Safety cutting knife

Abstract

Provided is a safety cutter that can be integrally configured with a handle portion and a head portion from resin or the like to simplify the manufacturing process and also does not increase the cutting resistance. The safety cutter is provided with a handle portion (31) made of resin, blades (50a, 50b) that protrude from the handle portion, and a head portion (33a, 33b) made of resin that is disposed at the front end of the protruding blades. The blades are formed with through holes, and a resin-made connecting portion (35) that is located within the through holes connects the handle portion (31) made of resin and the head portion (33a, 33b). With the safety cutter of the present application, since all three components made of resin are connected, a one-gate type molding die can be used, and the manufacturing process can be performed simply and at low cost. In addition, since the thickness of the blades does not unnecessarily increase, the cutting resistance does not increase, and the cut does not become rough.

Description

Technical Field

[0001] This invention relates to a safety cutter capable of safely cutting thick paper and / or rope, etc. Background Technology

[0002] Various solutions have been proposed in the past regarding safety cutting knives capable of safely cutting thick paper and / or rope, etc. (e.g., Patent Documents 1-4). Figure 1 The safety cutting knife shown in Patent Document 1 is illustrated.

[0003] Blades 12a and 12b protrude from the handle 11 for the user to hold, and heads 13a and 13b are provided at the front end of each blade for guidance and protection. The user holds the handle 11 and pulls it forward to cut thick paper or similar materials using one of the blades 12a or 12b.

[0004] Generally, the blades 12a and 12b are made of metal, while the handle 11, head 13a, and head 13b are made of resin. In the manufacture of a safety cutting knife, after the blades are placed in the molding die, the resin to form the handle 11, head 13a, and head 13b is poured into the molding die. Because the handle 11, head 13a, and head 13b are separate (non-connected) resin molded bodies, therefore... Figure 3A As shown in the rough diagram, a molding die with three gates is required.

[0005] Right now, Figure 3A A simplified illustration shows a safety cutter immediately after molding using a three-gating mold. It is understood that each of the three resin sections (11, 13a, 13b) has a runner (resin remaining in the flow path of the mold) protruding from it, thanks to the use of a three-gating mold. This runner is subsequently removed using appropriate methods.

[0006] Generally speaking, compared with the case of using a single-gating mold (described later), the manufacturing time, labor, and cost, including trimming flash, will increase when using a three-gating mold.

[0007] Patent document 4 discloses a safety cutting knife used for the same purpose, but which can be manufactured using a single-gating mold instead of a three-gating mold. That is, as Figure 2 As shown, the safety cutter in Patent Document 4 is an integral piece where the handle portion 11 and the head 13a are connected. In this cutter, the resin portion 14 connecting the handle portion 11 and the head 13a covers the blade, with only the edge 15 of the blade exposed. With this configuration, because the resin-molded parts are integrated, a single-gating mold can be used, thus reducing manufacturing time, labor, and costs.

[0008] However, because the resin part 14 extends over the blade, it increases the cutting resistance during cutting operations, which is another problem. As a result, problems such as difficulty in cutting smoothly, increased hand fatigue, and rough cuts occur.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: US Design Patent USD 784,107S

[0012] Patent Document 2: US Design Patent USD 660,675S

[0013] Patent Document 3: US Design Patent USD 802,394S

[0014] Patent Document 4: US Design Patent USD 527,604S Summary of the Invention

[0015] Technical issues

[0016] The present invention is a solution created in view of the problems of the prior art mentioned above, and its purpose is to provide a safe cutting knife that can be integrally formed from resin or the like to simplify the manufacturing process and does not increase cutting resistance.

[0017] Technical solutions and technical effects

[0018] The safety cutting knife of the present invention includes: a "handle portion", a "blade protruding from the handle portion", and a "head disposed at the front end of the protruding blade". A through hole is formed in the blade, and a connecting portion located within the through hole connects the handle portion to the head.

[0019] Regarding the connecting parts, resin, which is widely used in molding, is preferred, but aluminum, zinc, magnesium, and other metals, which are also used in die casting, are also acceptable.

[0020] In the safety cutting knife of the present invention having the above-described configuration, a connecting portion located within a through hole formed in the blade connects the handle portion to the head. Therefore, it can be manufactured using a single-gating mold, and compared to using a three-gating mold, the mold configuration can be simplified, thus reducing costs. Furthermore, manufacturing time and labor, including trimming burrs immediately after molding, can be reduced, further reducing costs.

[0021] Furthermore, since the connecting part that links the handle to the head is located within the through hole formed in the blade, the overall thickness of the blade is not increased. Therefore, the cutting resistance when cutting thick paper and other objects does not increase, and thus, (compared to the case where the connecting part covers the blade and increases its thickness) the following effects can be achieved: the cutting operation becomes smoother, hand fatigue is reduced, or a rough cut is prevented.

[0022] Furthermore, since the connecting part is located inside the through hole, its durability is higher compared to the case where the connecting part extends along the spine of the blade. That is, it is less likely for the connecting part to break during the use of the safety cutting blade, and thus, it can effectively prevent the broken connecting part from becoming a foreign object and getting into some place.

[0023] In the safety cutter of the present invention, both ends of a blade (embedded in the handle portion) protrude from the handle portion in opposite directions away from each other, and each end portion is provided with a head. In this case, it is preferable that the through hole is formed in the blade and extends from one head to the other head.

[0024] With this configuration, only one blade needs to be placed inside the forming mold to create a safe cutting blade with two cutting sections. Therefore, the arrangement of blades within the forming mold becomes simple, reducing manufacturing time, labor, and costs. Attached Figure Description

[0025] Figure 1 This is an illustration of an example of a conventional safety cutting knife.

[0026] Figure 2 This is another illustration of a conventional safety cutting knife.

[0027] Figure 3A This is a schematic perspective view illustrating the manufacture of a safety cutting blade using a three-gating mold.

[0028] Figure 3B This is a schematic perspective view illustrating the manufacture of a safety cutting blade using a mold with a gate type.

[0029] Figure 4A This is a diagram showing the area near the tip of the safety cutting blade according to the first embodiment of the present invention.

[0030] Figure 4B This indicates that it is configured in Figure 4A A perspective view of the blade in a safety cutting knife.

[0031] Figure 5 This is a perspective view showing the shape of the back of the safety cutting blade of the present invention.

[0032] Figure 6 yes Figure 5 A six-sided view of a safety cutting blade.

[0033] Symbol Explanation

[0034] 11. Handle section

[0035] 12a and 12b blades

[0036] 13a, 13b Head

[0037] 14 Resin Section

[0038] 15 Edge

[0039] 30 Safety Cutting Knives

[0040] 31. Handle section

[0041] 33a, 33b Head

[0042] 35 Connecting parts

[0043] 50, 50a, 50b blades

[0044] 55 long holes Detailed Implementation

[0045] <First Implementation Method>

[0046] The first embodiment of the present invention will now be described with reference to the accompanying drawings. Regarding the first embodiment, the handle portion 31, head 33a, head 33b, and connecting portion 35 are made of resin and manufactured using a molding die.

[0047] Figure 4A This refers to a safety cutting blade 30 according to a first embodiment of the present invention. Regarding the safety cutting blade 30, in... Figure 4A The image only shows the area near its front end, but it is similar to... Figure 1 , 2 The conventional safety cutter shown is also slender in overall shape. The user holds the handle 31 and pulls it forward, using a blade 50a or 50b to cut thick paper, etc.

[0048] It should be noted that, Figure 5 as well as Figure 6 The figure shows an example of the overall shape of the safety cutting blade of the present invention.

[0049] Blades 50a and 50b protrude from both sides of the handle portion 31 (front end area), and each blade has a head 33a and 33b at its front end for guiding and protection. This feature itself is consistent with… Figure 1 The safety cutter shown is the same as the previous one.

[0050] The main feature of this invention is that the blade 50 is provided with an elongated hole (through hole) 55. As a result, as will be explained below, the following effects can be achieved: "a safety cutting blade can be manufactured using a sprue-type molding die", and "the total thickness of the blade is not increased".

[0051] <It can be manufactured using a single-gating mold>

[0052] Figure 4B It means Figure 4A A perspective view of the blade 50 of the safety cutting knife 30. It can be seen that the elongated hole 55 formed in the blade 50 extends from one head 33a to the other head 33b.

[0053] The safety cutter 30 is manufactured by molding, but during manufacturing, the blade 50 is placed in the molding mold beforehand, and resin is poured into the molding mold.

[0054] If a gate-type mold is used, for example, the resin is poured into the cavity corresponding to the handle portion 31 through the gate, the resin flows within the cavity while traveling through the through-hole 55 of the blade, ultimately forming the heads 33a and 33b. After molding is complete, the portion formed by the solidification of the resin remaining in the through-hole 55 is... Figure 4A The connecting part 35 in the middle.

[0055] Thus, there are three resin components (handle 31, head 33a, and head 33b), but since these three components are integrated through the resin connecting part 35, the safety cutter 30 of the present invention can be manufactured using a gate-type molding die.

[0056] Figure 3B This diagram provides a simplified explanation, illustrating the safety cutting blade immediately after molding using a gate-type mold. (This is in accordance with previous technical descriptions.) Figure 3A In contrast, it can be seen that the gating system appears only in one location.

[0057] Generally speaking, compared to using a three-gating mold, using a single-gating mold can reduce manufacturing time, labor, and costs, including shaving off flash. Furthermore, a single-gating mold simplifies mold construction and reduces costs.

[0058] The total thickness of the blade does not increase.

[0059] Moreover, according to Figure 4A , 4BAs shown in the configuration, since the connecting portion 35 connecting the handle portion 31 to the head 33a and the head 33b is housed in the elongated hole (through hole) 55 formed in the blade 50, the thickness of the blade 50 is not increased.

[0060] Suppose if Figure 2 As in the conventional example shown, the resin portion 14 extends by overlapping the blade, thus increasing the total thickness of the blade, which in turn leads to increased cutting resistance and / or a coarser cut. With respect to the safety cutter of the present invention, since the connecting portion 35 is located within the elongated hole 55, the blade thickness remains unchanged (typically, a total thickness of about 0.5 to 0.6 mm), therefore, the cutting resistance does not increase, and the cut does not become rough.

[0061] Furthermore, since the connecting portion 35 is located within the elongated hole 55 (i.e., since the entire circumference of the connecting portion 35 is surrounded by the blade 50), its durability is higher compared to the case where it extends along the spine of the blade 50. However, if we consider the case where the resin portion extends outward along the spine of the blade 50, then during the use of the safety cutter, friction with the material being cut (thick paper and / or rope, etc.) will affect the connecting portion 35. Figure 4A The upward force makes the connection 35 highly susceptible to breakage. In this invention, since the connection 35 is surrounded by the blade 50, such breakage is difficult to occur, and thus, it is also possible to effectively prevent the broken connection 35 from becoming a foreign object and getting mixed in somewhere.

[0062] <Second Implementation Method>

[0063] In the first embodiment, the "handle 31", "heads 33a, 33b" and "connecting part 35" constituting the safety cutter are made of resin and manufactured using a molding die.

[0064] In contrast, in the second embodiment, the safety cutting knife is manufactured by die casting. That is, molten metal (aluminum, zinc, magnesium, etc.) is injected under high pressure into a metal mold installed in a die casting machine and solidified. Therefore, the "handle 31", "heads 33a, 33b", and "connecting part 35" are all made of metal.

[0065] Regarding the second embodiment, it can also be manufactured using a single-gating metal mold, similar to the first embodiment, without increasing the total thickness of the blade. Therefore, the same effects as the first embodiment described above can be achieved.

[0066] Both the first and second embodiments described above can be modified as described below.

[0067] <Variation Example> (1)

[0069] exist Figure 4A , 4B In the illustrated embodiment, blades 50a and 50b protrude laterally from the handle portion 31, and the safety cutter 30 has cutting portions at both locations. The invention is not limited to this configuration; for example, the invention could also be configured with blades protruding only on one side.

[0070] Even in this case, the handle can be connected to the head by a connecting part by providing an appropriate through hole in the blade, and thus, it can be manufactured using a sprue-type molding die. (2)

[0072] exist Figure 4A , 4B In the illustrated embodiment, a blade 50 is embedded within the handle portion 31, with its two ends 50a and 50b protruding towards the sides of the handle portion 31. However, the invention is not limited to this configuration, and two separate blades can also be used to construct a safety cutting knife.

[0073] Furthermore, a safety cutter can be formed that uses three or more individual blades and has three or more cutting sections. In either case, a through hole can be formed in each blade, and a connecting part formed by filling the through hole can be used to connect the handle to the head. Thus, a safety cutter can be manufactured using a single-gating mold.

Claims

1. A safety cutting knife, characterized in that, have: Handle portion (31); Blade (50a, 50b), which protrudes from the handle; as well as The head (33a, 33b) is positioned at the tip of the protruding blade. A through hole (55) is formed in the aforementioned blade. The connecting part (35) located within the through hole (55) connects the handle part to the head part. The two ends (50a, 50b) of a blade (50) protrude from the handle portion (31) in opposite directions away from each other, and each of the two ends is provided with the head (33a, 33b). The aforementioned through hole (55) is formed in one of the blades (50) and extends from one head (33a) to the other head (33b).

2. The safety cutting knife according to claim 1, characterized in that, The aforementioned handle (31), head (33a, 33b) and connecting part (35) are made of resin.

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