One of the oldest and most widely u

One of the oldest and most widely used writing utensils, the pencil originated in pre-historic times when chalky rocks and charred sticks were used to draw on surfaces as varied as animal hides and cave walls. The Greeks and Romans used flat pieces of lead to draw faint lines on papyrus, but it was not until the late 1400s that the earliest direct ancestor of today's pencil was developed. About one hundred years later graphite, a common mineral occurring as soft, lustrous veins in rocks, was discovered near Borrowdale in northwestern England. The Borrowdale mine supplied Europe with graphite for several hundred years; however, because people could not then differentiate between graphite and lead, they referred to the former as "black lead." Cut into rods or strips, graphite was heavily wrapped in twine to provide strength and a comfortable handle. The finished product, called a lead pencil, was quite popular. In the late sixteenth century, a method for gluing strips of wood around graphite was discovered in Germany, and the modern pencil began to take form. In 1779, scientists determined that the material they had previously thought was lead was actually a form of microcrystalline carbon that they named graphite (from the Greek "graphein" meaning "to write"). Graphite is one of the three natural forms of pure carbon—the others are coal and diamond.

In the late eighteenth century the Borrowdale mine was depleted, and, as graphite was now less plentiful, other materials had to be mixed with it to create pencils. A Frenchman chemist, Nicolas Jacques Conte, discovered that when powdered graphite, powdered clay, and water were mixed, molded, and baked, the finished product wrote as smoothly as pure graphite. Conte also discovered that a harder or softer writing core could be produced by varying the proportion of clay and graphite—the more graphite, the blacker and softer the pencil. In 1839, Lothar von Faber of Germany developed a method of making graphite paste into rods of the same thickness. He later invented a machine to cut and groove the pencil wood. Following the depletion of the once-abundant graphite source at Borrowdale, other graphite mines were gradually established around the world.

A number of these mines were set up in the United States, and the first American pencils were manufactured in 1812, after the War of 1812 ended English imports. William Monroe, a cabinet maker in Concord, Massachusetts, invented a machine that cut and grooved wood slats precisely enough to make pencils. Around that time, American inventor Joseph Dixon developed a method of cutting single cedar cylinders in half, placing the graphite core in one of the halves, and then gluing the two halves back together. In 1861, Eberhard Faber built the United States' first pencil-making factory in New York City.

Today, the hardness of a pencil is designated by numbers or letters. Most manufacturers use the numbers 1 to 4, with 1 being the softest and making the darkest mark. Number 2 pencils (medium soft) are used for normal writing. Pencils are also sometimes graded by letters, from 6B, the softest, to 9H, the hardest. The idea of attaching an eraser to a pencil is traced to Hyman W. Lipman, an American whose 1858 U.S. patent was bought by Joseph Rechendorfer in 1872 for a reported $100,000.

The first step in pencil manufacture involves making the graphite core. One method of doing this is extrusion, in which the graphite mixture is forced through a die opening of the proper size.
The first step in pencil manufacture involves making the graphite core. One method of doing this is extrusion, in which the graphite mixture is forced through a die opening of the proper size.
In addition to the conventional wood pencil, a number of other pencils are widely used. In the early 1880s, the search for a pencil that didn't require sharpening led to the invention of what has variously been termed the automatic, propelling, or repeating pencil. These instruments have a metal or plastic case and use leads similar to those found in wood cased pencils. The lead, lodged in a metal spiral inside the case, is held in place by a rod with a metal stud fastened to it. When the cap is twisted, the rod and stud move downward in the spiral, forcing the lead toward the point. The early twentieth century saw the development of colored pencils in which the graphite core was replaced by a combination of pigments or dyes and a binder. Today, colored pencils are available in more than 70 colors, with 7 different yellows and 12 different blues. However, the cedar-casing lead pencil—manufactured at a pace of 6 billion per year in 40 different countries—continues to outsell all of its competitors, including the ballpoint pen.

Raw Materials

The most important ingredient in a pencil is the graphite, which most people continue to call lead. Conté's method of combining graphite with clay is still used, and wax or other chemicals are sometimes added as well. Virtually all graphite used today is a manufactured mixture of natural graphite and chemicals.

The wood used to manufacture pencils must be able to withstand repeated sharpening and cut easily without splintering. Most pencils are made from cedar (specifically, California cedar), the choice wood for many years. Cedar has a pleasant odor, does not warp or lose its shape, and is readily available. Some pencils have erasers, which are held on with a ferrule, a metal case that is either glued or held on with metal prongs. The erasers themselves consist of pumice and rubber.

The Manufacturing
Process

Now that most commercially used graphite is made in factories rather than mined, manufacturers are able to easily control its density. The graphite is mixed with clay according to the type of pencil being made—the more graphite used, the softer the pencil, and the darker its line. For colored pencils, pigments are added to the clay, and virtually no graphite is used.

Processing the graphite

1 Two methods are used to form the graphite into its finished state. The first is an extrusion method in which the graphite and wax mixture is forced through a mold to create a spaghetti-like string, which is then cut to precise measurements and dried in ovens. In the second method, the graphite and clay mixture is poured into a machine called a billet press. A plug is placed over the top of the press, and a metal ram ascends from the bottom to squash the mixture into a hard, solid cylinder called a "billet." The billet is then removed from the top of the machine and placed into an extrusion press that forces it through a mold, slicing off strips the
To make the wood casings for the pencils, square slats are formed, and then grooves are cut into the slats. Next, graphite sticks are inserted into the grooves on one slat, and then a second slat with empty grooves is glued on top of the graphite-filled slot. Correctly sized pencils are cut out of the sandwich, and the eraser and metal ferrule are attached.
To make the wood casings for the pencils, square slats are formed, and then grooves are cut into the slats. Next, graphite sticks are inserted into the grooves on one slat, and then a second slat with empty grooves is glued on top of the graphite-filled slot. Correctly sized pencils are cut out of the sandwich, and the eraser and metal ferrule are attached.
size of the pencil core. After being cut to size, the cores pass along a conveyor belt and are collected in a trough to await insertion in the pencil wood.

Kết quả (Việt) 1:

Một trong những lâu đời nhất và hầu hết các rộng rãi sử dụng văn bản đồ dùng, bút chì có nguồn gốc trong thời tiền sử khi da mặt xanh xao đá và charred gậy được sử dụng để vẽ trên bề mặt như khác nhau như động vật ẩn và hang động bức tường. Người Hy Lạp và La mã sử dụng miếng bằng phẳng của chì để vẽ các đường mờ nhạt trên giấy cói, nhưng nó đã không cho đến cuối năm 1400 rằng tổ tiên trực tiếp sớm nhất của ngày hôm nay của bút chì đã được phát triển. Khoảng một trăm năm sau đó than chì, một nguồn gốc khoáng sản phổ biến như mềm, bóng tĩnh mạch trong đá, được phát hiện gần Borrowdale ở tây bắc nước Anh. Mỏ Borrowdale cung cấp Europe với than chì trong vài trăm năm; Tuy nhiên, bởi vì những người có thể sau đó phân biệt giữa than chì và dẫn, họ gọi trước đây là "chì đen." Cắt thành thanh hoặc dải, than chì được rất nhiều gói trong quanh co cung cấp sức mạnh và một xử lý thoải mái. Sản phẩm đã hoàn thành, gọi là một bút chì dẫn, là khá phổ biến. Hồi cuối thế kỷ 16, một phương pháp dán dải gỗ xung quanh thành phố than chì được phát hiện ở Đức, và bút chì hiện đại bắt đầu hình thành. Năm 1779, nhà khoa học xác định rằng các tài liệu họ đã nghĩ trước đó đã dẫn đầu là thực sự là một dạng của cacbon microcrystalline mà họ đặt tên than chì (từ Hy Lạp "graphein" có nghĩa là "để viết"). Than chì là một trong ba hình thức tự nhiên của cacbon tinh khiết-những người khác là than đá và kim cương.Hồi cuối thế kỷ 18 Borrowdale mỏ được cạn kiệt, và, như than chì bây giờ ít phong phú, vật liệu đã được trộn lẫn với nó để tạo ra bút chì. Một nhà hóa học người Pháp, Nicolas Jacques Conte, phát hiện ra rằng khi bột than chì, bột đất sét, và nước được pha trộn, đúc, và nướng, các sản phẩm đã hoàn thành đã viết trơn tru tinh khiết than chì. Conte cũng phát hiện ra rằng một lõi bằng văn bản khó khăn hơn hoặc nhẹ nhàng hơn có thể được sản xuất bằng cách thay đổi tỷ lệ của đất sét và than chì — thêm than chì, blacker và nhẹ nhàng hơn những cây bút chì. Năm 1839, Lothar von Faber của Đức phát triển một phương pháp làm than chì dán vào thanh cùng độ dày. Ông sau đó phát minh ra một máy cắt và groove bút chì gỗ. Sau sự suy giảm của nguồn than chì một lần phong phú tại Borrowdale, các mỏ than chì được dần dần thiết lập trên khắp thế giới.Một số các mỏ này được xây dựng tại Hoa Kỳ, và bút chì Mỹ đầu tiên được sản xuất vào năm 1812, sau khi kết thúc chiến tranh năm 1812 Anh nhập khẩu. William Monroe, một hãng sản xuất nội ở Concord, Massachusetts, phát minh ra một máy cắt và rãnh những thanh gỗ chính xác, đủ để làm cho bút chì. Khoảng thời gian đó, nhà phát minh người Mỹ Joseph Dixon đã phát triển một phương pháp cắt đơn cedar bình trong một nửa, đặt than chì lõi trong một trong các nửa, và sau đó dán hai nửa trở lại với nhau. Vào năm 1861, Eberhard Faber chế tạo Hoa Kỳ đầu tiên làm bút chì nhà máy ở thành phố New York.Today, the hardness of a pencil is designated by numbers or letters. Most manufacturers use the numbers 1 to 4, with 1 being the softest and making the darkest mark. Number 2 pencils (medium soft) are used for normal writing. Pencils are also sometimes graded by letters, from 6B, the softest, to 9H, the hardest. The idea of attaching an eraser to a pencil is traced to Hyman W. Lipman, an American whose 1858 U.S. patent was bought by Joseph Rechendorfer in 1872 for a reported $100,000.The first step in pencil manufacture involves making the graphite core. One method of doing this is extrusion, in which the graphite mixture is forced through a die opening of the proper size.The first step in pencil manufacture involves making the graphite core. One method of doing this is extrusion, in which the graphite mixture is forced through a die opening of the proper size.In addition to the conventional wood pencil, a number of other pencils are widely used. In the early 1880s, the search for a pencil that didn't require sharpening led to the invention of what has variously been termed the automatic, propelling, or repeating pencil. These instruments have a metal or plastic case and use leads similar to those found in wood cased pencils. The lead, lodged in a metal spiral inside the case, is held in place by a rod with a metal stud fastened to it. When the cap is twisted, the rod and stud move downward in the spiral, forcing the lead toward the point. The early twentieth century saw the development of colored pencils in which the graphite core was replaced by a combination of pigments or dyes and a binder. Today, colored pencils are available in more than 70 colors, with 7 different yellows and 12 different blues. However, the cedar-casing lead pencil—manufactured at a pace of 6 billion per year in 40 different countries—continues to outsell all of its competitors, including the ballpoint pen.Raw MaterialsThe most important ingredient in a pencil is the graphite, which most people continue to call lead. Conté's method of combining graphite with clay is still used, and wax or other chemicals are sometimes added as well. Virtually all graphite used today is a manufactured mixture of natural graphite and chemicals.The wood used to manufacture pencils must be able to withstand repeated sharpening and cut easily without splintering. Most pencils are made from cedar (specifically, California cedar), the choice wood for many years. Cedar has a pleasant odor, does not warp or lose its shape, and is readily available. Some pencils have erasers, which are held on with a ferrule, a metal case that is either glued or held on with metal prongs. The erasers themselves consist of pumice and rubber.The Manufacturing ProcessNow that most commercially used graphite is made in factories rather than mined, manufacturers are able to easily control its density. The graphite is mixed with clay according to the type of pencil being made—the more graphite used, the softer the pencil, and the darker its line. For colored pencils, pigments are added to the clay, and virtually no graphite is used.Processing the graphite1 Two methods are used to form the graphite into its finished state. The first is an extrusion method in which the graphite and wax mixture is forced through a mold to create a spaghetti-like string, which is then cut to precise measurements and dried in ovens. In the second method, the graphite and clay mixture is poured into a machine called a billet press. A plug is placed over the top of the press, and a metal ram ascends from the bottom to squash the mixture into a hard, solid cylinder called a "billet." The billet is then removed from the top of the machine and placed into an extrusion press that forces it through a mold, slicing off strips theTo make the wood casings for the pencils, square slats are formed, and then grooves are cut into the slats. Next, graphite sticks are inserted into the grooves on one slat, and then a second slat with empty grooves is glued on top of the graphite-filled slot. Correctly sized pencils are cut out of the sandwich, and the eraser and metal ferrule are attached.To make the wood casings for the pencils, square slats are formed, and then grooves are cut into the slats. Next, graphite sticks are inserted into the grooves on one slat, and then a second slat with empty grooves is glued on top of the graphite-filled slot. Correctly sized pencils are cut out of the sandwich, and the eraser and metal ferrule are attached.size of the pencil core. After being cut to size, the cores pass along a conveyor belt and are collected in a trough to await insertion in the pencil wood.