part of the carton. The rigid rubbers used for the expulsion of the falls also constitute a source of tearing of the cardboard. As a result, the cut is confused and there are very often falls still secured to the blank by means of some paper fibers. This type of blank does not have sufficient quality to be sold.

  One solution proposed by the invention is to provide that the direction of the grooves is transverse, that is to say that the grooves are perpendicular to the longitudinal edges of the merlons. This stiffens the merlon and reduces the risk of bad cutting.

  Another solution that can be used alone or in combination with the previous one is to cut secondary slots 31a, 31b in the bottom 30a, 30b of the main slots 28a, 28b to form an upper contact surface with the means of evacuation of the cardboard waste and thus facilitate and improve the evacuation of cardboard waste.

  Thus, the shape of the secondary slots 31a, 31b cut during step (c) is chosen to allow the application, during step (d), of the means of evacuation falls sufficiently wide to perform a push fit to completely evacuate the falls, and that the evacuation means are not torn off when the process is carried out at high speed.

  Only one secondary slot 28a, 28b makes it possible to achieve this result, but it may be advantageous to provide several secondary slots in the bottom of a main slot, especially when the main slots extend over a large width.

  The secondary slots cut in step (c) of the blank manufacturing process may be uniformly distributed with respect to the axis of symmetry of each main slot so that the pushing force applied in step (d) is uniformly distributed. distributed along each main slot.

  The cardboard falls are pushed over their entire length and their evacuation is very effective.

  In addition, the crenellated shape of the cutting line inside the main slots prevents the material close to the edge does bend, thus promoting a clean and precise cutting, effective blocking of the volume blank and an alternation of blocking / unblocking without altering the quality of the blockages as will be explained later.

  To obtain the blank of FIG. 4, a plate obtained by the preceding method must be folded back on itself, by folding the doubling panels 26a, 26b against the adjacent external panel 24a, 24b along the flap lines 22, 23 and holding them in this position by fastening means (32) for example taken from the group consisting of glue, long-acting adhesive, double sided tape, staples, plastic clips and adhesive tape .

  The two wings of the angle are thus constituted.

  Figures 5 to 7 illustrate a method of implementing the blank of Figures 4 and 5 to obtain a protective angle ready for use.

  The wing 35a constituted by the outer panel 24a and the doubling panel 26a is folded towards the wing 35b constituted by the outer panel 24b and the lining panel 26b in the direction of the arrows F1.

  The blank 20 is thus folded on itself along the folding line 21 so that the outer panels 24a, 24b are facing outwardly of the L shape (FIG. 7), and that each main merlon 29a , 29b is forced into the corresponding oblong slot 271 27b to lock the angle in the use position (FIG. 6).

  According to the invention, the locking of the angle at an angle d of about 90 is obtained by the support of the main merlons against the edge of the lights: when one of the wings is folded towards the other, each merlon crosses the corresponding light being guided by the transverse edges thereof, and the longitudinal edges of the light pinch the merlon.

  To improve the strength of the merlons it is preferable to provide that the direction of the grooves 40 (Figure 8) is transverse, that is to say that the grooves are perpendicular to the longitudinal edges of the merlons (Figure 8).

  Blocking a blank comprising only a crenellated doubling panel (for example that of Figures 1 and 2) may be sufficient, but in some cases it is preferable to provide two crenellated doubling panels (Figures 3 to 9).

  Indeed, as shown in Figures 8 and 9, the blockage in this case is improved because it is done in two perpendicular planes: one passing by the edges 42a of the lights 27a against which the merlons 29a are supported, and the one passing through the edge 42b of the lights 27b against which the merlons 29b are supported.

  A structure according to the invention therefore makes it possible to shape the angle easy, effective and robust, but it also makes it easy to unfold and unblock the angle to put it back flat, store it and reuse it.

  FIG. 9 also shows an L-shaped protective angle for packaging comprising: two adjacent external panels 24a, 24b connected by a fold line 21 and situated towards the outside of the L-shape, two lining panels 26a, 261) located inwardly of the L shape, folded along a flap line 22, 23 and attached to the outer panel 24a, 24b adjacent thereto, - overlapping oblong slots 27a, 271) on a section of the folding line 21, and - the two lining panels having a free longitudinal edge 25a, 25b crenellated and provided with main slots 28a, 28b so that they have main merlons 29a, 291) forcibly inserted in the oblong slot 27a, 27b corresponding to block the angle in the use position.

  Furthermore, the invention is not limited to the examples described and shown. It is also possible to consider that: • the blank may have two doubling panels, one of which is castellated, the other having any edge; The tape used for the manufacture of the blanks may have indefinite dimensions and be presented in the form of a coil which is unwound as the blanks are made; The shape of the secondary slots may be rectangular, trapezoidal, triangular, rectangle, curved, etc .; Where the material used, and considered to be similar to corrugated board with respect to use, may be corrugated PVC; Several secondary niches can be cut into one main niche. Thus, for example, step (c) may consist in cutting in each main slot three secondary slots, a secondary slot being located substantially in the middle, and the other two secondary slots being located at the ends of each main slot; The embodiment of FIGS. 1 and 2 may be provided with secondary slots.

Claims (18)

  1. Cardboard blank or similar material, delivered flat and intended to be volume for the constitution of an L-shaped protective angle for a package, consisting of a single plate having a longitudinal direction, a transverse direction and a given thickness, over which extends a longitudinal and parallel fold line (1, 21) and at least one flap line (2, 22, 23) respectively defining two adjacent said external panels (4, 5, 24a, 24b) with reference to the volume-setting angle, and at least one said doubling panel (6, 26a, 26b) located at one of the transverse ends of the plate and intended to be folded and fixed on the outer panel (5, 24a, 24b) adjacent thereto, characterized in that at least one oblong slot (7, 27a, 27b) is arranged overlapped on a section of the fold line (1, 21) , and at least one doubling panel (6, 26a, 26b) has an edge free longitudinal axis (15, 25a, 25b) crenellated and provided with a number of so-called main slots (8, 28a, 28b) such that the doubling panel has as many principal merlon (9, 29a, 29b) as lights (7, 29a, 29b) , 27a, 27b), each main merlon (9, 29a, 29b) being arranged to substantially cover a lumen (7, 27a, 27b) when the blank (1, 20) is flat and the doubling panel (6, 26a, 26b) is folded and fixed on the outer panel (5, 24a, 24b) adjacent thereto.   The blank (20) of claim 1, wherein each of the outer panels (24a, 24b) is extended along flap lines (22, 23) by a replaceable backing panel (26a, 26b). folded down and held against the outer panels (24a, 24b).   3. blank (10, 20) according to any one of the preceding claims, wherein the oblong lights (7, 27a, 271)) have a width (lt) substantially equal to the thickness of the plate multiplied by a factor of tolerance (a) in a range of 1.05 to 6, preferably 1.5 to 3.5, typically 2 to 3, and the merlons (9, 29a, 29b) have a substantially equal width (p) the thickness CO of the plate multiplied by a tolerance factor (B) in a range from 1.05 to 2, preferably from 1.1 to 1.7, typically from 1.15 to 1.5, and a length (LM) less than the length (LLUx) of the oblong slots (7, 27a, 27b) by a factor of between 0.5 and 0.99, preferably 0.8 to 0.95, typically of 0, 85 to 0.90.   A blank (10, 20) according to any one of the preceding claims, wherein the oblong slots (7, 27a, 271) are arranged overlappingly on the fold line so that on the opposite side to the merlon (9 , 29a, 29h), they extend only over a width (If) substantially equal to the thickness (e) of the plate.   5. Flan (20) according to any one of the preceding claims, wherein the two lining panels (26a, 26b) have merlons (29a, 29b).   6. Flan (20) according to the preceding claim, wherein the merlons (29a) of a lining panel (26a) are arranged alternately with respect to the merlons (29b) of the other lining panel (26b), the lights (27a, 27b) being arranged alternately overlappingly on the fold line (21) so that, on the opposite side to the merlon (29a, 29b) corresponding, they extend only over a width (If) substantially equal to the thickness (e) of the plate.   7. Flan (20) according to any one of the preceding claims, wherein each main slot (28a, 2811) have a bottom (30a, 30b) in which is formed at least one said secondary slot (31a, 3 lb).   A blank (10, 20) as claimed in any one of the preceding claims, wherein the fastening means is taken from the group consisting of glue, long-acting adhesive, double sided tape, staples , plastic clips and tape.   9. L-shaped protective edge for a package, obtained from a blank (10, 20) according to any one of claims 1 to 8, characterized in that it comprises: two adjacent outer panels (4 , 5, 24a, 24b) connected by a fold line (1, 21) and located outwardly of the L shape, - at least one doubling panel (6, 26a, 26b) located towards the interior of the L shape, folded along a flap line (2, 22, 23) and fixed on the outer panel (5, 24a, 24b) which is (their) are adjacent, at least one oblong slot (7, 27a, 27b) arranged overlapping a section of the fold line (1, 21), and at least one doubling panel (6, 26a, 26b) ) having a free longitudinal edge (15, 25a, 25b) crenellated and provided with sufficient so-called main slots (8, 28a, 28b) so that the doubling panel has at least one main core (9, 29a, 29b) inserted into force in the oblong light (7, 27a, 27b ) to lock the angle in the position of use.   10. A process for producing a blank forming plate (10, 10) according to claim 1, comprising the steps of: a cutting station a strip of cardboard or similar material and having an upper longitudinal edge (15, 25a) and a lower longitudinal edge (25b) corresponding to those of the plate to 15 constitute; (b) cutting at least the upper longitudinal edge (15, 25a, 25b) into sufficient main slots (8, 28a, 28b) to have at least one main merlon (9, 29a, 29b); (d) discharging the cut material by applying a thrust force distributed over the material in the main slots (8, 28a, 28b); (e) cutting into the material of the strip, oblong slots (7, 27a, 27b) in number equal to the number of main merlon (9, 29a, 29b), the lights (27a, 271) being arranged in overlap on the fold line (1, 21) so that, on the opposite side to the corresponding merlon, they extend only over a width (1 f) substantially equal to the thickness (e) of the plate; (f) grooving, longitudinally and in parallel, the strip along a fold line (1, 21) and at least one flap line (2, 22, 23) to respectively determine two adjacent outer panels (4, 5, 24a, 24b) and at least one doubling panel (6, 26a, 26b) located at one of the longitudinal ends of the strip; and (g) transversely cutting the web to the desired blank length.   11. Method according to the preceding claim for forming a blank (20) according to claim 7, comprising the additional steps of: (c) cutting at least one secondary slot (31a, 31b) in the bottom (30a, 30b) ) of each main slot (28a, 28b); and (d) discharging the cut material by applying a distributed thrust force to the material in the main (28a, 28b) and secondary (31a, 31h) slots.   12. Method according to the preceding claim, wherein the shape of the secondary slot (s) (s) (3la, 3 lb) cut (s) in step (c) is chosen to peiinettre application, when in step (d), means for evacuating the falls sufficiently wide to perform a thrust able to completely evacuate the falls, and so that the evacuation means are not torn off when the method is carried out at high speed.   13. A method according to any one of claims 11 or 12, wherein the or the second (s) (s) (s) (31a, 31b) cut (s) O during step (c) are uniformly distributed relative to to the axis of symmetry of each main slot (28a, 28b) so that the pushing force applied in step (d) is uniformly distributed along each main slot (28a, 28b).   14. Method according to the preceding claim, wherein step (c) comprises cutting a secondary slot (31a, 31b) in each main slot (28a, 28b), the cutout being located substantially on either side of the axis of symmetry of each main slot (28a, 28b).   15. Method according to the preceding claim, wherein step (c) consists in cutting in each main slot three secondary slots, a secondary slot being located substantially in the middle, and the other two secondary slots being located at the ends of each main slot. .   16. A method of forming a blank (10, 20) according to any one of claims 1 to 8, comprising the steps of folding on itself a plate obtained by the method according to any one of claims 9 to 14, by folding the doubling panel (s) (6, 26a, 26b) against the adjacent outer panel (5, 24a, 24b) along the flap lines (2, 22, 23) and holding it (s) in this position by fixing means.   17. Method according to the preceding claim, wherein the fastening means are taken from the group consisting of glue, long-acting adhesive, double-sided tape, staples, plastic clips and tape.   A method of forming an angle bracket from a blank (10, 20) according to any one of claims 1 to 8, comprising the steps of folding the blank (10, 20) on itself along of the folding line (1, 21) so that the outer panels (4, 5, 24a, 24b) are facing outwardly of the L shape, and that each main merlon (9, 29a, 29b) is forcibly inserts into the corresponding oblong slot (7, 27a, 27b) to block the position of use.